Archive for 2017

2018 Camaro ZL1 1LE Performs on the Track

The new 2018 Camaro ZL1 1LE is the ultimate Camaro model for a day at a closed-course track event. (Fig. 1) The ZL1 1LE Extreme Track Performance Package features a racing-based suspension and aero technologies that make the most of the supercharged 6.2L V8 engine.


Fig. 1




The supercharged 6.2L V8 engine (RPO LT4) produces 650 horsepower and 650 lb.-ft. of torque. (Fig. 2) Power is boosted by the Eaton supercharger intercooler bricks sitting higher in the supercharger housing, improving efficiency, and the unique Tri-Y design of the exhaust manifolds, which improve torque production.


Fig. 2


The V8 engine is paired with the TREMEC 6060 6-speed manual transmission (RPO MH3), which is equipped with Active Rev Match (ARM). Active Rev Match aids in smoother shifting by matching engine speed to the next selected gear. The system is activated or deactivated by pressing either of the paddles marked REV MATCH on the steering wheel. (Fig. 3)


Fig. 3


To keep the demands of the track in check, the cooling system includes a high-performance radiator with dual auxiliary outboard radiators and standard engine oil, transmission and rear differential coolers. (Fig. 4)


Fig. 4




The ZL1 1LE was engineered for the track and has a curb weight that is 60 lbs. (27 kg) lighter than a standard ZL1 coupe, thanks to features such as lighter wheels and dampers, thinner glass in the rear window, and a fixed-back rear seat. Compared to the ZL1, approximately 60–70% of the chassis of the ZL1 1LE is different.


The Brembo® 6-piston fixed cast aluminum front calipers (Fig. 5) and 4-piston fixed cast aluminum rear calipers provide precise braking control while resisting fade. The two-piece front rotors cannot be refinished.


Fig. 5


The Electronic Limited-Slip Differential (eLSD) and the Performance Traction Management system help improve “turn in” response and corner exit speeds while the solid-mounted front and rear cradle mounts provide a faster response from the chassis to the driver, enhancing driver reaction to the road.


The front aero package and rear wing of the ZL1 1LE produces additional downforce for better traction. The front aero package includes a splitter, air deflectors and dive planes on the front fascia. While at the rear is a high-mounted carbon fiber double-sickle wing that produces 300 lbs. (136 kg) of downforce at 150 mph (241 km/h). (Fig. 6)


Fig. 6


Controlling all of that grip are the front and rear Multimatic DSSV® (Dynamic Suspension Spool Valve) dampers. (Fig. 7) The dampers have been calibrated for the car’s weight and tires. They are 23 lbs. (10.5 kg) lighter than the Magnetic Ride Control system on the ZL1.


Fig. 7


The ZL1 1LE features lightweight forged aluminum wheels fitted with Goodyear Eagle F1 Supercar 3R tires — 305/30ZR19 front and 325/30ZR19 rear — that deliver a maximum lateral grip of 1.10g. (Fig. 8) The wider wheels provide an overall footprint that is approximately 10 percent larger than the ZL1, but the wheel and tire package weighs about 3.3 lbs. (1.5 kg) less per corner.


Fig. 8


TIP: High performance summer tires have rubber compounds that lose flexibility and may develop surface cracks in the tread area at temperatures below 20°F (−7°C). Always store high performance summer tires indoors and at temperatures above 20°F (−7°C) when not in use.


Fixed-Back Rear Seat


The rear seat on the ZL1 1LE is a fixed seat in order to reduce weight. The seatback does not fold. If it’s necessary to remove the seatback, use a plastic trim tool between the seatback cushion and the rear window trim panel to release the latch from the seat frame. (Fig. 9)


Fig. 9


Optimizing Performance


The ZL1 1LE features several performance modes, set by the driver, that are designed to allow increased performance in a closed course track environment. Competitive Driving Mode, Performance Traction Management, and Launch Control can be accessed by pressing the Traction Control button twice quickly while in Sport or Track mode. Each mode regulates and optimizes the engine, brakes, and suspension performance while limiting the amount of electronic stability control intervention.


The Chevrolet Performance Data Recorder is available to record video, audio and real-time performance data of a driving session. The data is recorded onto an SD memory card. The SD card reader is below the instrument panel to the left of the steering wheel, just above the hood release lever.


Pre-Delivery Inspection


Some loose-shipped parts of the ZL1 1LE are to be installed by the customer. The following parts are to be installed during the Pre-Delivery Inspection (PDI) process:

  • Front air dam/deflector
  • Rear suspension control arm attachment kit
  • Front tire front air deflector kit (strake)
  • Front tire front air deflector kit (tire strips)


Refer to Bulletin #16-NA-369 for more information.


Hand Washing Only


The ZL1 1LE is not compatible with automatic car washes. It must be hand washed. Do not use any detergent, soap, or cleaners on the matte finish vinyl hood wrap.


For more information on the 2018 Camaro ZL1 1LE, refer to Bulletin #17-NA-251.


– Thanks to Sherman Dixon and Ann Briedis



Preparing a Camaro ZL1 1LE for a Track Event

The 2018 Camaro ZL1 1LE is designed for closed-course track events. (Fig. 10) But before hitting the race course, several preparations should be made in order to get the ZL1 1LE ready to perform in a competitive driving environment. Owners should be aware that these specifications are for the track only and should not be used during normal, everyday driving.


Fig. 10


TIP: High-performance features are intended for use only on closed tracks by experienced and qualified drivers and should not be used on public roads. High-speed driving, aggressive cornering, hard braking, and other high-performance driving actions can be dangerous.


Engine Oil


For track events and competitive driving, change the engine oil to MOBIL 1 15W-50. Do not use 0W-40 engine oil or another viscosity. After four hours of accumulative track use, change the engine oil. After a track event, change the oil back to the engine oil listed in the Owner’s Manual.


When checking the engine oil level, 30 minutes of run time is considered warm to make sure all oil drains back into the pan in order to get an accurate reading.


Brake Fluid


Brake fluid should be changed to DOT 4 fluid for a track event.


Rear Axle Fluid


The rear axle fluid must have accumulated 1,500 miles (2,414 km) of break-in before being used in track driving.


Front Struts


The front struts can be adjusted for track events. The original position is the street position. The front strut top mount can be turned 180 degrees for the track position, which provides additional negative camber.


In the track position, the TRACK CAMBER text will be visible and a second set of top mount holes will align with the strut tower holes. (Fig. 11) Verify and adjust the vehicle alignment per track alignment specifications to optimize vehicle performance for the track event.


Fig. 11


The front struts also have a threaded spring seat that allows adjustment of the preload on the front springs. The vehicle corner weights and front trim heights can be adjusted. The spring seat can be adjusted approximately 0.4 inch (10 mm) up or down from the nominal position. Each complete turn of the spring perch will change the vehicle height approximately 0.06 inch (1.4 mm).


Wheel Alignment


Track wheel alignment specifications are for a vehicle at curb weight conditions, meaning a full tank of fuel and zero ballast. Racing and competitive driving wheel alignment settings may cause excessive tire wear.


Verify and re-adjust the vehicle alignment as needed following the track event.


Rear Stabilizer Bar


The rear stabilizer bar ends have three attachment positions that allow the rear roll stiffness of the vehicle to be adjusted. (Fig. 12) The stabilizer bar stiffness increases approximately 15% using the rearward holes or decreases approximately 10% using the forward holes.


Fig. 12


Tire Pressure


Tire pressure specifications will vary based on driving style, track, temperature, and weather conditions. Limit the vehicle weight to a maximum of the driver and one passenger, with no additional cargo. The Driver Information Center on the instrument cluster can be used to show the current tire temperature status and tire pressures.


Before leaving the track event, reset tire pressures to the recommended inflation pressures on the Tire and Loading Information Label.


Underbody Air Deflector


The underbody air deflector tire dam kit (Fig. 13) provided with the ZL1 1LE reduces the amount of aerodynamic lift on the front axle for better handling on a closed course. The original tire dams must be reinstalled after a track event.


