Archive for August 2016

Updated Corvette Driveline Support Assembly Replacement Procedure

Slow engine cranking, a dead battery or a no start condition on 2014-2016 Corvette models equipped with an automatic transmission may be caused by a misaligned driveline support assembly (Fig. 1). The misaligned assembly can cause excessive pressure and damage to the engine crankshaft thrust bearing. (Fig. 2, #1)

2014 Chevrolet Corvette Stingray

Fig. 1



Fig. 2


If the driveline support assembly has been removed for a previous vehicle repair, the propeller shaft hub clamp must be realigned. Failure to properly align the driveline support assembly may push the crankshaft forward, removing any end play. The damaged thrust bearing typically fails approximately 3,000–5,000 miles (4,000–8,000 km) after the repair when the driveline support assembly was removed.


The driveline support assembly consists of a driveline support tube, with rear bell housing, and an internal propeller shaft assembly. The front of the driveline assembly mounts to the engine bellhousing. The driveline support assembly is specific to either automatic or manual transmission applications.


Any related warranty claims involving the driveline support assembly may be debited for improper workmanship.


Updated Procedure


The Service Information procedure for driveline support assembly replacement was recently updated for vehicles with an automatic transmission (Doc. I.D. #3462804).


The updated procedure includes tightening the propeller shaft hub clamp bolt (Fig. 3) to 130 Nm (96 lb.-ft.). Measure crankshaft end play with a dial gauge. (Fig. 4)



Fig. 3



Fig. 4


After test driving the vehicle, recheck end play. If there is no end play, the clamp bolt must be loosened and the crankshaft pushed rearward again.


New Video


A video on the updated procedure is included in the September 2016 Emerging Issues seminar (10216.09V) that is available on the GM Center of Learning. (Fig. 5)



Fig. 5


– Thanks to Jeff Strausser and Tracy Lucas

Take the 2016 Service Technician Satisfaction Survey Today

The 2016 Service Technician Satisfaction Survey is taking place now and technicians at all dealerships are encouraged to participate. GM and other automotive manufacturers co-sponsor this annual survey to collect feedback on service trends, satisfaction levels, dealership operational issues and the level of manufacturer’s support. The survey this year focuses on technician recruitment and retention in the dealership.


All GM Service Technicians, Technician Apprentices, and Maintenance Inspection Technicians (MIT) profiled in the Center of Learning should have received an email announcing the survey along with a link to the survey. The survey also is available at or by clicking the link on the home page of the GM Center of Learning. (Fig. 6) (In Canada, go to To complete the survey, you will need your 6-digit Dealer Code/BAC Code.



Fig. 6


The Service Technician Satisfaction Survey will be active from September 19 – October 14.


It shouldn’t take more than 15 minutes to complete. All survey responses are strictly confidential and will not be shared with your dealership.


Your feedback is very important. Please take this opportunity to provide your comments and suggestions about your experiences.


– Thanks to Lisa Scott, Diana Sancya and Chris Wallace

AFIT Adapter Cable Identification and Vehicle Application Chart

The Active Fuel Injector Tester (AFIT) Diagnostic Kit, essential tool CH-47976 (Fig. 7), is designed to test fuel injectors on port and direct injected engines going back to the 1996 model year. As new vehicle applications have been introduced, the kit has grown to include a number of available adapter cables, including for SIDI engine fuel systems (Fig. 8A) and the Duramax diesel engine. (Fig. 8B)


TIP: The AFIT Kit, CH-47976, was an essential tool for Tier 1, 2, 3, and 4 dealerships only. Tier 5 dealerships may order the tool at



Fig. 7 – CH-47976 


Fig. 8A – CH-47976-500A 



Fig. 8B – CH-47976-505 


An AFIT Vehicle Application Chart has been developed to help identify the correct cable adapters for each GM model.


The chart lists the model applications, engine RPO, cable components, type of communication, SENT (Single Edge Nibble Transmission) applications and Stop/Start applications.


Correct Connections


When testing an engine using the AFIT kit, do not connect the adapter cables to the vehicle until instructed to by the AFIT MCU (Main Control Unit). The MCU should be placed in the vehicle cab and plugged into the power adapter.


The DMU (Drive & Measurement Unit) should be placed in the engine compartment and connected to the vehicle’s 12-volt battery and to the MCU.


