Archive for March 2016

R-1234yf Refrigerant Rollout Coming in 2017 Model Year

A number of 2017 Chevrolet, Buick, GMC and Cadillac models will join the current Cadillac XTS and Chevrolet Spark EV in using the new air conditioning refrigerant R-1234yf. R-1234yf is an environmentally friendly alternative to R-134a refrigerant, (Fig. 1) which is a greenhouse gas that has been cited as contributing to climate change. R-1234yf has a 99.7% lower Global Warming Potential (GWP) than R-134a. It is the industry accepted solution for a low GWP refrigerant.


The following 2017 models are currently targeted to receive R-1234yf in the North American market: Chevrolet Camaro, Cruze, Malibu, Colorado, Silverado, Tahoe and Suburban; GMC Acadia, Canyon, Sierra and Yukon models; Cadillac ATS, CTS and XT5; and Buick Cascada and LaCrosse. There will be more vehicles added for the 2018MY.


F01 r1234yf tank

Fig. 1


The US Environmental Protection Agency’s (EPA) motor vehicle greenhouse gas regulations require improvements in overall fuel economy and the use of R-1234yf will play a considerable role in helping GM vehicles achieve these targets under the new regulations. The new refrigerant has been tested and studied extensively by many organizations, including SAE International, the US EPA, regulatory and scientific organizations globally as well as every major automotive manufacturer. All of these groups agree that R-1234yf is a safe and environmentally friendly alternative to R-134a.


Differences in Refrigerants


While R-1234yf is very similar to R-134a, there are some important differences. R-1234yf is considered a mildly flammable gas and should not be serviced near any open flame or significant source of energy (e.g., welding). Like all automotive refrigerants, it is illegal to release R-1234yf into the atmosphere. In the case of an unintentional release, the immediate area should be ventilated; taking additional care to ventilate pits or low areas as the refrigerant is heavier than air and can collect in these areas.


R-1234yf has thermodynamic properties similar to R-134a, so system diagnosis is similar to R-134a systems. Refer to the appropriate Service Information for the latest diagnostic and repair procedures.


Special Tools


Existing R-134a equipment cannot service R-1234yf due to fitting differences, refrigerant mixing and safety requirements. The following tools needed to properly service R-1234yf systems will be shipped to U.S. dealerships in March and April. Cadillac and a limited number of Chevrolet dealerships already have these tools.


Screen Shot 2016-03-25 at 10.26.26 AM


PAG Oils


There are multiple refrigerant PAG oils released by GM Engineering to service GM vehicles built with R-1234yf. Be sure that the correct PAG oil as specified in the Service Information is the only PAG oil used during repairs. R-1234yf PAG oils cannot be mixed with or substituted for one another.


TIP: GM’s universal compressor oil released for R-134a applications cannot be used in R-1234yf applications and there are no aftermarket offerings approved for GM service use.


The same car line can use different PAG oils depending on the vehicle powertrain so always refer to the appropriate Service Information for the correct PAG oil part number to be used.


– Thanks to Chris Semanisin



GDS 2 Update Released

A number of changes to GDS 2 covering MDI and MDI 2 connections as well as graphing features are included in the recently released GDS 2 version 15.0. Here’s a summary of the changes you’ll see in the latest GDS 2 software.




The latest release includes multiple changes to the GDS 2 preferences. The column widths and locations of all tables in GDS 2 can be retained if the Save Modified Column Width and Order box is checked under the Column Width and Order setting. To reset the column width and order and clear the personalized table settings, press the Reset button. (Fig. 2)


F02 preference settings

Fig. 2


Vehicle Selection


The vehicle selection screen is now integrated with a new version of device explorer, which allows users to switch the J234 device type (MDI) more efficiently. The Device Type tab has been moved from the preferences settings to the vehicle selection screen. If any connection issues are detected, it will display an error message.


The device explorer is launched using the Select Device button. It also makes connections to the MDI/MDI 2 if the device is connected via USB.