Fig. 13


Water Deflector


When operating the ZL1 1LE on a closed course in hot temperatures, remove the underhood water deflector to increase airflow and improve cooling. The deflector is secured by three bolts. Replace the water deflector immediately after track use to protect the engine compartment from water intrusion.


Safety Belt


The lap shoulder belt has an Automatic Locking Retractor feature, which is useful in performance driving when the driver wants to be held in the seat more tightly to take advantage of the aggressive bolstering of the seat. When the retractor lock is set, the belt can be tightened but not pulled out of the retractor. After locking the belt, adjusting the position of the seat allows for the safety belt to be tighter across the driver’s body.


For more information on the 2018 Camaro ZL1 1LE, refer to Bulletin #17-NA-251.


– Thanks to Sherman Dixon and Ann Briedis


PC Analyzer Tool Easily Checks Techline PC Specs

The GM Dealership Infrastructure Guidelines (DIG) and Dealership Security Guidelines (DSG) were recently updated with additional information to help dealerships in maintaining their overall IT infrastructure. The guidelines published provide a detailed specification of Good (minimum), Better (PCs purchased in the last year or two) and Best (refer to when purchasing new) for personal computers (PC) used in dealership service departments.


On September 1, the Techline Customer Support Center (TCSC) will enforce the standard practice that to receive support for the Techline applications (TIS2Web, GDS2, MDI/MDI 2, SI, etc.), the PC must meet or exceed the minimum required specifications.


The DIG document (U.S.) is available on the GM Dealer Services website.

In Canada, The DIG document is available in GM GlobalConnect under SUPPORT.


PC Analyzer Tool


To easily compare the specifications of PCs currently in use in the service department to the updated requirements, use the Techline PC Analyzer tool that is available from the Utility Tab in TIS2Web. This tool gathers all relevant specifications from the PC and presents them in a concise summary.


Once the PC Analyzer is installed on the PC, click the Techline System Analyzer icon on the desktop to run the application. It will provide a summary of the PC specs, including the Pass/Fail status of the PC system, hardware requirements, anti-virus software and other data. (Fig. 14)


Fig. 14


TCSC can assist with interpreting the results of the PCs in your dealership and what is needed to meet current requirements.


TIP: TCSC will support a technician owned computer if it meets the minimum specification or higher.


If you have any questions related to Dealership Infrastructure Guidelines, contact TCSC at 1-800-828-6860 (English) or 1-800-503-3222 (French).


– Thanks to Lisa Scott

New Special Tools Software Update Download Process

Some GM special service tools, such as the Active Fuel Injector Tester (AFIT) and Pico Scope NVH Tool, require occasional software updates in order to ensure the tool functions properly, offers the latest features, and is applicable to new GM models and systems.


The latest software updates for special service tools are available on the Home page of the special service tools website,


There are different download procedures for GM dealerships and aftermarket users.


Software Download


The software should be accessed through GM GlobalConnect from the Service Workbench selection of “Special Tools & Software Updates.” Accessing the software download through the link on GM GlobalConnect enables dealerships to acquire the download at no-charge since payment will be made through essential tools/parts account billing; if applicable.


Go directly to the Software Downloads page on the special service tools website. (Fig. 15) Search for the parent tool number for the hardware, not the software update number. For example, EL-50334-100A (Multimedia Interface Tester hardware), not the software item number, such as EL-50334-SW2. The software item number will not be found via keyword search.


Fig. 15


To download the update, click the software link listed for the hardware and follow the instructions.


Always refer to the Update Instructions found under the list of Support Documents for more information, if available. (Fig. 16) The Update Instructions cover the steps that should be taken before as well as during the update process to avoid any errors and properly update the tool.


Links to the user guides for the tools also are provided.


Fig. 16


– Thanks to Chuck Berecz

Viewing Emerging Issues Seminars on the new Center of Learning

The new GM Center of Learning (U.S.) — — offers users a number of ways to find and view training opportunities, including the familiar Emerging Issues seminars that are available online each month.


On the Home page, the new Center of Learning shows helpful information on your learning path, current classes and resources as well as the full online catalog and an easy to use search function.


Service technical users also are provided with more detailed information about their learning paths and progress.


Search and Browse


Search for courses by name, course number or keyword using the Search box. Use the filters on the left to narrow your search results. (Fig. 18) Click the tabs above the search results to view related learning paths and resource support materials.


Fig. 18


Select the Browse Catalog tab to browse the courses in the catalog. Click a category to view a list of courses related to that topic.


View Emerging Issues Seminars


After logging into the Center of Learning:

  • Enter “Emerging Issues” in the search box
  • Select the desired Emerging Issues seminar course title. The courses are listed alphabetically.
  • Click the Launch button


TechTube Videos


To view one of the informative TechTube videos, select the GM TechTube link at the bottom of the Home page. The short videos, which run about 10 minutes or less, offer quick and concise reviews of specific repair procedures.


– Thanks to Mike Sculthorpe

Service Know-How

10217.08V – Emerging Issues

August 10, 2017


The latest service topics from Brand Quality and Engineering are reviewed, including a review of proper lift and hoist maintenance (Fig. 19) and some tips on using the Data Bus Diagnostic Tool.


Fig. 19


To view Emerging Issues seminars:

  • Log in to
  • Select Resources > Video on Demand > GM STC > Search Videos; or
  • Select Catalog to search for the course number, and then select View > Take or Continue Course

Top Questions on New Models

Many new GM models have a number of innovative features that enhance the safety and convenience of the vehicle. But some of these features may be unfamiliar to customers and, as a result, they may bring their vehicle into the dealership for service when a system is actually operating as designed. Following are some of the top customer questions regarding new technology, safety and infotainment systems on some 2016-2018 GM models. Ensure customers understand the operation of these features before beginning any diagnosis or repairs.




The programmable power liftgate (Fig 1) can be set to open to a lower height in order to make it easier to reach the liftgate to close, or to prevent contact with a low ceiling, garage door, or roof-mounted cargo.


Fig. 1


Programming the Liftgate Height


The power liftgate knob is usually located on the driver’s door (Fig. 2) or the overhead console. It has three modes:


MAX: Opens the liftgate to the maximum height.

3/4: Opens to a reduced height that can be set from 3/4 open to fully open.

Off: Opens manually only.


Fig. 2


To program the liftgate’s opening height:

  1. Turn the power liftgate knob to the MAX or 3/4 position.
  2. Open the liftgate and adjust it manually to the desired height.
  3. Save the height setting by pressing and holding the power liftgate close button next to the latch on the liftgate for three seconds. The turn signals will flash and a beep will sound when the setting is saved.


With the liftgate programmed, it will open to the set height if the power liftgate knob is in the 3/4 mode.


Hands-Free Operation


If the liftgate is equipped with hands-free operation, the liftgate can be opened or closed by using a kicking motion under the rear bumper. The location of the rear bumper sensor varies based on the vehicle. Do not swing your foot side-to-side. The key fob must be within 3 feet (1 meter) of the liftgate.


Some 2018 models also feature a vehicle logo that is projected onto the ground under the rear bumper sensor that indicates where the kicking motion should take place. (Fig. 3) The logo is projected when the key fob is detected within 6 feet (2 meters) of the liftgate. Based on operating conditions, the logo will be projected for one minute.


Fig. 3




The customer may be expecting a warning chime when the Lane Keep Assist with Lane Departure Warning system is active. However, there is not a warning chime if the system determines the driver is actively steering.


The Lane Keep Assist system can be turned on/off using the button located on the steering wheel, center console (Fig. 4) or instrument panel. Make sure the customer has not inadvertently turned the system off.


Fig. 4


Lane Keep Assist Function


Lane Keep Assist will provide steering input to gently turn the steering wheel to help center the vehicle in the traffic lane if the vehicle approaches a detected lane marking without using a turn signal in that direction. (Fig. 5) The Lane Keep Assist icon is green on the instrument cluster if the system is available to assist and turns amber when the system is providing steering input. As the driver actively steers the vehicle, the steering input and amber indicator may not be noticed.