Select a vehicle on the AFIT MCU and then select an injector test. Follow the on-screen instructions/prompts on the MCU to connect to the vehicle. When prompted, with the ignition off, connect the DMU cable to the vehicle ECM harness connectors.


TIP: To help in determining which adapter to use, the AFIT will display the correct adapter during the testing process. The latest software must be used in order to display all correct adapter and cable selections.


Software Updates


Download the latest AFIT software through the Service Workbench selection of “Essential Tools – Software Updates” in GM GlobalConnect (U.S. only).


In Canada, GlobalConnect provides a Quick Link titled “Essential Tools – Software Updates” available from the Service page.


– Thanks to Chuck Berecz


Airbag Connector Seating

The airbag warning lamp may be illuminated on some 2016 Malibu (VIN Z); 2016-2017 CT6, Camaro, Volt; and 2017 LaCrosse, ATS, CTS, XT5, Escalade models, Colorado, Impala, Silverado, Tahoe, Suburban, Acadia (VIN N), Canyon, Sierra and Yukon models. One or more of the following airbag DTCs may be set: B0012, B0013, B0014, B0015, B0016, B0017, B0018, B0019, B0020, B0021, B0022, B0023, B0024, B001A or B001B.


The cause of the illuminated warning lamp may be an airbag warning lamp connector that is loose or not fully seated. (Fig. 9)



Fig. 9


Inspect the airbag connector for complete contact. If the airbag connector is not fully seated, disconnect and reconnect it. Verify the repair.


TIP: Any time the airbag connector is disconnected and reconnected, perform a “push/push” test (not a “push /pull” test) on the connector to ensure it is fully seated. (Fig. 10)



Fig. 10


– Thanks to Bob Wittmann

Hydraulic Brake Conditions on Electric/Hybrid Vehicles

There may be several brake system conditions on the 2016-2017 Volt and Malibu Hybrid (RPO HP4) that could be related to the hydraulic components. These types of hydraulic issues should not be overlooked when diagnosing a condition on electric/hybrid brake systems.


Misrouted brake line – A misrouted metal brake line may cause the line to kink (Fig. 11), which would reduce the brake apply pressure to the wheel. DTC C05AD (Brake Blending System Performance) may set. This condition could occur if the misrouted line hits the shock tower when the wheel is turned.



Fig. 11


Worn rubber brake hose – If the anti-rotation bracket is not seated into the hole properly, the rubber brake hose could rub through on the front wheel. (Fig. 12) This condition could lead to a loss of brake fluid and brake apply. DTCs C05AD, C0580 (Brake Booster Motor “A” Phase U-V-W Circuit Low), P05FF (Brake Pressure Sensor and Brake Pedal Position Sensor Correlation) may set.



Fig. 12


Twisted rubber brake hose – A Master Cylinder (MC) line from the Secondary Port to MC2 that is twisted 360 degrees (Fig. 13) may cause pressure to get trapped in the brake system. This condition may cause a concern during a light coast with a light brake apply at 45 mph (72 km/h). DTC C05AD may set along with illuminated ABS, traction control and Check Engine warning lamps.



Fig. 13


Bent brake caliper slide pins – If the right front bleeder screw is bent/cracked or the brake rotor shows uneven pad contact, check for a bent caliper guide pin. (Fig. 14) A bent pin may cause the brake warning light to illuminate or set DTC C05AD.



Fig. 14


Leak at caliper brake hose – A brass crush washer can only be used one time. (Fig. 15) Reusing a brass crush washer may cause a leak. Look for the crush washer to have an oval shape and witness lines indicating multiple use. Always discard washer and replace with a new brass crush washers.



Fig. 15


A leak also may be due to the crush washer bolt being cross-threaded (Fig. 16) and retightened. When tightening the crush washer bolt, make sure to finger tighten the bolt to guide to avoid cross-threading when reinstalling.



Fig. 16


– Thanks to Keith Newbury

Special Programming Instructions for Service Replacement Radios

A new service replacement radio has been released for 2014-2016 Encore, Verano, Camaro, Caprice, Cruze, Equinox, Malibu, Orlando, SS, Volt, Terrain; and 2016 Cascada models equipped with Radio RPOs UFU, UFU/UP9 or UHQ/UP9. Due to this change, the radio part number received may not be the same part number as the one that was ordered. In addition, certain service replacement radios do not require USB programming.