When a device is connected, the device type name will be displayed at the top of the Vehicle Selection screen and in the lower right of the status bar. (Fig. 3) If an MDI or MDI 2 is connected, the device type name and a serial number is shown.


To select a different device, disconnect the device by clicking the Disconnect button. (Fig. 3)


F03 select device

Fig. 3


Data Display


Under the Data Display applications, the order of parameters is retained for the duration of a diagnostic session. Click the Reset Parameter Order button to resort the parameter list in the default order.


A new Change Scale button has been added under the Line Graph tab. A new editor allows users to type in min/max values (Y axis value) for each line graphed parameter. (Fig. 4)


F04 line graph

Fig. 4


DTC Applications


In the DTC applications, DLC Pin information has been added to the output. If the J2534 device does not support the required pins, the status indicates that the pins are not supported. (Fig. 5)


F05 DLC pin

Fig 5


The HTML report for the vehicle-wide DTC test lists all electronic control units (ECU) being tested, even if DTCs are not stored. New timestamp information also is included in the Report Creation Date.


The HTML reports also have the following new information listed in the header: VCI Serial Number, Vehicle Session Creation Date, Test Start Time, and Slider Position Time.


To ensure you are using the updated GDS 2 software, open GDS 2 through TIS2Web.


For assistance, contact the Techline Customer Support Center (TCSC) at 1-800-828-6860 (English) or 1-800-503-3222 (French).


– Thanks to Chris Henley

Windows 10 Incompatibility Update

GM is actively working to certify all Techline applications for compatibility with Windows 10 in a timely manner with a goal of ensuring users will be eligible to receive the free upgrade to Windows 10. While Microsoft is actively encouraging users of Windows 7 and 8.1 to upgrade to Windows 10 at this time, they have announced support for the previous versions until 2020 and 2023 respectively.


The GM Dealer Infrastructure Guidelines currently call for not updating to the new Windows 10 operating system until GM communicates applications are compatible.


Decline License Agreement for Automatic Updates


If for any reason the Windows 10 update is automatically pushed to a computer in the dealership, the Microsoft End User License Agreement (EULA) must be accepted before the installation will be completed. Click DECLINE to abort the windows 10 update. (Fig. 6) This will ensure the computer will remain in compliance with the GM Dealer Infrastructure Guidelines.


F06 decline button

Fig. 6


If you have upgraded a computer to Windows 10 within the last 30 days, uninstall instructions for Windows 7 and Windows 8.1 users were included with the recent GlobalConnect message Windows 10 Incompatibility with Dealer Applications.


– Thanks to Lisa Scott

New TAC Phone Prompts Speed Service

Nothing is more valuable to technicians than time. That’s why the U.S. GM Technical Assistance Center (TAC) phone prompts are designed to quickly get callers to the appropriate group when calling.


Based on feedback from Detroit-area dealers, Dealer Fixed Operations Advisory Board (DFOAB) dealers, and Service Manager Surveys, TAC recently made the following changes to the phone prompts:

• Removed unnecessary layers and selections

• Clearly identified the need for a TAC consultant (vehicle concerns) vs. a Techline consultant (module programming, error codes, VCI, GDS 2, Tech 2 concerns)

• Reordered the prompts to be similar to TAC call volume, so higher volume call types are at the beginning of the phone prompts

• Renamed several prompts to include the names of common call types, such as radio, OnStar, transmission, steering, and suspension.

• Removed dedicated phone prompts for older vehicle support and listed the names of the typical Medium Duty Truck models supported by TAC



These enhancements will be included in phase 1 of the TAC call prompt updates that will be implemented in mid-March. Additional enhancements/phases are also being considered.


Printable Phone Prompts Chart


All of the updates are highlighted in the prompt chart, which can be printed as a quick reference. The latest TAC phone prompt chart (Fig. 7) is also accessible via the Service Forms section of the GlobalConnect Service tab and the latest version of Bulletin #08-00-89-014.