Fig. 5


Lane Departure Warning Function


If the driver does not actively steer the vehicle and crosses the lane marking without using a turn signal in that direction, the Lane Departure Warning will then provide a warning by flashing the amber icon and pulse the Safety Alert Seat or sound a chime/beeps. Audible beeps or seat pulsing alerts may be selected in the Settings menu.




Many GM models now feature Auto Engine Stop/Start technology to help conserve fuel and provide better fuel economy. The Auto Engine Stop//Start system shuts down the engine when the vehicle comes to a complete stop, referred to as an Auto Stop, if operating conditions are met. When in Auto Stop mode, the tachometer will read AUTO STOP. The audio system, climate controls and other accessories will continue to operate. By releasing the brake pedal or applying the accelerator pedal, the engine will restart.


When the engine is turned off using the ignition pushbutton, the tachometer will read OFF. (Fig. 6)


Fig. 6


The Auto Engine Stop/Start system can be turned off using a control button on some GM models. (Fig. 7)


Fig. 7


Operating Conditions


The engine may not turn off at a stop or may restart if any of the following conditions apply:

  • A minimum vehicle speed is not reached.
  • The engine or transmission is not at the required operating temperature.
  • The outside temperature is not in the required operating range.
  • The shift lever is in any gear other than Drive (D).
  • The battery charge is low.
  • The climate control system requires the engine to run based on the climate control or defog setting.
  • The Auto Stop time is greater than two minutes.




The new touchscreen infotainment systems (Fig. 8) offer a variety of entertainment, communication and vehicle system options. Simple gestures can be used on many of the touchscreen systems just as on a tablet, such as tap, drag, swipe and pinch/spread. Touching an application icon or screen button accesses that feature, menu or setting.


Fig. 8


Customers can use a Bluetooth or USB connection to link to a compatible smartphone, cell phone, USB flash drive, or portable audio player.


Detailed information and Frequently Asked Questions on how to use a variety of system functions are covered at the following websites:

Buick IntelliLink Radio Guide

Chevrolet Mylink Vehicle Technology

GMC IntelliLink Infotainment System

In Canada, visit or




In addition, helpful videos and more information about the operation of many features on new GM models can be found at the following GM owner websites: (Canada)


Choose your vehicle using the drop-down menus and select Learn About Your Vehicle.


– Thanks to Tyler Greenhill



Loss of Communication while Viewing HMI Data List

While performing service procedures involving the Human Machine Interface (HMI) module, viewing the HMI data parameters using GDS2 may cause a temporary loss of communication with the scan tool. This condition may be found on 2016 ELR; 2016-2017 ATS, CTS, XTS; 2016-2018 Encore, Envision, LaCrosse, Regal, CT6, Escalade, Camaro, Colorado, Corvette, Impala, Malibu, Silverado, Suburban, Tahoe, Canyon, Sierra; 2017-2018 XT5, Acadia; and 2018 Equinox models equipped with RPOs IO5, IO6, RAO, or UY4.


On some vehicles, viewing the HMI data parameters (Fig. 9) for as little as 5–60 seconds using GDS2 may induce a temporary loss of HMI communication with the scan tool. This condition may occur on a vehicle that has no concerns as well as a vehicle that has an unrelated customer concern. If a loss of HMI communication occurs with no other conditions, do not replace the HMI module.


Fig. 9


Power Cycle the HMI Module


Communication can sometimes be re-established with GDS2 by simply clicking OK when the “No HMI Communication” screen is displayed. In some other cases, it may be necessary to remove the HMI fuse for a few seconds and then reinstall the fuse to re-establish HMI communication. If there are not any related DTCs set or other concerns with the HMI, the HMI data parameters should be temporarily viewable again (for only one minute or less) after reinstalling the HMI fuse, before the cycle starts again.


If the loss of HMI communication with GDS2 occurs and TIS2Web is used to program the HMI module without first restoring communication with the HMI module by power cycling it (cycling the fuse for a few seconds or cancelling Retained Accessory Power), an E-4491 SPS error code may appear. However, the HMI module should not be damaged and it should be possible to continue with programming by power cycling the HMI module and then immediately entering TIS2Web.


The loss of HMI communication while viewing the HMI data parameters using GDS2 is due to a software issue that causes the HMI to the prematurely leave the diagnostic/service mode and return to normal operation.


Do not replace the HMI module or any other parts if this condition is found. GM Engineering is currently evaluating this condition. In the meantime, power cycling the HMI fuse should restore communication unless another issue exists that requires further diagnosis and repair.


– Thanks to Ryan Dorland

Hard Shifting into 1st Gear or Reverse

Hard shifting conditions when shifting into 1st gear or Reverse may be found on some 2014-2018 Silverado, Sierra and Corvette models equipped the 4.3L V6 engine, 5.3L V8 engine or 6.2L V8 engine (RPOs LV3, L83, L86, LT4) and 2015-2018 CTS-V, Escalade, Tahoe, Suburban, Yukon; and 2016-2018 Camaro models equipped with the 5.3L V8 or 6.2L V8 engine (RPOs L83, L86, LT4).


On Silverado, Sierra, CTS-V, Escalade, Tahoe, Suburban, Yukon, and Camaro models, when shifting the automatic transmission into Drive or Reverse, a clunk sound may be heard.


On Corvette models only, it may be difficult to shift into 1st gear or Reverse with a manual transmission or there may be a vibration on takeoff or a clunk noise when shifting into Drive or Reverse with an automatic transmission.


Crankshaft End Play


The hard shifting conditions may require replacement of the crankshaft or thrust bearing. Before replacing any components, check for excessive crankshaft end play. Crankshaft end play clearance should be within a specification of 0.0015–0.0086 in. (0.040–0.220 mm).


Crankshaft Wear


If end play is found to be out of specification, remove the engine and check for possible crankshaft thrust bearing or crankshaft wear. The crankshaft and bearings should not show signs of excessive wear. (Fig. 10) Inspect the thrust bearing for wear on one side and the crankshaft on the mating surface.


Fig. 10


If wear is evident — the three vertical channels may be worn off — replace the connecting rods, main bearings, thrust bearing and crankshaft.


TIP: On engines with a dry sump oil system, the oil tank and lines, and the oil cooler (if equipped) (Fig. 11), should be replaced when repairing the engine.


Fig. 11


– Thanks to Richard Renshaw


Diagnostic Tips for Harsh Shifting Transmission Conditions

Harsh shifting conditions and delayed garage shift engagements may be noticed on some 2017 Colorado, Canyon, Express, Savana; 2016-2017 ATS, CT6, CTS, Camaro; 2015-2017 Escalade, Silverado, Sierra, Yukon Denali, and Corvette models equipped with the 8L45 or 8L90 automatic transmission (RPOs M5N, M5T, M5U, M5X). (Fig. 12) The harsh shift conditions may be caused by one or more clutch fill times not completely learned in the Transmission Control Module (TCM).


Fig. 12


DTCs and Updated Calibrations


As a starting point for diagnosing all 8L45/8L90 transmission shift conditions, check for DTCs in all modules and address the causes for setting the DTCs. Also check for any available ECM/TCM calibration updates.


Refer to the following bulletins for additional information:

  • 16-NA-411 – 2015-2016 models equipped with the 6.2L engine (RPO L86) engine and the 8L90 transmission
  • 16-NA-412 – 2015-2016 models equipped with the 5.3L engine (RPO L83) engine and the 8L90 transmission
  • 16-NA-404 – 2017 models


Test Drive with GDS2


A test drive of the vehicle should be completed in order to attempt to duplicate the concern. Use GDS2 to capture a session log of the event and bookmark when the shift concern is identified. Review the GDS2 session log to identify which shift(s) are occurring at each bookmark.