If USB programming is attempted on a replacement radio that does not require USB programming, SPS error code E4411 or E2907 will be displayed in TIS2Web and the USB programming will be prevented.


The following service replacement radios do not require USB programming at this time: 42481354, 84062099, 84062126, 84064072, 84064073, 84064074, 84064075, 84064076, 84064077, 84073998, 84156022, 84156023, 84156665, 84156666, 84156669, 84156924, 84159089, 84159090, 84159093, and 84159094.


Skip the usual USB programming instructions that are outlined in the Service Information procedure for these service replacement radios and only perform SPS programming with TIS2Web. For any other service replacement radios, follow the normal Service Information instructions to install and program the radio.


TIP: The listed Chevrolet service replacement radios will have a new start-up screen (Fig. 17), which is a design characteristic of these new Chevrolet radios.



Fig. 17


– Thanks to Jamie Parkhurst

Testing for Accurate Fuel Economy Results

Owners of 2010-2017 Equinox and Terrain models equipped with the 2.4L engine (RPO LAF, LEA) and front-wheel drive may have questions about the actual fuel economy of their vehicle. In most cases, a small amount of city driving will quickly bring down the average fuel economy result of an individual vehicle. Owners who have a concern about poor fuel economy should be made aware of the impact driving style and driving conditions have on fuel economy results.


To properly perform a fuel economy evaluation of a vehicle to ensure accurate fuel economy results are being achieved, review the following tips.


Initial Fuel Economy Evaluation

•     Review daily driving habits, including distance traveled, types of roads and typical speeds.

•     Check for stored DTCs

•     Check for proper tires pressures. The Driver Information Center (DIC), if equipped, provides accurate tire pressure readings.

•     Raise the vehicle and make sure the rear wheels turn freely on front-wheel drive models. Check that the parking brake is not dragging.

•     Document temperature and climate conditions and the current seasonal fuel blend being used. Top Tier fuel is recommended for optimal fuel economy and engine performance.


Actual Driving Evaluation

•     Fill the tank with fuel using the three click procedure: Add fuel until the pump nozzle shuts off automatically, count to five and fill again until the pump shuts off, count to five and fill once more until the pump shuts off a third time.

•     Record the odometer reading and reset the trip odometers.

•     On a flat road where a steady speed can be maintained, drive the vehicle at a steady speed for five miles. If a flat road is not nearby, use a road without large hills.

•     Note any wind conditions.

•     Bring the vehicle up to a speed between 50 to 65 mph (80 to 105 km/h) and set the cruise control.

•     Scroll through the Trip menu on the DIC (Fig. 18), if equipped, to display the Average Fuel Economy reading. Reset the Average Fuel Economy reading under the Trip menu on the DIC by holding the SET/CLR button (Fig. 19) until the display reads 22 mpg (10.7 L/100km). This is the “seed’ value that the system starts with and then learns the actual fuel economy from this value. It will take several miles (or kilometers) for the Average Fuel Economy to stabilize and provide a true value.


Fig. 18



Fig. 19


•     On average for 4-cylinder models, at 55 mph (89 km/h), the Average Fuel Economy should be 36 mpg (6.5 L/100 km) and, at 60 mph (97 km/h), it should be 33 mpg (7.1 L/100 km).

•     Reset the display and try different speeds and conditions.

•     Once enough distance is driven, top off the fuel tank following the three click procedure using the same fuel station and fuel pump. Record the odometer reading and calculate the fuel economy from the number of gallons/liters pumped.

•     Observe and diagnose any performance issues such as rough idle, excessive vehicle drag when coasting, or poor driveability.


Review the complete road test findings with the customer to ensure the test and results are fully understood.


– Thanks to David Rutkowski

Lane Keep Assist Steering Intervention

Some of the latest active safety features available on GM models employ sophisticated camera-, radar- and sensor-based technologies to help assist drivers avoid a collision or reduce its impact.