F07 tac prompts

Fig. 7


Action Centers


TAC Action Centers are put in place to provide special support to the launch of new GM models. Specially trained TAC consultants handle Action Center calls. As these TAC cases are created, Action Center facilitators work closely with GM Brand Quality, Engineering, and Manufacturing to understand the causes of each case.


When a new TAC Action Center is created to support the launch of a new model, a related GlobalConnect message is sent to dealerships announcing the new model launch and TAC Action Center. For assistance on one of these new models, select the #2 Action Center Prompt in order to be routed to a specially trained TAC consultant.


– Thanks to Jamie Parkhurst and Elizabeth Belland

Storing and Using Special Tools in the Dealership

It’s simple but true: time is money. If a service department isn’t organized, technicians can waste a lot of valuable time searching for essential and special tools or using the improper tools for proper repairs. Tools are an investment. Organizing, storing and maintaining those tools can make a positive impact on the dealership’s productivity.


Feedback from dealership surveys regarding tool organization indicated that 77% of service managers and 90% of technicians felt their dealership could improve how their tools were organized. (Fig. 8)


F08 tools

Fig. 8


GM offers several ways for dealerships to get organized, including a variety of storage systems and in-dealership tool management assistance along with the GM Special Tools Organization website managed by Bosch. The best practices found with a successful tool organization program are:

• Assigning a tool organization supervisor

• Using a managed tool organization system, such as the GM Special Tools Organization website

• Dedicating accessible storage space

• Implementing a physical tool storage system

• Following a regular tool maintenance program




Return on Investment


How much productivity is lost by searching for special tools? On, there is a Return on Investment (R.O.I.) calculator that helps determine that. Click the Return on Investment link on the left side of the page to view the calculator. Fill in the estimated time spent looking for a tool and the number of technicians in the service department to see how much annual saving can be found through with a proper tool organization system.


For example, if three technicians spend just two less minutes per day looking for tools, it can lead to an annual savings of more than $16,000. (Fig. 9)



Fig. 9


Storage Options


Using the right storage system makes it possible to never misplace a tool again or spend valuable time digging through piles of tools.


When determining the kind of tool storage system that will work best in your dealership, consider the how much space is available, security of the area, how accessible it is, and the amount of tools in inventory.


GM Dealer Equipment offers tool storage cabinet systems, case and shelf systems for larger items (Fig. 10) or multiple tools (Fig. 11), tool peg-board systems (Fig. 12), and mobile cart systems. (Fig. 13)


F10 tool cabinet 5

Fig. 10


F11 tool cases

Fig. 11


F12 tool board

Fig. 12


F13 tool chest

Fig. 13


Tool Organization Services


The tool organization services available through Bosch range from complete planning and configuration to tool inventory set up, installation, and data entry of your inventory into the tool organization system.


These services include the assistance of organization specialists who are available to come to the dealership and identify, inventory, sort and organize all special tools in a simple, efficient, easy-to-use system. (Fig. 14)


F14 tool org image

Fig. 14


Watch the video (Fig. 15) below to learn more about tool organization options.


F15 tool video

Fig. 15


For more information, go to or click the link in the Global Connect/Service Workbench.


– Thanks to Chuck Berecz

Forward Lamp Harness Water Intrusion

On some 2016 Camaros equipped with the 3.6L engine (RPO LGX) and without the Track Performance package (RPO Y4Q), the engine cooling fan may intermittently stop working and the Check Engine lamp may illuminate. DTCs P0480 (Cooling Fan Speed Output Circuit) or P0691 (Cooling Fan Speed Output Circuit Low Voltage) may set. These conditions may be caused by water intrusion into the forward lamp wiring harness.


If the engine is continually running with an inoperative cooling fan, the engine may overheat, causing severe engine component damage.