Refer to the following bulletins for additional information:

  • 14-07-30-001: Information on Transmission Adaptive Functions and Correcting Low Mileage Harsh Shifts, Slips, or Flares – 2015 Corvette
  • 16-NA-411, 16-NA-412 and 16-NA-019: Updating ECM/TCM Calibrations – 2015 models other than Corvette
  • 16-NA-019: Information on Transmission Adaptive Functions and Correcting Low Mileage Harsh Shifts, Slips, or Flares – 2016-2017 models


These bulletins are based on the following criteria:

  • 2015 models with 7,500 miles (12,000 km) or less since the vehicle in-service date, TCM calibration update or the Service Fast Learn (SFL) procedure being performed
  • 2016 models with 5,000 miles (8,000 km) or less since the vehicle in-service date, TCM calibration update or the SFL procedure being performed
  • 2017 models with 2,500 miles (4,000 km) or less since the vehicle in-service date, TCM calibration update or the SFL procedure being performed


Transmission, valve body or TCM replacement requires a Service Fast Learn procedure using a scan tool to be performed in order for the TCM to learn individual clutch apply pressures. If the TCM calibration has been updated, a Service Fast Learn procedure is required on vehicles with any mileage accumulation.


Clutch Drive Learn Procedure


Based on the bookmarks placed in the GDS2 session, complete the Clutch Drive Learn procedure for the suspect clutch. The Clutch Drive Learn procedure should only be performed on smooth, level roads and may take 45 minutes or more.


Completion of the Service Fast Learn procedure will reset all shift adapts and may require the entire transmission Clutch Drive Learn procedure for each clutch to be completed.


After completing the procedure, the vehicle should be allowed to cool down for eight or more hours and then test driven again to ensure the cold shift quality is acceptable.


Refer to the following bulletins for more information:

  • 16-NA-361: Transmission Harsh 1-2 Shift Upon First Start Up/Shift of the Day Under Light Throttle
  • 16-NA-213: Diagnostic Tips for Harsh Shifts after Mileage Accumulation without Previous Transmission Repairs and/or Calibration Updates – Transmissions built between July 1, 2015 and September 14, 2015.


Garage Shifts


Refer to the following bulletins for more information:

  • 16-NA-014: Delayed Engagement After Sitting With Engine Off. Torque Converter Fluid Drain Back – 2015-2016 models
  • 16-NA-364: Delayed Engagement After Sitting With Engine Off, Clutch Slow to Fill – 2015-2017 models


– Thanks to Terry Neuendorf


Preventing an Inadvertent Remote Start during Service

With the growing popularity and availability of GM models equipped with remote start and the OnStar mobile app, it’s a good time for a reminder that there is potential for personal injury to technicians or damage to a vehicle during vehicle service if the remote start function isn’t disabled.


2009-2018 GM models may be equipped with remote start or the OnStar mobile app, which enables owners to send a remote start command to the vehicle using a smartphone. In a situation where a technician is working on a repair from underneath the vehicle — where the vehicle would be on a hoist and the hood closed — the vehicle could be inadvertently started using the remote start function or the mobile app remote command.


The inadvertent remote start may occur in a couple of common instances. The vehicle owner may start the vehicle using the OnStar mobile app (Fig. 13) out of habit, such as during lunchtime or at the end of the day, forgetting that the vehicle is being repaired. Another case could be if dealership personnel accidentally start the wrong vehicle using an incorrect key fob. The common appearance of key fobs could create a situation where the wrong fob is used, leading to an accidental engine start-up.


Fig. 13


Always Open the Hood


When performing repairs in the engine compartment or under the vehicle, always fully open the hood (Fig. 14), or open the hood to its secondary latch, so that the remote start function will be disabled. Failure to fully open the hood, or open it to its secondary latch, during service could result in personal injury or damage to the vehicle if an inadvertent remote start occurs.


Fig. 14


Always pay attention to the Dangers, Warnings and Cautions in the appropriate Service Information when performing repairs. The remote start warning also is included under Hoist Procedures as well as the general warning statement presented when logging into the Service Information.


– Thanks to Matt Bunting

The All-New 2018 Chevrolet Traverse

The all-new 2018 Traverse (Fig. 1) features a bold design, seating for up to eight passengers, and new technologies in six trim levels: LS, LT, RS, Premier, Redline, and High Country.


Fig. 1


A new 3.6L V6 engine (RPO LFY) is available on front-wheel drive (FWD) and all-wheel drive (AWD) models. The new RS model, which is FWD only, features a 2.0L turbocharged 4-cylinder engine (RPO LTG). All models have standard Intelligent Stop/Start technology to help conserve fuel. Both engines are paired with the 9T65 9-speed automatic transmission (RPO M3V) that offers smoother shifting and improved fuel economy.


The High Country model (Fig. 2) also is equipped with the Twin Clutch AWD system (RPO G99), which independently controls torque to each rear wheel, providing superior control with less brake intervention. The advanced AWD system is automatic and always engaged when AWD mode is selected using the Driver Mode Control on the center console. The LS, LT, Premier and Redline AWD models are equipped with single-clutch AWD.


Fig. 2


The design of the new Traverse includes an overall weight reduction of approximately 362 lbs. (164 kg) from the previous model when equipped with the 2.0L engine. The weight reduction comes mostly from the use of thinner-gauge high-strength steels.


3.6L V6 Engine


The 3.6L V6 engine (Fig. 3) features variable valve timing (VVT) and direct injection (DI) and generates an estimated 305 horsepower and 260 lb.-ft. of torque. The DI system places the high pressure injectors in the cylinder heads. The engine has E85-compatible valves and seats with special materials and coatings that require slightly different service procedures from gasoline valves. Gasoline with an octane rating of 87 or higher is recommended.


Fig. 3


The cylinder block is constructed of aluminum alloy by precision sand-casting with cast-in-place iron cylinder liners. The cylinder heads are cast aluminum with powdered metal valve seat inserts and valve guides. The cylinder heads also feature integrated exhaust manifolds. Which incorporate the exhaust manifolds into the head casting. The engine uses ACDelco dexos1 SAE 5W-30 viscosity grade engine oil.


2.0L 4-Cylinder Engine


The 2.0L turbocharged 4-cylinder DOHC engine (Fig. 4) is based on a generation of large displacement four cylinder engines designed for greater efficiency. It produces 255 horsepower and 295 lb.-ft. of torque.


Fig. 4


The engine features a sand-cast aluminum cylinder block and aluminum cylinder heads. The direct injector mounting locations are below the ports. The two-stage variable displacement oil pump helps maximize fuel efficiency by matching oil supply to engine load. The engine uses ACDelco dexos1 SAE 5W-30 viscosity grade engine oil.


The turbocharger generates up to 20 pounds (138 kPa) of boost and its twin- scroll design helps optimize the usable power from the engine. Electronically controlled turbocharger supporting components, including the wastegate and bypass valve, help optimize performance and efficiency. The turbocharger intake system is supported by an air-to-air charge air cooler system.


Premium gasoline with an octane rating of 93 is recommended for best engine performance and fuel economy.


Intelligent Stop/Start


The Intelligent Stop/Start system, which turns off the engine when at a stop in certain conditions to reduce fuel consumption and emissions, is standard on both engines. It’s similar to the Stop/Start systems found on other GM models, but it offers quieter engine stops/starts with fewer vibrations and can recognize certain driving maneuvers, such as backing into a garage or parking lot situations. An advanced algorithm determines when driving conditions are optimal for engine shut-off. The engine automatically restarts after approximately two minutes if the driver hasn’t removed their foot from the brake pedal.


The system features a tandem-solenoid starter, a unique DC-DC module that maintains voltage during a stop/start event, an electronically controlled accumulator that retains the transmission fluid pressure to keep the clutches engaged for immediate takeoff when the brake pedal is released, and an engine mount system that dampens the vibrations associated with a restart.


9T65 Automatic Transmission


The 9T65 automatic transmission is transverse mounted and features a 4-element torque converter, a compound planetary gear set, friction and mechanical clutch assemblies, and a hydraulic pressurization and control system.