Lane Keep Assist (RPO UHX) — available on many newer GM models — uses a number of advanced components to help drivers avoid crashes due to unintentionally drifting from their lane. The components include:

• Front View Camera Module • Lane Keep Assist Switch/Control Indicator (Fig. 1) • Instrument Cluster/Vehicle Direction Display • Radio (for warning beeps/chimes) • Safety Alert Seat (if equipped) • Yaw Rate Sensor • Electric Power Steering



Fig. 1


How It Works


For Lane Keep Assist to begin providing assistance, the following must occur:

• Vehicle speed is between 37 mph (60 km/h) and 111 mph (180 km/h) • Lane markings are clearly visible • The system is turned on using the On/Off button • Lane marker width and radius meet pre-set criteria (not too wide or narrow and the curve of the road is not too tight)


The camera detects the lane markings on the road. The front view camera module communicates via serial data with the instrument cluster, radio, and memory seat module to request visual indicators and, in rare instances, audible or haptic alerts. The Lane Keep Assist indicator on the instrument cluster is green when a lane marking is detected and other operating conditions have been met, indicating that the system is in the “ready to assist” mode.


TIP: If the system cannot detect lane markings, it may be due to snow, rain, or other driving conditions, or the windshield area in front of the camera or the camera lens may be blocked by fog, dirt, damage to the windshield or other elements. The vehicle should be kept clean for proper operation.


Stage 1 — Lane Keep Assist Intervention


The system has two driver interventions. When it is determined that the vehicle has unintentionally approached a detected lane marking without a turn signal being activated in that direction, and the driver has not actively responded by either steering, accelerating, or braking, the electric power steering system will provide a gentle, momentary correction (torque input to the steering) to help guide the vehicle back on course. Lane Keep Assist does not continuously steer the vehicle. This steering pushback is the first stage of warning/intervention.


TIP: The Lane Keep Assist indicator will turn amber when torque is applied to the steering. There are no chimes or haptic seat warnings at this point of Lane Keep Assist operation.


The steering intervention is based on the forward looking sensor outputs, such as lateral offset of the vehicle, relative yaw angle and time to line crossing. In addition, other vehicle dynamics signals are needed, e.g. velocity, steering angle, yaw rate, for the purpose of a driver suppression of the steering intervention. The electric power steering uses a torque sensor to detect driver inputs and relays that information to the front view camera module.


Stage 2 — Lane Departure Warning


If active driver steering is not detected, the second stage warning/intervention is a Lane Departure Warning (RPO UFL) that may activate as the vehicle is crossing the lane marking, alerting the driver through several beeps or a Safety Alert Seat vibration, if equipped. The seat vibration will take place on the side of the seat where the lane departure occurs. In addition, the amber Lane Keep Assist indicator will flash.


The Safety Alert Seat must be turned on in the vehicle settings in order for haptic seat feedback to occur.


TIP: Most commonly, the driver applies more torque to the steering wheel to overcome the Lane Keep Assist intervention. As a result, Lane Departure Warning alerts are rare because they only occur if the driver does not put significant torque onto the steering wheel and the Lane Keep Assist steering intervention was not enough to prevent a lane departure. This circumstance tends to happen only at the entrance to some curves.



Testing the System


Lane Keep Assist intervention may not occur when expected by some drivers while approaching a lane marking. Lane Keep Assist replaced Lane Departure Warning for 2016 (although Lane Departure Warning remains a key component) and operation is slightly different.


For example, if the driver tries to “test” the Lane Departure Warning alert and overcomes the steering correction so that the vehicle intentionally crosses the lane marker, the Lane Departure Warning system may interpret this as active steering and, in many cases, may not provide an alert. Consequently, alerts will occur less frequently as the Lane Keep Assist system provides steering input than with the previously used Lane Departure Warning system.


TIP: If a customer expresses concern that a Safety Alert Seat vibration or warning chime did not occur, verify that there are not any issues with the vehicle’s operation or DTCs set and then explain the proper operation of the Lane Keep Assist and Lane Departure Warning systems.


External Influences


Proper functionality of the Lane Keep Assist system may be affected by outside factors, including:

• Nearby vehicles ahead (tailgating) • Sudden lighting changes, such as going through a tunnel • Banked roads • Poor lane markings


Should these conditions exist, the driver is advised to turn off the system. This does not indicate a system failure. Also, drivers should not use Lane Keep Assist while towing a trailer or traveling on slippery roads.