If the harness is stretched or side loaded, where the cooling fan module connector plugs in, water may be allowed to wick down the harness, past the weather pack seals, and into the connector. Over time, the terminals inside the connector as well as the harness may become corroded. (Fig. 16) As the corrosion builds, the engine cooling fan may become inoperative.


F16 connectors

Fig. 16


Inspect the forward lamp wiring harness to cooling fan module connector for moisture and corrosion. If any is found, the fan control module and forward lamp harness should be replaced. If no moisture or corrosion is found, refer to the appropriate Service Information for additional diagnostic information.


TIP: If the harness is replaced, only one harness is needed per vehicle. Use the appropriate harness based on the vehicle headlamp type.


– Thanks to Matt Bierlein

Auto Heated and Auto Heated/Ventilated Seats Diagnostic Tips

The 2016 ATS, CT6, CTS, Escalade models, SRX, and XTS feature available automatic heated seats. The 2017 XT5 features available automatic heated and ventilated seats. These models are also equipped with automatic climate controls. (Fig. 17)


F17 heated seats CT6

Fig 17


In order to properly diagnose these seat features, it’s important to understand how they operate.


The auto thermal seat function activates the heating or ventilation based on outside air temperature and the cabin air temperature control error, which is the difference between the cabin air target temperature and actual cabin air temperature. If the cabin is very cold, a high seat heating level is activated. When the cabin warms up, the seat heating level is automatically decreased. The functionality is the same for a cool-down scenario. When the heating or cooling is completed, the seats stay on at a minimum level.


The auto thermal seat function initializes when the ignition is turned on. The system is given some time to stabilize — 30 seconds for 2016 models and increased to 10 minutes for 2017 models. After the stabilization period, seat levels are only allowed to decrease.


If the temperature set points are changed by the seat occupants or if the outside air temperature changes, automatic seat levels will not be increased.


If the seats were turned off automatically and conditions change, the automatic function will not be turned back on.


An automatic activation can be overridden by an occupant at any time by pressing the seat heating or cooling button. In this case, the automatic operation is suspended until the next ignition cycle. The automatic function also can be activated or deactivated through the settings customization menu, which is a separate menu entry from the remote start settings.


The passenger seat will only be triggered for automatic operation if the seat is occupied.


Auto heated seat functions are not available for the rear seats.


– Thanks to David Antal

Sound from Steering when Driving over Bumps

There may be a rattle or clunk sound coming from the front of some 2015-2016 Colorado and Canyon models when driving over bumps. Upon inspection, this sound may be isolated to the lower steering intermediate shaft.


A redesigned intermediate shaft has been released to address this condition. Replace the lower steering intermediate shaft with new part number 84039333. Refer to the appropriate Service Information.


Before removing the steering intermediate shaft from the steering column (Fig. 18), the steering wheel must be secured in position before disconnecting the steering column, intermediate shaft and steering gear. Do not rotate the steering wheel or move the front tires or wheels. Any movement may cause possible damage to the SIR coil.


TIP: Prior to steering intermediate shaft reassembly, remove the plastic insert located at the bottom of the steering intermediate shaft.


F18 i-shaft

Fig. 18


– Thanks to Ken Cole

Service Know-How

10216.03D – Emerging Issues

March 10, 2016


To view Emerging Issues seminars:

• Log in to

–   Select Resources > Service Know-How/TECHAssist > Emerging Issues > Searchable Streaming Video; or

–   Select Catalog to search for the course number, and then select View > Take or Continue Course

Bulletin Review – February 2015

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The All-New 2016 Malibu

Completely redesigned from the ground up, the 2016 Malibu midsize sedan (VIN Z) boasts new styling, advanced safety technologies and a variety of connectivity features.


The new Malibu is available in L, LS, LT and Premier (Fig. 1) trim levels. A Hybrid model will be available later this spring.


