Archive for August 2015

Keep the Field Product Reports Coming

Dealership employees play a key role in reporting product issues using the Field Product Reporting process (in Canada, referred to as the Product Information Reporting process). The timeliness and detailed information in these reports are extremely important to the product problem resolution process.


Field Product Reports can be helpful in communicating a number of conditions, such as wiring harness routing damage (submitted with photos), emerging repetitive repairs not addressed by a Bulletin or PI, or significant issues not covered under warranty (including conditions considered normal operation or found during PDI).


Why are Field Product Reports Needed?


Field Product Reports provide:

• Early identification of emerging issues (starting point)

• Provide direct feedback to GM Engineering on customer concerns

• Provide real-world examples to GM Engineering

• Allow GM Engineering to review concern and repair information directly from the dealership/service technician

• Provide feedback to GM plants on potential build issues


The details in the Field Product Reports provided by first-hand observations from technicians help to collectively identify and address all types of emerging issues, including safety concerns, affecting new vehicles. This information is especially critical during the launch of new models.

When considering if submitting a product report is necessary, determine if it meets the following three critical points:


Critical Product Concern – Safety concern, no start, walk-home condition (including vehicles towed to dealerships or involving leaking fluids)


Critical Timing – Safety concern, vehicle in dealership, plant build concern


Critical Information – More details, including photos or videos to better understand a condition


TIP: Service Information, Bulletin information and Labor Time Guide issues should be addressed through Service Information Feedback, not a Field Product Report.


Submitting a Field Product Report only takes a few minutes. Information in the report should include:


Required information section:

• VIN (last 8 lookup or full VIN)

• Odometer

• Condition

• Cause

• Correction


More Information expanded section:

• Job Card #

• TAC Case #

• Part # (numbers – provide scan)

• Photo (max number = 6)

• Video (max duration = 30 Seconds)


Download the App to Make Submitting Field Product Reports Easier


The Field Product Report application (U.S. dealerships only) makes it easy to create and submit a report. The GM Field Product Reporter app is free and can be found on the app stores for Android and Apple devices. (Fig. 1)


F01 report app 1

Fig. 1


To use the app, download it to your mobile device and log in using your GlobalConnect ID and password (user profile information must be filled out on the initial use), and then start filling out the required fields. (Fig. 2) You can also attach up to six photos or up to 30 seconds of video, including audio.


F02 fpr app example

Fig. 2


After sending a report, all photos and videos will be deleted from the device. To save a copy of the report or send it to additional addresses, add the addresses in the “TO:” line on the top of the review screen.


Email a Report


In addition to the Field Product Report app, reports can still be submitted via email in the U.S. Fill out the form located on GM GlobalConnect > Service Workbench > Service Forms and email it to


In Canada, reports can be submitted online via the PIR Online app located in the Service Department page of GM GlobalConnect.


For more information about when and how to submit a Field Product Report, refer to Bulletin #02-00-89-002O (U.S.) or Bulletin #10-00-89-006 (Canada).


– Thanks to Ray Romeo

Automatic Java Updates and GM Service Applications

TIS2Web uses the Java program to launch GM Service Applications such as SPS, GDS2 and MDI Manager. Java acts as a “plug-in” that assists the programming code with executing functions. Since Java is a program itself that is owned and managed by the company Oracle, updates to the Java program sent out by Oracle can affect the functionality of the GM Service Applications.


Currently, the supported version of Java for the GM Service Applications is Java 7 Update 67. It’s best to have only this version of Java installed. When Java updates, it leaves old versions on the machine that build up over time, which can eventually cause issues.


Java is generally updated every three months. The default setting in the Java Control Panel is set to “Automatically Update”. This can be problematic if you wish to stay on one version of Java that is stable and compatible with your applications. The Java settings can be changed to disable the automatic updates.


Disabling Automatic Updates for Java


Open the Windows start menu and click Control Panel.