The planetary gear sets provide the 9 forward gear ratios and reverse. The Transmission Control Module (TCM) receives and monitors various electronic sensor inputs to shift the transmission at the optimum time. Use DEXRON-VI transmission fluid in the 9T65 transmission.


Twin Clutch AWD


The Twin Clutch AWD system delivers greater handling and stability by preemptively and electronically splitting the torque as needed between the rear wheels using twin clutches to provide added traction, stability and control versus a 50/50 split in a single clutch system.


The Twin Clutch system with active torque bias has increased capability to add stability across all driving conditions, including when one side of the vehicle is on a slippery surface and the other side has more traction. In addition, a fuel economy benefit is realized by not pushing torque when it is not needed.


Traction Select System


The Traction Select system adjusts the vehicle’s throttle response, shift mapping and stability control to maximize performance in varying road conditions based on the mode selected. The different driving modes are selected using the Driver Mode Control on the center console. (Fig. 5) If equipped with FWD, the Driver Mode Control may have the following mode selections: FWD, Snow, and Tow/Haul. If equipped with AWD, the Driver Mode Control may have Two-Wheel Drive (2WD), AWD, Off-Road, and Tow/Haul.


Fig. 5


On AWD models, the driver can switch between FWD and AWD operation when conditions dictate without having to stop the vehicle. The AWD Mode will stay selected until the mode is changed. If the customer switches to FWD, the system efficiently disconnects virtually all of the AWD components from the drivetrain so the gears and prop shafts stop spinning, saving fuel and reducing emissions.


Braking Systems


All models have four-wheel disc brakes with Duralife brake rotors and an electric parking brake. The Electronic Brake Control Module (EBCM) and the brake pressure modulator are serviced separately.


Depending on how the vehicle is equipped, performance enhancement systems may include Antilock Brakes, Dynamic Rear Proportioning, Hill Hold Start Assist, Intelligent Brake Assist, Traction Control and Electronic Stability Control, Trailer Brake Control, and Trailer Sway Control.


Infotainment Systems


The Traverse is equipped with Chevrolet MyLink, which offers Apple CarPlay and Android Auto compatibility, and either a standard 7-inch (179 mm) diagonal touch screen (RPO IOA) or an available 8-inch (203 mm) diagonal touch screen (RPO IO5) with optional embedded navigation (RPO IO6).


The 8-inch touch screen features gesture recognition control that lets drivers use their fingertips to navigate around screens by clicking, dragging and swiping, similar to the gestures used on a tablet. The 8-inch touch screen also raises to reveal a hidden storage compartment behind the screen. (Fig. 6)


Fig. 6


Automatic Climate Control


The Traverse features a standard tri-zone automatic climate control system with two zones in the front row and one zone in the second row. Controls are on the instrument panel and on the rear of the front row console. The second-row settings can be controlled using the infotainment touch screen. The system uses R-1234yf refrigerant. A new brushless blower motor helps eliminate the humming sounds an HVAC system can create, providing a quieter cabin.


Hands-Free Power Liftgate


The programmable power liftgate has an available hands-free functionality that enables the liftgate to be opened or closed by using a kicking motion under the rear bumper. An optional projected Chevrolet bowtie indicates the kick location, which is under the left side of the bumper. (Fig. 7) Certain conditions must be met in order for the projection to appear.


Fig. 7


TAC Action Center (U.S.)


The GM Technical Assistance Center (TAC) has established an Action Center for the 2018 Traverse. TAC Action Centers are designed to gather early feedback and provide support for the introduction of new GM models. Dealership service departments are asked to report all vehicle issues that require immediate attention, not just concerns that require technical assistance. The goal is to develop a quick resolution to any product concerns, such as fit and finish, performance, and operation.


Action Centers have a direct connection to GM Engineering, Brand Quality and the assembly plant, which offer combined resources to immediately address product concerns seen in the dealership. Product concerns and repairs reported by technicians to the Technical Assistance Center is critical to helping ensure a successful model launch.


To contact the Traverse Action Center, call TAC and follow the prompts to:

  1. Select Speak with a Consultant for Vehicle Diagnostics
  2. Enter BAC Code
  3. Select Action Centers
  4. Select Traverse Action Center


In Canada, dealerships should follow the usual process when contacting TAC.


For more information on the new 2018 Traverse, refer to Bulletin #17-NA-176.


– Thanks to Sherman Dixon and Steve Bruder





New GM Dealer Infrastructure Guidelines Adopt Good, Better, Best Format

GM has released new Dealership Infrastructure Guidelines (DIG) and introduced a new document, Dealership Security Guidelines (DSG). The Dealership Infrastructure Guidelines are updated periodically to stay current with technology that should be in place at the dealership, including Personal Computer (PC) and network hardware, software, wireless networking, digital signage, Information Technology (IT) continuity management, internet optimization and data network security. These guidelines provide the specifications necessary to run GM applications efficiently and securely in the dealership.


GM created the Dealership Security Guidelines to assist dealerships with implementing security processes for effective data security controls.


The new guidelines (Fig. 8) are available on the GM Dealer Services website. On the website, select each link to download and save the DIG and DSG. In Canada, the IT guidelines are located within GlobalConnect under SUPPORT.


Fig. 8


New Format


The Dealership Infrastructure Guidelines feature a new format that provides Good, Better, and Best specifications (Fig. 9) for running GM Techline service applications (TIS2Web, GDS 2, MDI, MDI 2, Tech2Win, and Service Information).


Good – the minimum acceptable systems capability/components for conducting business with GM.


Better – the systems capability/components that will deliver better performance and security.


Best – the systems capability/components that will provide the best performance and security while maximizing the lifecycle of the investment.


Fig. 9


GM estimates the average life cycle of a desktop, laptop or tablet PC to be approximately three years. When purchasing a new PC or laptop, it’s recommended to follow the specifications from the Best category. The software used in the service department to diagnose and repair GM vehicles requires the most computing power to perform efficiently as well as to meet future demands.


Most computer manufacturer’s offer consumer-grade hardware intended for home/personal use and enterprise-grade hardware intended for businesses. While consumer-grade hardware may seem attractive based on price, the total cost of ownership often ends up being greater due to the limited functionality, higher failure rates, and more complex support necessary.


TIP: Where the device will be used should be considered when purchasing a laptop or tablet PC. If the device will be used in the service department, a rugged case design is recommended.


Dealership Support


Starting September 1, 2017, the Techline Customer Support Center (TCSC) will ask each caller to provide the specification of the Techline PC regardless of call type. If the PC is below the minimum specification, the caller will not receive support.


For service or parts department PC questions related to the Dealership Infrastructure Guidelines, contact the TCSC at 1-800-828-6860. For questions related to the Dealership Security Guidelines, contact GMDIT at 1-888-337-1010. In Canada, for questions related to Service Department PCs or Service Technician apps, contact TCSC at 1-800-828-6860 (English) or 1-800-503-3222 (French). For questions related to the GM Infrastructure Guidelines, contact Canadian Dealer Systems Support at 1-800-265-0573.


– Thanks to Lisa Scott


DC Fast Charger for EV Charging

The amount of time it takes to fully charge the 2017 Bolt EV with a depleted high voltage battery depends on the type of charger being used. With the 120-volt portable charge cord at the default 8-amp setting, it takes over 50 hours to fully charge the vehicle. Using a 240-volt charging station set at a 16-amp level, the charging time is reduced to approximately 19 hours. But using a DC Fast Charging station on vehicles with the available Fast Charge port, the charging time to achieve 90 EV miles (145 km) is reduced to only about 30 minutes. This fast charge rate makes it more convenient for dealerships to keep Bolt EV models in inventory charged or to quickly recharge a vehicle visiting the dealership. Individual charging times and rates will vary depending on outside temperature and remaining charge.


The EL-52240C DC Fast Charger (Fig. 10) was recently shipped to all Bolt EV-authorized Chevrolet dealerships. The DC Fast Charger can be used on Bolt EV and Spark EV models equipped with the available DC Combo charging port connector.