F01 Malibu 1

Fig. 1


Although 300 pounds (136 kg) lighter than its predecessor, the Malibu’s wheelbase is four inches (102 mm) longer, creating more interior space. An important goal was to make the Malibu the most mass-efficient car in its class, with the mass savings spread throughout the vehicle. The increased use of aluminum in the vehicle, such as an aluminum hood that is 5.6 lbs. (2.5 kg) lighter than the current model’s aluminum hood and more aluminum chassis and suspension components, deliver weight savings. This provides a greater overall balance between a more responsive driving experience and efficient operation, resulting in increased fuel efficiency.


Turbocharged Engines


An all-new Ecotec 1.5L 4-cylinder turbocharged engine (RPO LFV) (Fig. 2) serves as the Malibu’s standard engine and is part of a new global family of small-displacement gas engines designed with greater power density to deliver performance and efficiency. It produces 160 horsepower and 184 lb.-ft. of torque and is mated to the Hydra-Matic 6T40 6-speed automatic transmission (RPO MNH).


F02 1.5 engine

Fig. 2


The available 2.0L 4-cylinder turbocharged engine (RPO LTG) (Fig. 3) offers a higher degree of performance while maintaining efficiency, generating 250 horsepower and 260 lb.-ft. of torque. This engine is paired with the Aisin AF50 8-speed automatic transmission (RPO MRC).


F03 2.0 engine

Fig. 3


TIP: Premium fuel is recommended with the 2.0L engine but not required. When towing, use only unleaded gasoline with an octane rating of 89 or higher. Using gasoline with a lower octane rating while towing may damage the engine.


Both engines feature a DOHC design with continuously variable valve timing, high-pressure direct injection, coil-on-plug ignition and electronic throttle control.


Along with fuel-saving Stop/Start technology that temporarily turns off the 1.5L engine when the Malibu comes to a stop, the vehicle employs active grille shutters that enhance aerodynamics when cooling and A/C loads are relatively low and high levels of front-end airflow are not required. If greater airflow is needed, the grille system opens one or both shutters. The actuators are powered by an ignition circuit that is active when the key is in the Run position. The vehicle may have to be driven for up to 13 minutes at speeds greater than 25 mph (40 km/h) before a shutter begins to move. If low ambient temperature is detected, the shutters will remain in the closed position.


TIP: Vehicles with active grille shutters cannot be dinghy towed.


Preview: Hybrid Engine/Drive Unit


The upcoming Malibu Hybrid will deliver an exceptional level of fuel efficiency — an estimated 47 mpg combined — with an all-new powertrain that uses technology from the 2016 Volt. A direct-injection 1.8L 4-cylinder engine is mated to a two-motor drive unit (slightly modified from the Volt unit) to power the Malibu Hybrid. (Fig. 4) The drive unit provides additional power to assist the engine during acceleration for 182 horsepower of total system power.

F04 1.8 unit

Fig. 4


The Malibu Hybrid’s engine also will feature Chevrolet’s first application of Exhaust Gas Heat Recovery (EGHR) technology, which uses exhaust heat to warm the engine and cabin. EGHR improves engine warm-up and ensures consistent fuel economy performance in cold weather.


An 80-cell, 1.5 kWh lithium-ion battery pack (Fig. 5) provides electric power to the hybrid system and can propel the Malibu Hybrid up to 55 miles per hour (89 km/h) on electricity alone. The gas-powered engine activates automatically at higher speeds and higher loads to provide more power.


The high voltage battery pack and drive unit will be on exchange when the model is introduced. Contact the Technical Assistance Center if any conditions are found with these systems.


F05 battery pack

Fig. 5


In addition to the drive unit, the Malibu Hybrid shares the Volt’s blended regenerative braking system, which provides maximum kinetic energy recovery during braking to help maintain the battery charge.




The Bosch ABS 9.0 brake system’s Electronic Brake Control Module (EBCM) and Brake Pressure Modulator Valve are serviced separately. The modulator valve employs a four-circuit configuration to control hydraulic pressure to each wheel independently. Vehicle performance enhancement systems include ABS, Electronic Stability Control (RPO FX3), Hill Start Assist and Traction Control.