Here’s a video demonstration of how the system works. (Fig. 2)



Fig. 2

– Thanks to Charles Green and Ray Kiefer



All-New 2017 Buick LaCrosse is Here

The all-new longer, lower and wider 2017 Buick LaCrosse debuts the new face of Buick with the return of the three color Buick tri-shield insignia set against darkened waterfall grille bars. (Fig. 3) The 2017 LaCrosse is about 300 pounds (136 kg) lighter than the current LaCrosse and is available in front-wheel drive and all-wheel drive (AWD) models.


2017 Buick LaCrosse

Fig. 3




The LaCrosse features the all-new 3.6L DOHC V6 engine (RPO LGX) with variable valve timing and direct injection. It generates 305 horsepower and 268- lb.-ft. of torque and is paired with the new Aisin AF50-8 8-speed automatic transaxle (RPO MRC). To increase fuel efficiency, the engine uses Active Fuel Management (AFM), which deactivates two cylinders under certain conditions, and advanced Stop/Start technology that turns off the engine under certain conditions when the vehicle is stopped. It only takes the Stop/Start system approximately 0.3 seconds to start the engine.


The Aisin AF50-8 is a compact, lightweight, electronically controlled 8-speed automatic transaxle that employs a Ravigneaux-type planetary gear set. (Fig. 4) It also employs a high-precision clutch hydraulic control system for a smooth, highly responsive gear shift feel. The Transmission Control Module (TCM) uses adaptive learning, adjusting the current output to the various pressure control solenoid valves, to maintain the originally calibrated shift timing.



Fig. 4


Selecting a gear is done with the shift-by-wire Electronic Precision Shift (EPS) gear selector (Fig. 5), which eliminates the mechanical connection to the transmission. The lever operates like a premium joystick, and the paddle shifters on the steering wheel can be used for a more engaging driving experience.


2017 Buick LaCrosseFig. 5


TIP: A noise may be heard when transitioning into Park, especially when parking on a hill. The noise may be due to the ABS pump. If the vehicle has not come to a complete stop when the vehicle is placed in Park, the wheel speed sensors will detect speed and the ABS pump will be activated to apply the brakes before the parking pawl is engaged. This sound is a normal operation. Drivers should be reminded to bring the vehicle to a complete stop before shifting into Park.


The available AWD system with Active Twin Clutch (Fig. 6) on the LaCrosse electronically splits the torque as needed between the rear wheels using twin clutches to provide additional traction, stability and control versus a 50/50 split in a single clutch system. The active torque bias adds stability across all driving conditions while a fuel economy benefit is realized by not pushing torque when it is not needed.


2017 Buick LaCrosse AWD Suspension

Fig. 6




Two front suspension systems are available on the LaCrosse: the standard McPherson strut front suspension (RPO GNA) and the available HiPer Strut front suspension (RPO GNB). (Fig. 7) Features of the two suspensions include:

1. HiPer Strut vs. McPherson Strut 2. Same body attachment points 3. Kingpin axis 4. Wheel center 5. Spindle length 6. Same body attachment points



Fig. 7


With the HiPer Strut system, ride characteristics are controlled by the Electronic Suspension Control system that individually controls the damping force of each of the four shock absorbers. Changes to the damping forces can be accomplished within milliseconds. The HiPer Strut front suspension offers a number of benefits over traditional systems, including less torque steer, reduced smooth road shake, increased cornering power, and enhanced ride and handling performance. The rear suspension is an independent link type. Rear suspension adjustment is achieved through adjustable toe links and lower control arms.


Interior Features


The LaCrosse offers three instrument clusters with different Driver Information Centers (DIC) that offer a wealth of vehicle data.


Instrument cluster RPO UDC has a one-color multifunction DIC display that has several screens that can be scrolled through by turning the trip reset stem.


Instrument cluster RPO UDD has a full-color multifunction DIC display that is tightly integrated with the vehicle’s infotainment system and is highly reconfigurable.


Instrument cluster RPO UHS is a reconfigurable cluster with four different themes available. (Fig. 8) The cluster has an LCD display with DIC elements located in various zones of the display, depending on configuration.


2017 Buick LaCrosse

Fig. 8

In order to make the interior cabin quiet and comfortable, the QuietTuning® process has been employed in the LaCrosse to reduce, block and absorb noise and vibration. QuietTuning enhancements include ultradissipative materials and Active Noise Cancellation.