Fig. 10


EL-52240C DC Fast Charger


The 25kW DC Fast Charger is weatherproof and lightweight, so it can be installed indoors or outside on a wall or on a pedestal. It features an easy-to-use interface with two simple function buttons.


The DC Fast Charger requires a single phase connection that can support 165A continuous current. Installation should only be performed by a licensed electrician.


Two keys are provided that are used to turn off the DC Fast Charger when not in use or after hours. Turn the key to turn the power on or off. Two optional access cards also can be used to restrict access to authorized users only.


A Configuration Tool is available at that offers advanced configuration options, such as maximum charging time and power limits.


Accessories that are available with the DC Fast Charger include a wall-mounted cable dock (EL-52240-DOCK) that holds the cable and vehicle coupler and a pedestal mount (EL-52240-GNT) that allows the DC Fast Charger to be installed in an open area. (Fig. 11)


Fig. 11


DC Charging


The available SAE J1772 DC Combo charging port (Fig. 12) feeds power directly to the vehicle’s battery to significantly reduce the charging time, which will vary based on outside temperature. The combo charging port is an optional feature (standard in Canada). If the vehicle is not equipped with this charging port, it is not compatible with DC charging.


Fig. 12


The DC Fast Charger will quickly charge a depleted battery to approximately 90% state of charge in about two hours. It will continue to charge the vehicle to 100%, but at a slower rate.


To charge the Bolt EV, unlatch the DC charging dust cover on the charge port in order to plug in the charge cord. Follow the steps on the DC Fast Charger to start charging. The DC plug will be locked and cannot be disconnected while charging is active. The Charge Status indictor on top of the vehicle’s instrument panel, near the windshield, will illuminate green and the horn will chirp when properly connected.


To stop charging at any time, use the controls on the DC Fast Charger or touch the Stop button on the vehicle’s Battery information screen.


– Thanks to Chuck Berecz




Turning On the Wi-Fi Hotspot

The Wi-Fi hotspot may not appear to be working on some 2018 Sonic, Trax, and Terrain models equipped with infotainment system RPO IOR (3.X Low HMI, Midlevel Connectivity 3.X).


On infotainment system RPO IOR, there are two settings that must be turned on in order for the Wi-Fi hotspot to be enabled as well as to share data with a connected device. Owners may have turned on the Wi-Fi hotspot without activating the sharing data function.


From the infotainment system Home screen, go to Settings > System > Wi-Fi Hotspot. (Fig. 13)


Fig. 13


Select Wi-Fi Services under the Wi-Fi Hotspot menu to turn on the Wi-Fi hotspot. The On indicator will be green when the setting is turned on. (Fig. 14)


Fig. 14


Scroll down in the Wi-Fi- Hotspot menu to select Share Hotspot Data to activate the sharing data function. The On indicator will be green when the setting is turned on. (Fig. 15)


Fig. 15


Check that both of these settings are turned on if there is a concern regarding the functionality of the Wi-Fi hotspot before pursuing additional diagnostics or repairs.


– Thanks to Ed Flanagan

SPS Updated to Prohibit or Warn about Programming with Same Calibration

In an effort to decrease the number of unneeded programming events, reduce the risk of programming-induced faults, and support timely vehicle repairs, the Service Programming System (SPS) has been updated recently to prohibit or warn users against programming a control module with the same calibration that is already present in the control module. This SPS change prohibiting reprogramming using the same calibration applies to all 2017-2018 Buick, Cadillac, Chevrolet and GMC models.


Prohibited Programming


On 2017 and newer models, reprogramming a control module with the same calibration that is already in the control module will be prohibited by SPS. Users who attempt to reprogram a control module with its current calibration will receive the warning message “You are attempting to reprogram with the same calibration. This is not allowed for the selected ECU.” (Fig. 1) Selecting OK will end the programming event.


Fig. 1


Warning on Same Calibration


On 2016 and older models, programming a control module with its current calibration is not prohibited, but is not a recommended service procedure. Users who attempt to reprogram a control module with the same calibration will receive a warning message. (Fig. 2)


Fig. 2


Selecting Cancel will stop the programming event. If OK is selected, a second warning will appear. (Fig. 3)


Reprogramming with the same calibration is not recommended, but selecting OK again on the second warning message will allow the programming event to proceed.


Fig. 3


These warning messages do not indicate an issue with the control module in question and that it should be replaced, only that the control module already has the calibration being programmed. Follow the diagnostic procedure in the appropriate Service Information to determine the root cause.


– Thanks to Andrew McKittrick


SPID Label Content Now Included with Certification Label

The Service Parts Identification (SPID) label, often located in the trunk or glovebox of a vehicle, lists a vehicle’s VIN, RPO codes and other information that identify the content of the vehicle. Beginning with the 2018 model year, much of this information will be available through a QR code on the Certification label (Fig. 1) on all Buick, Cadillac, Chevrolet and GMC models. The change will be phased in over the next several months.


Fig. 1


The two-dimensional QR code is a simple barcode that offers the former SPID information in a digital format. The Certification label on all GM models is located on the driver-side B pillar, with the exception of the Corvette where it’s on the driver’s door.


QR Code


Software to read the QR code is commonly available for any Android, iPhone or Windows smartphone. Many basic applications can be downloaded for free. Tested QR code readers that are easy to use include NeoReader by NM LLC, i-nigma by 3GVision, QR Scanner by Honestly App, QR Droid by DroidLa and Bar-Code by PW2. GM does not recommended any particular software.


Once the QR code is scanned, the vehicle information will appear in the following order: VIN, Model Year, Model, Build Month, Year, Engineering Book, Vehicle Order Number, 3 Digit RPO Codes sorted alphanumerically, and the Paint Code (same code appears in the lower left of the QR code).


For example, here’s the information as shown from a scanned QR code:


1GNKVGKD1HJ263691,2017,CV14526,03,16,17,TSNWHZ, AG5 AH5 AR9 AXP AYQ C67 DLT DS3 EF7 FE2 GZW IPC I17 JL9 LLT MAH M7X NP5 NT7 QD6 QLW TB4 UI2 UQF U2K V8D WMH X88 1LT 17U 5PK 6AB 7AB 8UM 83C 83I 9UM,636R, , , ,


The RPO codes are bolded above, but not in the actual information. The codes are separated by a space. Up to 48 RPO codes may be displayed. RPO descriptions can be found in the appropriate Service Information under General Information.


If the vehicle information needs to be retained for service records or shared with others, most scanner software also has a selection to email the data. (Fig. 2)


Fig. 2


– Thanks to Lisa Scott

Programming a Replacement OnStar Module

If the OnStar module is replaced in a 2009-2018 Buick, Cadillac, Chevrolet or GMC model, several conditions may occur if the module is not properly programmed or activated. These conditions may include a red LED illuminating, no Wi-Fi operation (Mobile Internet Connectivity RPO VV4 only) and limited OnStar module functionality occurring shortly after replacing the module.


TIP: Depending on model and model year, the OnStar module also may be identified in the Service Information, TIS2Web, the parts catalog, or a scan tool as the Vehicle Communication Interface Module (VCIM), Communication Interface Module, Telematics Communication Interface Control Module, or OnStar Vehicle Interface Unit (VIU).


Review every step of the Communication Interface Module Programming and Setup procedure in the appropriate Service Information to ensure all steps were completed.


If there is any question about the proper operation of the OnStar module, press the blue OnStar button to call OnStar. If OnStar confirms incomplete programming or activation, perform the Communication Interface Module Programming and Setup procedure again from the beginning without skipping any steps and then re-evaluate the concern.


Programming and Setup Tips


While all steps in the programming and setup procedure are important, the following items must be followed to ensure proper operation of the replacement OnStar module.


  • All replacement OnStar modules require TIS2Web programming. Complete every step of the Communication Interface Module Programming and Setup procedure.


  • U.S. dealerships should not select the TIS2Web selection that refers to Canadian upgrade bulletin #15-08-44-001 on a vehicle that has not had the Canadian upgrade performed. Programming and Service Activation should be selected. (Fig. 3)


Fig. 3


  • From the SPS Supported Controllers screen, select Programming and Service Activation. Do not select an incorrect option that does not apply to the vehicle (e.g. Export, Only for RPO XXX, etc.).