Safety Technologies


The safety features on the all-new Malibu are many. These features assist drivers on the road as well as when parking the vehicle. The available safety technologies include:

• Rear Vision Camera

• Forward Collision Alert with Following Distance Indicator

• Intelligent Brake Assist

• Forward Automatic Braking

• Front Pedestrian Braking

• Lane Keep Assist with Lane Departure Warning

• Lane Change Alert with Side Blind Zone Alert

• Automatic Parking Assist

• Front and Rear Parking Assist

• Rear Cross Traffic Alert

• Adaptive Cruise Control

• IntelliBeam Headlamps

• Hill Start Assist



Chevrolet MyLink and Infotainment Options


The Chevrolet MyLink system is now standard on the LS, LT and Premier trims. The Malibu offers four different infotainment options with availability based on model and packages. (Fig. 6)


F06 Malibu 2

Fig. 6


New connectivity features that are available include:

• OnStar 4G LTE with built-in Wi-Fi

• Wireless phone charging

• Chevrolet MyLink with Android Auto and Apple CarPlay compatibility

• Teen Driver, which allows parents to view their kids’ driving statistics, such as maximum speed, warning alerts and more



The all-new Teen Driver feature — available with the 8-inch MyLink radio — allows parents to restrict certain vehicle functions, such as radio volume, to support safer driving. The system is activated based on the key used and gathers driving statistics, such as maximum speed, warning alerts, distance driven, overspeed warnings, Forward Collision Alerts, Forward Collision Avoidance Braking and Stability Control activations, viewable via a Report Card. (Fig. 7)


F07 Malibu 3

Fig. 7


When the vehicle is started with a registered key, the Driver Information Center (DIC) displays a message that Teen Driver is active.


Special Tools


The Aisin AF50-8 transmission special tools will be shipped to dealers in June 2016 after the warranty exchange period.


Chevrolet dealerships received special tools earlier this year for the Spark and Volt that are applicable to the 1.5L turbocharged engine (RPO LFV).


For additional information on the all-new 2016 Malibu, refer to Bulletin #15-NA-085.


– Thanks to Dallas Walton and Sherman Dixon



New GM Accessories Information Center Website

The new GM Accessories Information Center gives technicians easy access to all the details on a variety of vehicle accessories — from ambient lighting to wheel lock kits — all in one place.


The new website, (Fig. 8), is available through GM GlobalConnect and enables users to look for all accessories by division, model, year and trim level, or to search by part number. If you’re not sure about the applications of a particular accessory, the Accessories Information Center is a good place to start.


F08 aic 1

Fig. 8


Search Results


Searching by model will provide a list of available accessories, including interior, exterior, performance, security and wheel accessories.


The part search information results provide the current part status, marketing information, engineering information and the model applications. For example, searching for part number 92248560 shows that the ground effects package applies to several 2010-2013 Camaro models. (Fig. 9)


F09 aic 2

Fig. 9


Catalogs and Marketing Materials


Divisional and model accessory materials and information are readily obtainable by clicking the Accessories Reference Catalogs link on the home page. It includes associated accessory information, marketing materials, model launch kits and reference catalogs for most 2014 and later GM cars and trucks.


Training Assistance


Training videos and PDFs covering installation procedures also can be downloaded from the website by clicking the Tools menu and selecting Training. The available information can help with the installation of various accessory items, such as ground effects and ladder racks.


Customize Your Experience


Just like the customization that GM accessories provide, the website also can be customized by each user, so the home page features the topics that mean the most to you, such as Training or Accessories Search.


Click the Customize Homepage link at the bottom of the home page to display a menu of website modules. The selected modules will appear across the bottom of the home page.


– Thanks to Matt Singer and Mike Magyar




System Software Makes Accessory Installation Easier

The installation of some Limited Production Option (LPO) accessories is now made easier at the dealership thanks to the system software being installed in the vehicle during production.