The latest edition of the Buick IntelliLink system is displayed in a new, frameless 8-inch (203 mm) diagonal color touchscreen located at the center of the instrument panel. (Fig. 9) It was designed with fewer buttons and controls for more intuitive use. Many features can be controlled via voice commands through a button on the steering wheel.



Fig. 9


Safety Features


The available driver assistance features on the LaCrosse include Forward Collision Alert (FCA), Lane Departure Warning (LDW), Lane Keep Assist (LKA), Side Blind Zone Alert (SBZA), Lane Change Alert (LCA), Front Pedestrian Braking (FPB) and/or Forward Automatic Braking (FAB). All of these features are designed to help drivers avoid a crash or reduce crash damage.


In addition, Adaptive Cruise Control is available. It allows the driver to select the cruise control set speed and following gap so the vehicle automatically maintains a set distance from a detected vehicle in front of the LaCrosse.


Automatic Parking Assist also is available. It searches for and steers the vehicle into parallel and perpendicular parking spots. When using APA, the driver must still shift gears and control the brakes and accelerator.



For more information about the new 2017 LaCrosse, refer to Bulletin #16-NA-230.


– Thanks to Sherman Dixon and Aaron Huston


Lumbar Back Massage Performance

The new 2017 LaCrosse offers driver and front passenger seats with a massage feature (RPO AF6, AKE). Some passengers may feel that the lumbar back massage is inoperative or the performance is poor.


The intensity of the lumbar back massage is aligned with the lumbar adjustment of the seat. If the lumbar adjustment of the seat is in a decreased setting, the perception may be that the back massager is not functioning properly.


Advise customers that the intensity of the back massage can be changed by increasing or decreasing the lumbar adjustment prior to activating the massage function. Use the lumbar adjustment control (Fig. 10, #1) and the massage button (Fig. 10, #2) located on the side of the seats to make any adjustments.



Fig. 10


– Thanks to Aaron Huston

Check Dealership IT Guidelines before You Buy; Windows 10 Now Supported

If you’re thinking about buying a new computer for use in the dealership service department, check the GM Dealer Infrastructure Guidelines first. A revised version of the guidelines was recently released and is available at Click the Techline IT Solutions tab and then GM IT Standards. In Canada, the IT guidelines are in the Service Library under Service Department on GlobalConnect.


Before purchasing a desktop PC or laptop PC for use in the dealership, the guidelines should be reviewed to ensure that the computer meets the recommended hardware and software specifications needed to properly run all Techline applications.


Windows 7 Pro or Windows 10 Pro


The guidelines specify that the computer must include business grade hardware that meets or exceeds the minimum specification with Intel Processors and runs the Windows 7 Professional 64 bit or Windows 10 Professional 64 bit operating system.


What’s Supported


Prior to purchasing a business grade computer, review the table on page 2 for what is “supported and not supported” for Techline applications as well as the recommended guidelines for purchasing new desktop PC and laptop PCs on pages 3–4. (Fig. 11)



Fig. 11


Techline does not support consumer branded PCs, built by hand and/or home grade operating systems typically used for multi-media or gaming purposes. Techline also does not support AMD processors. Extensive testing of consumer targeted computers and operating systems show they are not suitable for diagnosing vehicles using Techline software applications. Techline applications are considered business class and are intended to run on a business grade computer.


Any questions about computer specifications in the U.S. and Canada can be directed to the TCSC at 1-800-828-6860 (English) or 1-800-503-322 (French).


– Thanks to Lisa Scott



GDS 2 Core and Diagnostic Package Updates

The Global Diagnostic System (GDS) 2 receives periodic core updates throughout the year. The latest version, 15.0.14700, released on August 29, 2016 contains several software bug fixes as well as major application changes that impact the way GDS 2 looks and functions. These updates are available when logging into TIS2Web and launching GDS 2 from the TIS2Web home page.


In addition to the periodic core update, GDS 2 receives an updated diagnostic package once a month. The current diagnostic package is GM Global v2016.9.1 and includes updated information on individual vehicle platforms. The updated diagnostic package is available in GDS 2 by clicking the “Update” button or selecting “Manage Diagnostic Packages.”


The version numbers can be seen in the lower left corner of GDS 2. (Fig. 12)



Fig. 12


These updates work together so it’s important to have the latest core version as well as the latest diagnostic package installed to ensure the all fixes are in place. Using the new software updates minimize the chance of encountering errors when launching or using GDS 2.