  • Select the Reprogram ECU option at the start of TIS2Web programming. Do not select the Replace and Reprogram ECU option. (Fig. 4)


Fig. 4


  • Do not select the OnStar Wi-Fi Enable (Gen 10 only) Programming procedure until the TIS2Web Programming and Service Activation procedure has been completed (RPO VV4 only). (Fig. 5)


Fig. 5


  • Press the blue OnStar button (Fig. 6) to call OnStar and confirm proper operation once the TIS2Web Programming and Service Activation procedure has been completed if required in the Communication Interface Module Programming and Setup procedure. To ensure that OnStar receives everything from TIS2Web needed to confirm proper operation, wait at least five minutes with the vehicle in an area with a clear view of the sky before pressing the blue OnStar button.


Fig. 6


– Thanks to Jamie Parkhurst



Mark of Excellence Q3 Test on Center of Learning

The Q3 (3rd quarter) Mark of Excellence Product Knowledge Test (U.S.) for technicians is available now on the Center of Learning website at Each of the four quarterly tests measure technicians’ knowledge of GM products. Questions are based on GM training, Service Information, Service bulletins and other resources.


Technicians who complete the Q3 test by July 28, 2017, with a score of 80% or better, will earn 50 bonus points towards their year-end recognition award. The Q1 and Q2 tests also can still be completed.


TIP: Tests are not part of a technician’s training path, but are listed separately under Mark of Excellence Product Knowledge Tests. The Q3 test can be found on the Center of Learning website under Course Catalog > Course Number Search: 30017.03P.


Technicians earn a quarterly drawing entry for successfully completing (80% or better) the Mark of Excellence Product Knowledge Tests. 10 technicians per zone will be selected by random drawing to receive 250 earnPOWER points.


In addition, technicians who successfully complete all four Product Knowledge Tests will receive an apparel item at year end.


Mark of Excellence Awards


The 2017 Mark of Excellence Program recognizes the top service technicians at GM dealerships for their achievements in technical training, product knowledge, customer satisfaction and outstanding years of service.


Awards available to technicians through the Mark of Excellence Program include:

  • Toolbox Medallion – complete a minimum of four Gold Level Certifications
  • 500 earnPOWER points – achieve one Master Certification and 65% dealer-level MPVI
  • Top Zone Ranking – potential to earn additional earnPOWER points as well as the opportunity for a technician and guest to attend a zone banquet (top 20 technicians per zone)
  • Top National Ranking – Top 50 technicians nationally earn the national travel award for a 3-day/2-night trip to Detroit to meet with GM representatives and visit the GM Heritage Center.


The 2016 national winners were recently recognized in the June edition of the Automotive News’ Fixed Ops Journal. (Fig. 7)


Fig. 7


– Thanks to Diana Sancya

Fuel Odor or Leak from Underhood Fuel Feed Pipes

A fuel odor or fuel leak in the front of the vehicle may be noticed on some 2016-2017 CTS, Camaro; 2015-2017 Escalade/ESV, Tahoe/Suburban, Yukon/XL, and Corvette models equipped with a V8 engine (RPOs LT1, LT4, L83, L86) and 2014 Silverado 1500 and Sierra 1500 models equipped with a V6 or V8 engine (RPOs LV1, LV3, L83, L86). A fuel leak may be found around the bellhousing or valve lifter oil manifold (VLOM).


In addition, the vehicle may be hard to start, have poor fuel economy, or a wet underhood foam insulator.


These conditions may be caused by a fuel leak at one of the high pressure fuel rail pipe connections that was incorrectly installed during service of another engine component that required the fuel system to be opened, such as fuel rails, fuel injectors, high pressure fuel pump, etc.


TIP: The engine fuel feed intermediate pipes must be replaced during any service repairs that require one or more of the pipes to be loosened or removed.


If any of these conditions are found, find the fuel leak by installing dye, P/N 88861206 (in Canada, P/N 88861259), into the fuel system via the fuel filler neck. Idle the engine for 15 minutes and then remove the intake manifold and inspect for leaks.


Tightening a nut is not an approved procedure. If a leak is found at any nut location, follow these procedures:

  • Leak in pipe 2 – change only pipe 2 (intermediate pipe 2)
  • Leak in pipe 1 – change pipe 1 and pipe 2 (intermediate pipe 1 and 2)
  • Leak in pipe 3 – change only pipe 3 (fuel feed pipe). (Fig. 8)


Fig. 8


Ensure that all interfaces are clean and free of debris before installing. After installing the new pipes, idle the engine for three minutes and recheck for leaks.


Replace the engine insulator if it absorbed fuel or emits a fuel odor.


– Thanks to Tracy Lucas

Proper Oil Filter Use on the 1.4L Engine

The 1.4L turbocharged engine (RPO LUV) available in 2013-2018 Encore, 2016 Cruze (VIN P), 2013-2015 Cruze, and 2013-2018 Sonic and Trax models uses two different oil filters. It’s important to correctly identify and use the correct oil filter for the engine.


Two different suppliers provide the oil filter housing assembly for the 1.4L engine. Each housing assembly requires a different oil filter. The correct oil filter must be used based on the oil filter housing assembly application.


Use the VIN to identify the correct vehicle in the electronic parts catalog (EPC). For part number and usage, see Filter Kit, Oil in Group 01.836 in the EPC.


TIP: Install a new oil filter cap seal ring (Fig. 9, C) at each oil change. Ensure the oil filter cap (Fig. 9, B) is completely seated on the oil filter housing assembly (Fig. 9, D) and the filter (Fig. 9, A) fits properly in the housing. If the cap is not completely seated, an oil leak may occur. Do not overtorque the oil filter cap.


Fig. 9


– Thanks to Jeff Kropp

Lack of Performance in High Ambient Temperatures

Some 2013-2017 GM models may have a lack of performance in excessively hot and sustained ambient temperatures over 100° F (37.7° C) due to vapor buildup in the fuel feed line. DTCs P2635 (Fuel Pump Flow Performance) and P018B (Fuel Pressure Sensor Performance) may be set.


If the vehicle has not had a fuel pump replaced, refer to #PIP5411 for additional diagnostic information. It may be necessary to replace the fuel tank fuel pump module assembly. (Fig. 10)


Fig. 10


If the vehicle has had a fuel pump replaced, advise owners to use fuels with an octane rating higher than 91 and to refrain from periods of extending idling, if possible.


– Thanks to Richard Renshaw

Service Know-How

10217.07V – Emerging Issues

July 13, 2017


The latest service topics from Brand Quality and Engineering are reviewed, including a closer look at the new 2018 Camaro ZL1 1LE (Fig. 11) and timing chain removal and installation on the 3.6L LGX engine.


Fig. 11


To view Emerging Issues seminars:

  • Log in to
  • Select Resources > Video on Demand > GM STC > Search Videos; or
  • Select Catalog to search for the course number, and then select View > Take or Continue Course

Cadillac CT6 PLUG-IN Delivers Efficient Performance

The new 2017 Cadillac CT6 PLUG-IN (Fig. 1) is a new type of hybrid vehicle that delivers added performance with an efficient powertrain. The turbocharged 2.0L 4-cylinder engine (RPO LTG) and hybrid electric variable transmission (RPO MRD) combine with a lithium-ion high-voltage battery to offer a hybrid powertrain capable of 31 miles (50 km) of electric range and a 0-60 mph (0-97 km/h) time of 5.2 seconds.


Fig. 1


EV Mode


The CT6 PLUG-IN works to provide the most efficient use of both propulsion power sources — the 2.0L turbocharged engine and the high voltage battery. (Fig. 2) When fully charged, the high voltage battery is the dominant propulsion power source and the engine will turn on occasionally to provide supplemental power.)