The GM Accessories Remote Start kit for the 2016 Malibu (VIN Z), for example, does not require any programming if the vehicle was ordered with the kit (RPO S6P).


If the vehicle was built with RPO S6P, it was produced with the correct system software so a call to the Techline Customer Support Center (TCSC) for a calibration is not required. Completing installation of the remote start kit only involves learning the new transmitters (key fobs) to the vehicle. Refer to the accessory installation instructions in the appropriate Service Information for more information.


TIP: Before installation, verify the vehicle has the correct software by checking the VIN and the required RPOs in the Investigate Vehicle History system.


Look for other models in the future to also have the system software installed for LPO accessories. The Sport Light Bar Kit for 2016 full-size trucks is another example.


With this new built-in functionality, it’s recommended to always check the IVH system before installing accessories or calling TCSC.


– Thanks to Matt Singer and Dallas Walton


Using GM-Approved Battery Chargers and Booster Packs

Occasionally, a vehicle in for service or in dealership inventory may require a jump start for a dead battery. One case at a GM dealership recently illustrated the importance of proper battery maintenance and using GM-approved battery chargers or booster packs.


Several vehicles returned to the dealership with both low-beam headlamps burned out. The cars had low mileage, but had been recently jump started after being in dealership inventory for several months. It was found that the non-approved booster pack used to jump start the cars was exceeding 20 volts at the headlamps, which caused the bulbs to be stressed during the jump start. Typically, the bulbs failed a few drive cycles later.


GM testing confirmed the condition using the same booster pack, showing the high voltage spike as the cause of the burned out headlamps.


The use of non-approved battery chargers and boosters can also damage control modules and other electrical components. This damage is not covered by the new vehicle warranty. Warranty claims for component damage caused by non-approved equipment at the dealership may be debited.


TIP: The battery charger has to allow for an AGM selection when charging an Absorbent Glass Mat battery; otherwise, there is a risk of damaging the AGM battery.


These conditions also may be seen when a vehicle is brought in for service after a roadside assistance event. It’s recommended to communicate to local roadside service companies the importance of using the proper battery jump starters.


Maintaining Batteries


For information on maintaining vehicle batteries in dealership inventory and the proper use of equipment during jump-starting procedures, refer to Bulletin #09-00-89-002: Properly Maintaining Vehicles in Dealer Inventory and Bulletin #15-06-03-001: Cold Weather and Long Stand Time Battery Maintenance and Testing Tips.


Battery Chargers


The EL-50313 Midtronics GR8 is an essential tool shipped to all dealerships for warranty repairs. It creates a printout that can be attached to the repair order.


There are several other battery chargers/testers that are GM-approved and offered through GM Dealer Equipment. Convenient devices to use outside the service garage are new GM-approved micro jump starters. These portable jump starters are small enough to fit in a pocket or tool box and feature a 12V lithium-polymer power supply to start an engine as well as charge electronic devices, such as a phone or tablet.


For more information, go to


In Canada, go to the Dealer Equipment & Services (DES) Canada website at


Examples of GM-Approved Battery Chargers (Fig. 10)


F10 battery chargers

Fig. 10



Examples of GM-Approved Jump Starters/Chargers (Fig 11)


F11 battery boosters

Fig. 11


– Thanks to Jon Nowak


Transmission Adaptive Functions

Some owners of low-mileage 2015-2016 Cadillac, Chevrolet and GMC models equipped with the new 8L90 or 8L45 automatic transmission (RPOs M5U, M5T, M5N, M5X) may comment that shifting feels too firm (harsh) or that it slips or flares.


These transmissions use an adaptive function that’s designed to keep the transmission clutch apply time(s) at the predetermined length to produce the intended shift feel. This results in the transmission automatically adapting the clutch apply pressure(s) over time.