With the control panel in icon view (view by large icons or small icons), click the icon that says Java to open the Java control panel. (Fig. 3)


F03 java 1

Fig. 3


Click the Update tab. Remove the check in the box next to “Check for Updates Automatically.” (Fig. 4)


F04 java 2

Fig. 4


A pop-up window will display once the box for automatic updates has been deselected. Click the “Do Not Check” button in the pop-up window. (Fig. 5)


F05 java 3

Fig. 5


Click the “OK” button and the change to disable automatic updates of Java will be saved.


– Thanks to Chris Henley

Transmission Downshifts during Normal Mode Powertrain Grade Braking

F06 15canyon

Fig 6


Powertrain Grade Braking is a transmission feature on 2013-2015 Avalanche, Silverado, Suburban, Tahoe, Express, Savana, Sierra, Yukon models and Escalade models equipped with the 6L80 (RPO MYC) or 6L90 (RPO MYD) automatic transmission and 2015 Colorado and Canyon models equipped with the 6L50 (RPO MYB) automatic transmission that helps to maintain the desired speed when driving on a downhill grade. The system uses the engine and transmission to slow the vehicle by maintaining lower gears longer and increasing shift pressures. This helps reduce brake temperatures and wear on the braking system, saves fuel, and provides enhanced vehicle control.


Because the transmission may downshift unexpectedly when Powertrain Grade Braking is active, some owners may have concerns about how the transmission operates.


Starting with the 2013 model year, full-size trucks and utilities have had Powertrain Grade Braking while the transmission is in Normal mode is when Tow/Haul mode off. Powertrain Grade Braking has been available since 2009 on light-duty models and 2007 on heavy-duty models, but the Tow/Haul mode had to be selected. Powertrain Grade Braking should not be confused with Cruise Grade Braking.


Powertrain Grade Braking Operation


Normal Mode Powertrain Grade Braking defaults to ON at each ignition key cycle. To disable/enable all grade braking, press and hold the Tow/Haul button on the shift lever for three seconds.


No grade braking is available in Range Selection Mode (Manual Shift Mode).


Powertrain Grade Braking requires the driver to apply steady brake pedal pressure to maintain the desired speed while driving on a downhill grade. The vehicle’s control modules monitor the amount of brake pedal apply, vehicle deceleration rates, and other factors to determine if Normal Mode Powertrain Grade Braking is necessary. When the feature activates, the transmission downshifts and engine RPM increases. At this point, if the brake pedal is released, the transmission will hold the current gear. If the driver reapplies steady brake pedal pressure and additional engine/transmission braking is needed to help maintain the desired speed, additional downshifts may occur. Grade braking is exited the accelerator pedal is depressed.


Normal Mode Powertrain Grade Braking has a less aggressive transmission downshift schedule than when in Tow/Haul mode.


Driver Information Center Messages


There are several messages that will display in the Driver Information Center depending on the state of the Powertrain Grade Brake system.


GRADE BRAKING DISABLED or GRADE BRAKING OFF displays when the system has been disabled with the Tow/Haul button.


GRADE BRAKING ENABLED or GRADE BRAKING ON displays when the system has been enabled with the Tow/Haul button.


GRADE BRAKING ON or GRADE BRAKING ACTIVE displays when the system activates for the first time in an ignition cycle while driving on a downhill grade. (Fig. 7) This message only appears the first time the system is activated and does not appear later when the system is activated again when driving on roads with many changing grades.


F07 grade braking on

Fig. 7


Hill Descent Control


Normal Mode Powertrain Grade Braking is not the same system as Hill Descent Control (HDC), which uses the braking system maintain vehicle speed on a very steep incline greater than or equal to a 10 percent grade. The HDC system must be turned on or off using the switch on the center stack. To enable HDC, vehicle speed must be below 37 mph (60 km/h). A blinking HDC light indicates that the system is actively applying the brakes to maintain vehicle speed. The system is automatically disabled if vehicle speed is above 50 mph (80 km/h) or above 37 mph (60 km/h) for at least 30 seconds.