Fig. 2


The vehicle operates in EV mode under light or moderate driving conditions for approximately 31 miles (50 km) and up to speeds of 78 mph (126 km/h). Under aggressive acceleration, the engine will turn on to assist the high voltage battery. The engine will turn off and EV operation will resume once the vehicle is driven under light or moderate driving conditions again. The EV Operation Gauge on the instrument cluster indicates when the engine will turn on. (Fig. 3)


Fig. 3


When the high voltage battery is depleted, the engine is the dominant propulsion power source and the high voltage battery will provide only supplemental propulsion power. The Total Power Gauge shows the current source of power.


The high voltage battery will store enough energy to provide some hybrid/EV driving or supplemental power. Full EV driving can only resume if the vehicle is plugged in to charge. The Battery Gauge shows the high voltage battery state of charge. When the gauge reads empty, the vehicle should be plugged in to charge the high voltage battery and to allow maximum EV operation again.


Drive Motor Battery System


TIP: Technicians must be fully trained to service the CT6 PLUG-IN. This includes completing all hybrid training. Technicians also must follow all safety procedures and have Personal Protective Equipment (PPE) and up to date certified Class 0 HV Isolation Gloves.


The high voltage hybrid/EV battery is installed from beneath the vehicle, into the rear storage compartment. (Fig. 4) The battery energy control module, a current sensor, and the high voltage contactors are located within the hybrid battery assembly.


Fig. 4


The high voltage battery contains 192 individual lithium-ion cells. Every two cells are welded together in parallel for a total of 96 cell groups, which are electrically connected in series. The battery cell groups are joined to form three distinct sections. The battery sections also contain two temperature sensors. Diagnostics and system status are communicated from the battery energy control module to the hybrid powertrain control module 2 through serial data.


Other components (Fig. 5) of the Drive Motor Battery System include:

  1. S15 Manual Service Disconnect
  2. T18 Battery Charger
  3. K10 Coolant Heater Control Module
  4. K1 14V Power Module
  5. T6 Power Inverter Module
  6. G1 A/C Compressor
  7. C4B Hybrid/EV Battery Section 2
  8. C4C Hybrid/EV Battery Section 3
  9. A28 Hybrid/EV Battery Contactor Assembly
  10. C4A Hybrid/EV Battery Section 1
  11. K16 Battery Energy Control Module


Fig. 5


Parts Restrictions


The following components are on TAC Restriction to assist the dealership during diagnosis as well as to gather valuable feedback:

  • Drive Motor Battery (high voltage battery)
  • Hybrid Powertrain Control Module 2 (HPCM2)
  • 4EL70 Hybrid Transmission
  • CT6 Drive Motor Power Inverter Control Module (PIM)
  • Accessory Power Module (APM)
  • Drive Motor Battery Charger (OBCM) and Charge Receptacle


Cooling Systems


The CT6 PLUG-IN is equipped with three fully independent cooling systems.


The hybrid/EV electronics cooling system is dedicated to cooling the power electronics components — including the power inverter module, battery charger, and the power module — using the auxiliary radiator, engine control module inputs, radiator fans and hybrid/EV electronics coolant pump.


The high voltage battery is cooled and heated with pre-mixed DEX-COOL. Only use GM pre-mixed DEXCOOL, as it contains deionized water required for the high voltage battery and power electronics cooling systems. Use of any other coolant could result in potential Loss of Isolation DTCs.


A refrigerant/coolant heat exchanger (chiller) and the A/C compressor cools down the high voltage battery. A high voltage heater inside the high voltage battery can also heat the coolant entering the high voltage battery when needed.


The passenger compartment heater system uses the engine radiator, the auxiliary heater coolant pump, passenger compartment heater coolant control valve, high voltage coolant heater control module and a heater core to provide warm cabin air.


2.0L Turbocharged Engine


The 2.0L turbocharged 4-cylinder engine (Fig. 6) is designed for greater efficiency and power. The turbocharger generates up to 20 pounds (138 kPa) of boost and its twin-scroll design helps optimize the usable power from the engine. The engine produces 265 horsepower and 295 lb.-ft. of torque.


Fig. 6


Electric Variable Transmission


The new 4EL70 transmission (Fig. 7) is a fully automatic, rear wheel drive, electric variable transmission (EVT). It includes an input shaft, three stationary and two rotating friction clutch assemblies, a hydraulic pressurization and control system, an electric fluid pump, three planetary gear sets, and two electric drive motors. An external torque dampener, bolted to the engine crankshaft, is splined to the transmission input shaft.


Fig. 7


The hydraulic system includes a high pressure electric fluid pump driven by an electric motor supplied with high-voltage current from the power inverter module. The electric pump maintains working pressure and control of the clutches when the engine is on and when the engine is off.


The three planetary gear sets, electric motor-generators, and other clutches together provide all-electric propulsion, electric variable hybrid transmission ratios, and fixed mechanical transmission ratios. (Fig. 8)


Fig. 8




The Regen-on-Demand system enables the driver to control energy regeneration using the steering wheel paddles. Regenerative braking takes some of the energy from the slowing vehicle and turns it back into electrical energy, which is stored in the high voltage battery.


Regen on Demand allows the driver to increase the amount of deceleration provided by regenerative braking by pressing the paddles on the back of the steering wheel. It can be used during sporty driving and when descending hills to slow the vehicle. It also enables one-footed driving using the accelerator pedal and the selected deceleration level, which can be convenient in stop-and-go traffic. Select a deceleration level from M4 (fastest) to M1 (slowest) using the shift lever and the paddles to adjust the creep speed.


Information Displays


Several information displays are available on the infotainment system that provide an overview of hybrid operation. Select the Green Leaf Energy icon on the infotainment Home page and then touch the Flow, Charging, or Info icon. (Fig. 9)


Fig. 9


The Power Flow screen indicates the current system operating conditions, showing the power flow between the high voltage battery and engine through the transmission.


The Charging screens show the Charge Limit and Charge Mode status.


The Energy Info screens show the energy use (electric and gasoline) since the last time the high voltage battery was fully charged as well as how the energy was used.


High Voltage Battery Charging


The high voltage battery pack capacity is 18.4 kWh, but by design, only approximately 75% of the battery is usable to power the vehicle. The battery pack requires approximately 13–17 kWh to fully recharge, depending on temperature and battery condition. (Fig. 10)


Fig. 10


The minimum electrical circuit requirements for charging the vehicle are 120 volts/15 amps or 240 volts/20 amps. The charging times vary, but it will take approximately 4.5 hours to fully charge using a 240 V, 16 A charging station or approximately 20 hours using the default setting of 120 V, 8 A with the portable charge cord. (Fig. 11)


Fig. 11


The vehicle can be programmed for three charging modes: Immediately, Delay Charge Based on Departure Time, and Delay (Electric Rate and Departure Time).


Charging settings also can be saved for the vehicle’s home location. These settings will be used whenever the vehicle is parked at its home location. The settings can be changed in the Energy menu by selecting Settings on the infotainment system.


The charging indicator on top of the instrument panel (Fig. 12) shows the current state of the charging process.

  • Short Flashing Green Light – The vehicle is plugged in but the battery is not fully charged. The flash rate increases from one to four flashes as the battery charges.
  • Long Flashing Green Light – The vehicle is plugged in but the battery is not yet fully charged. Battery charging is in Delay Mode.
  • Solid Green Light – The vehicle is plugged in. The battery is fully charged.
  • Solid Yellow Light – The vehicle is plugged in but not charging.
  • No Light – The vehicle is not plugged in or there is an issue with the portable charge cord or the electrical outlet.


Fig. 12




To fill the fuel tank, press the fuel door button on the driver’s door. The Wait to Refuel message will display on the Driver Information Center. When the Ready to Refuel message is displayed, the fuel door will unlock. Press and release the rear edge of the fuel door to open it.


Special Tools


The following new tools were released for the CT6 PLUG-IN.


– Thanks to Sherman Dixon, Blake Streling and Keith Newbury

  • [+]2017
  • [+]2016
  • [+]2015
  • [+]2014