The purpose of the adaptive function is to maintain the time it takes to complete a clutch apply to produce the desired shift quality for the various vehicle shift control systems. The adaptive function is a continuous process that will help maintain optimal shift quality throughout the life of the vehicle.


How the Adaptive Function Operates


The Hydra-Matic 8-speed transmission (Fig. 12) employs a line pressure and volume control system during upshifts to compensate for new transmission build variation as well as the normal wear of components. Over time, the variation from new and normal wear of the apply components within the transmission can cause shift time (the time required to apply a clutch) to be longer or shorter than desired.


F12 8speed trans

Fig. 12


To compensate for these changes, the Transmission Control Module (TCM) adjusts the pressure commands to the various pressure control (PC) solenoids to maintain the originally calibrated shift timing. The automatic adjusting process is referred to as adaptive learning and helps ensure consistent shift feel while increasing transmission durability.


The TCM monitors the A/T input speed sensor (ISS) and A/T output speed sensor (OSS) during commanded shifts to determine whether a shift is occurring too fast (harsh) or too slow (soft). It then adjusts the corresponding PC solenoid signal to maintain the set shift feel.


Adjusting Adapts for Correct Shift Feel


The transmission adapts can be reset and relearned on most vehicles. Clearing and relearning the shift adapts should not be considered a repair process and is intended to be performed only when a repair has been performed to the transmission.


If a transmission assembly, valve body or Transmission Control Module (TCM) replacement is required, reset the shift adapts by performing a refresh of the Characterization Data and completing the Transmission Service Fast Learn procedure. These procedures are completed in the service bay using GDS 2. After performing the procedures, evaluate the shifts and further learn pressures and volumes if required.


If there is a specific shift concern on the transmission, the Service Fast Learn should not be performed. Complete the appropriate driving learn procedure to further learn clutch pressures and volumes for specific shift concerns.


For details on these adaptive learn procedures, refer to Bulletin #16-NA-019 for MY 2016 and Bulletin #14-07-30-001F for MY 2015. These procedures are model year specific.


– Thanks to Mark Gordon



Poor Heater Performance

Some 2015-2016 Colorado and Canyon models may have poor heater performance with the HVAC system only blowing cold air. Relearning the HVAC doors may temporarily eliminate this condition.


Remove the temperature actuator and inspect for a cracked or broken shaft on the temperature valve. (Fig. 13) If the shaft is cracked in only one place, install a #4 hose clamp over the temperature valve shaft. (Fig. 14) It is not necessary to remove the door to add the clamp.


F13 shaft 1

Fig. 13


F14 shaft clamp

Fig. 14


If the shaft is cracked in more than one place or it is broken and has more than one piece missing, the temperature valve must be replaced.


– Thanks to Ken Cole

Battery Discharged Overnight

The battery may discharge overnight on some 2015-2016 Colorado and Canyon models. It may be possible to duplicate a 150 mA or 450 mA draw.


If this condition is found, inspect connector X301 (Headliner to Body Harness) near the Center High-Mounted Stop Lamp (CHMSL) for bent pins. (Fig. 15) Repair or replace the terminals as needed.


F15 bent pins

Fig. 15


– Thanks to Ken Cole

Rear Auxiliary Heater Lines Rattle

There may be a rattle or buzz sound from the rear of the vehicle on some 2015-2016 Tahoe, Suburban, Yukon models and Escalade models. The sound may be due to the rear auxiliary heater/evaporator lines (Fig. 16) contacting each other and may be most noticeable while driving at 35 to 40 mph (56 to 64 km/h) or in gear at a stop.


F16 line 1

Fig. 16


Road test the vehicle to achieve operating temperature. Remove the right rear inner fender well and inspect the rear auxiliary heater/evaporator lines for contact.


If the lines are contacting each other (Fig. 17), loosen the retaining clamps and reposition the lines to gain more clearance. Retighten the retaining clamps.


F17 line 2

Fig. 17


– Thanks to Jim Will

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  • [+]2016
  • [+]2015
  • [+]2014