If any issues are encountered with GDS 2, update both the core version and the diagnostic package. If any issues are not resolved after performing the updates, contact the Techline Customer Support Center (TCSC) at 1-800-828-6860 (English) or 1-800-503-3222 (French).


– Thanks to Chris Henley



Night Vision Working in Daylight or Inoperative

The Night Vision feature (Fig. 13) on some 2016 CT6 models may be on during daylight hours, or it may be inoperative and a Service Night Vision System message may be displayed on the Driver Information Center.



Fig. 13


Daylight Condition


The Night Vision Manufacture Enable Counter (MEC) may be set too high, which causes the needed parameter inputs that send information to the module for operation to be ignored.


Monitor the MEC counter using the Identification Information screen on GDS 2. Cycle the ignition switch to decrement the MEC. Once the MEC is at zero, the Night Vision system will only work when the ambient light status message reports it is dark.


Inoperative Condition


If a DTC is set in the Night Vision module, follow the appropriate Service Information diagnostic procedure.


If there not any DTCs set, inspect the Night Vision video cable connection at the back of the instrument panel cluster. Remove the cluster and check that the cable connection is securely inserted into the back of the cluster.


– Thanks to Blake Streling


Cleaning Excessive Carbon from Sticking Valves

2000-2015 GM passenger cars and light-duty trucks equipped with gasoline engines that experience engine misfire, rough idle, extended crank or crank/no start conditions may be the result of major carbon build-up on the intake and/or exhaust valves. One or more misfire DTCs may be stored in the Engine Control Module (ECM). Excessive carbon build-up on the intake and exhaust valves is often due to fuel contamination or incomplete burning of the fuel. (Figs. 14, 15)



Fig. 14



Fig. 15

When the engine is cold, the compression on multiple cylinders may be at 0 PSI. The engine also may pop through the intake or exhaust while cranking and the spark plugs may be fuel fouled. Some engines also may experience valve damage or cam followers that are out of position.


If these conditions are found, follow the misfire diagnostics in the appropriate Service Information. If valve damage is present or there are cam followers out of place, perform the engine mechanical repairs necessary to correct the condition. Also perform a valve cleaning to free up the sticking valves and to remove carbon from the valves and pistons.


Valve Cleaning


The valve cleaning procedure requires adding a bottle of GM Upper Engine and Fuel Injection Cleaner into the engine with RPM off idle enough to prevent the engine from stalling (typically around 2,000 RPM). It’s recommended to induce the cleaner through the throttle body with Kent-More Tool # J-45076 or J-35800-A or equivalent.


TIP: Extreme care must be taken not to hydro-lock the engine when inducing the cleaner, especially if it is induced without Kent-Moore Tool # J-45076 or J-35800-A or equivalent. If too much cleaner is induced at too low of a RPM, or if the engine stalls by inducing too much cleaner at once, the engine may hydro-lock and bend a connecting rod(s).


Tool # J-45076, originally released to Cadillac dealerships but now discontinued, includes the pressurized canister (Fig. 16, #1) and throttle body cleaning adapters. (Fig. 16, #2) The J-35800-A is another pressurized canister that can be used. If these tools are not available, use equivalent tools to perform the cleaning procedure.



Fig. 16


After allowing the cleaner to soak with the engine off for 2.5 to 3 hours (do not let the cleaner soak for more than 3 hours as remaining deposits may start to harden up again), add a bottle of GM Fuel System Treatment Plus to the fuel tank and fill the vehicle with a Top Tier gasoline. Test drive the vehicle extensively to circulate the GM Fuel System Treatment Plus. Once repairs are complete, change the engine oil and filter.


For more information about Top Tier gasoline, go to or refer to Bulletin #05-06-04-022.


A training video covering valve cleaning was included in the January 2013 Emerging Issues seminar (U.S.) and the March 2013 TAC Talk program (Canada). Refer to #PIP5029G for additional information and part numbers.


– Thanks to Tim Lightfoot


Service Know-How

10216.09V – Emerging Issues

September 8, 2016


The latest service topics from Brand Quality and Engineering are reviewed, including information on replacement of the Corvette driveline support assembly and how to adjust the shift cables on a 2016-2017 Cruze with a manual transmission. (Fig. 17)



Fig. 17


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
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