– Thanks to Nick Champion

Aftermarket Navigation Systems

Many aftermarket companies advertise modules that are designed to upgrade a non-navigation infotainment system to a navigation-enabled system on vehicles equipped with Chevrolet MyLink, GMC or Buick IntelliLink (Fig. 8) or Cadillac CUE infotainment systems. In many cases, the aftermarket module replaces the OEM Human Machine Interface (HMI) module.


F08 nav system

Fig. 8


The aftermarket modules are marketed as a replacement HMI module that contains the navigation software necessary to run the navigation system. The modules replace the existing HMI module and use the factory wiring harness and bolt locations. These components are not supported by GM in any way and are not approved as an accessory that is compatible with any GM infotainment system.


If an aftermarket HMI module is installed, it can cause various other issues that affect the proper operation of several systems. For example, the aftermarket module may cause the Rear Vision Camera to not work properly. Or if a technician attempts to reprogram an aftermarket module, it may not accept the programming and fail, causing irreparable damaged to the module, because it’s not the correct HMI module for the vehicle calibration.


Verify the Part Number


If it’s suspected that an aftermarket module it installed in a vehicle, verify the part number with the correct part number for the appropriate model year in the electronic parts catalog.


– Thanks to Mike Magyar

Obtaining a TAC or PQC Case

GM dealership service managers who would like a copy of a GM Technical Assistance Center (TAC) or Product Quality Center (PQC) case covering an issue at their dealership, can now request one through a new process at TAC. The formal process enhances the support being provided to dealerships by TAC.


Dealership service management can request a TAC or PQC case in PDF format. To request a copy of a case:


• Send the formal request via e-mail from a GM dealership (non-personal) e-mail account to your District Manager of Aftersales (DMA) and copy GM TAC at

• Write “TAC/PQC Case Request – DMA Approval Required” in the e-mail Subject line.

• Include the dealership’s BAC, the VIN, TAC/PQC case number as well as your name, dealership position, and contact number at the dealership in the e-mail message.

• If the DMA determines there is a true internal GM dealership business need for this request (i.e., case copy not to be provided to non-dealership personnel), the DMA will need to respond to GM TAC and the GM dealership with their approval before GM TAC will provide a copy of the TAC or PQC case.

• Once approved, an email with a PDF of the case will be sent to the requesting GM dealership.


Dealership service management in Canada can follow the same steps as detailed above. E-mail your District Manager – Customer Care and Service Process (DM-CCSP) and copy GM Canada TAC at


– Thanks to Cary Vernier


Low Air Conditioning Refrigerant Charge

Some 2013-2016 Traverse, Enclave, and Acadia models may have warm air conditioning. A check of the refrigerant level may reveal a very low/empty charge. After performing normal diagnostics, if the source of the refrigerant leak is not found, check for a small refrigerant leak at the rear auxiliary air conditioning evaporator.


Engineering has determined that dust from the blower motor brush on the evaporator may have some copper particles in it, which causes accelerated corrosion to the evaporator. The copper particles are coming from the blower motor during the motor break-in period, so the motor does not need to be replaced.


Remove the rear auxiliary blower control module and insert the GE 50078 Electronic Leak Detector to test for a leak. If a leak is found, replace the rear evaporator.


Also remove the rear blower motor and blow the fan and blower cage (Fig. 9) with compressed air to remove any copper particles and dust that could be redeposited on the new evaporator. This will prevent the possibility of a subsequent failure of the evaporator from the copper dust remaining on the blower fan cage.


F09 blower motor

Fig. 9


– Thanks to Jim Miller

Disconnected RCDLR Antenna Conditions

Some 2015 Escalade models, Suburban, Tahoe, and Yukon models may have DTCs for any of the tire sensors — C0750 (Left Front Tire Pressure Sensor), C0755 (Right Front Tire Pressure Sensor), C0760 (Left Rear Tire Pressure Sensor), and/or C0765 (Right Rear Tire Pressure Sensor) — set in the BCM. Other conditions may include:

• One or more tire pressures displaying dashes on the Driver Information Center (DIC)

• Service Tire Monitor System message displayed

• Poor range or an inoperative Remote Keyless Entry (RKE) transmitter

• No Fob Detected message displayed or inoperative passive entry system (if equipped)



These conditions may be caused by a poor or disconnected antenna connection. The Remote Control Door Lock Receiver (RCDLR) antenna system consists of the four components: RCDLR, coax cable, Antenna Amplifier Module, and an antenna (located in right rear quarter glass).


Before any components are replaced for these conditions, check for any disconnections in the RCDLR antenna system. There are three locations where the RCDLR antenna system can become disconnected:

1. Antenna Amplifier Module (Fig.10, #3) disconnected from the antenna at the right rear quarter glass (Fig. 10, #4)

2. Coax cable (Fig. 10, #2) disconnected at the Antenna Amplifier Module (Fig. 10 #3)

3. Coax cable (Fig. 10, #2) disconnected at the RCDLR (Fig. 10, #1)



F10 4233435

Fig. 10


The closer the disconnection is to the RCDLR, the greater the number of symptoms that will be noticed.


Here are several examples.


If the Antenna Amplifier Module is disconnected from the antenna at right rear quarter glass, there may be little to no noticeable issues, but the RKE range may be a little shorter than a similar vehicle.


If the coax cable is disconnected at the Antenna Amplifier Module, the RCDLR may have intermittent issues receiving signals from the Tire Pressure Monitor (TPM) sensors that are farthest from the RCDLR (LF, LR, RF tires). The DIC may display a Service Tire Monitor System message and dashes for these tire pressures. In most cases, the signal from the right rear tire sensor, which is the closest to the RCDLR, will not have any issues. The RKE will have a shorter range.


If the coax cable is disconnected at the RCDLR, the RCDLR may not receive any TPM sensor signals. The Service Tire Monitor System message and the tire pressures will show dashes in the DIC. The RKE system may work when the transmitter is inside the truck or just outside the truck. There may be Passive Entry/Passive Start conditions such as a No Fob Detected message or Passive Entry being inoperative. If the transmitter is placed into the transmitter pocket, the vehicle will start.


– Thanks to Jim Will


Trailer Brake Control Switch Wiring

An intermittent Service Trailer Brake message may be displayed on the Driver Information Center of some 2014 Silverado 1500 and Sierra 1500 models and 2015 Silverado and Sierra models. DTCs C1115 (Manual Trailer Brake Apply Request Switch Signal), C1116 (Manual Trailer Brake Apply Request Signal 1), C1117 (Manual Trailer Brake Apply Request Signal 2) and/or C1118 (Trailer Brake Control Sensitivity Switch Circuit) may be set in the Chassis Control Module.


The trailer brake control system has a control panel with trailer gain and manual apply switches. (Fig. 11) The control panel switches allow the driver to adjust the amount of output, referred to as trailer gain, available to the electric trailer brakes and to manually apply the trailer brakes.


F11 trailer brake control panel

Fig. 11


Use GDS to view the following Trailer Brake Control Switch parameters in the Chassis Control Module:

• Manual Trailer Brake Apply Request Signal 1 • Manual Trailer Brake Apply Request Signal 2 • Trailer Brake User Gain Switch


The normal working ranges for the Trailer Brake Control Switch parameters are:


Manual Apply Slide Lever Fully Applied

Signal 1 – 89% (+/- 5%)

Signal 2 – 11% (+/- 5%)


Manual Apply Slide Lever Fully Released

Signal 1 – 11% (+/- 5%)

Signal 2 – 89% (+/- 5%)


User Gain Switch

Switch at rest – 89% (+/- 5%)

+ switch pressed – 37% (+/- 5%)

– switch pressed – 23% (+/- 5%)


In most cases, the Chassis Control Module is not the cause of the DTCs and there is either a concern with the wiring to the trailer brake control switch or the switch itself.


The wiring between the Chassis Control Module and trailer brake control switch passes through in-line connector X185 or X138 (depending on  vehicle build; refer to the Service Information), as well as the X1 and X5 connectors of the X61A Junction Block-I/P. (Fig. 12)


F12 trailer brake wiring

Fig. 12


Inspect the wiring from the Chassis Control Module to the trailer brake control switch. Check the connectors for any backed out, loose, or poor tension terminal/connector issues.


If no wiring issues are found, check the trailer brake control switch. The trailer brake control switch parameters can be monitored with GDS while wiggling the circuits/harness between the Chassis Control Module and switch. Look for the values to change.


– Thanks to Jim Will

New AFIT Tool Adapters Coming This Fall

Several new control modules on 2016 GM models use new sensor technology. The SAE J2716 SENT (Single Edge Nibble Transmission) protocol allows for high resolution data transmission from a sensor to a control module, such as readings for temperature, pressure, throttle position and mass airflow.


The SENT protocol is a one-way asynchronous voltage interface that requires three wires — a signal line, supply voltage line and ground line. An asynchronous signal uses a form of computer control timing protocol in which a specific operation begins upon receipt of an indication (signal) that the preceding operation has been completed. A transmitted signal consists of a series of pulses, where the distance between consecutive falling edges defines the transmitted 4-bit data nibble.


This new technology requires three new adapters for the CH-47976-500A Active Fuel Injector Tester (AFIT) for the 2016 model year.

Screen Shot 2015-08-07 at 4.43.07 PM

Alternative Diagnostics


The new tool adapters for the 2016 ATS, CTS, XTS and Encore will not be available at the start of production. Instead of using the AFIT, the diagnostic procedures included in the appropriate 2016 Service Information should be used.


If dealerships need additional help with the existing tools and procedures, Bosch can offer assistance and provide a loaner tool for temporary use. Call 1-800-GM-TOOLS (1-800-468-6657) and select for prompt 3 for Special Service Tools.


The new adapters are expected to be shipped to dealerships in September 2015.


– Thanks to Jon Nowak



Updated Dealership Guidelines for Computers in the Service and Parts Departments

The GM Dealership Infrastructure Guidelines (version 15.2) have been updated recently with the hardware and software specifications required for GM dealerships to follow when purchasing new computers for use in the service and parts departments.


The most notable change in the guidelines is the recommendation to use Internet Explorer (IE) 11. IE 10 is the minimum browser version. PCs running IE 9 are encouraged to update to IE 11.


The updated guidelines provide a detailed description of what is and what is not currently supported by GM to properly run Techline software (TIS2Web, SPS, GDS2, MDI, Tech2Win, and Service Information).


GM continues to support:

• Intel i3/i5/i7 processors

• Business grade hardware (PC and Access Points)

• Windows® 7 Professional 32 bit and 64 bit operating systems

• Windows Vista Business 32 bit SP1.

• Internet Explorer (IE) 11


GM does not support the following:

• All processors below the Intel I series plus AMD, Celeron and Atom processors

• Consumer grade hardware

• Non-branded, built by hand or think client PCs

• Tablets running Android or Mac operating systems

• Windows XP or XP Mode/Virtual PC

• Any Home version of operating system

• Windows 8.x (any version)

• Java 64 bit version

• Internet Explorer 64 bit version

• Apple or Mac tablets, PCs




TIP: Computers purchased preinstalled with Windows 8.1 Pro software may include downgrade rights to Windows 7 Professional. Contact your PC manufacturer or refer to Microsoft’s website for further details regarding eligibility and options available. Do not update to the new Windows 10 operating system until General Motors communicates applications are compatible.


Techline requires local Windows administrative access for software installation and updates. The guidelines include an updated list of Techline security and firewall exceptions for TIS2Web applications. This information should be communicated to your dealership IT specialist to reference as recommended firewall exceptions.


The complete Dealer Infrastructure Guidelines are available at under the Techline IT Solutions tab > GM IT Standards. In Canada, the Dealer IT Guidelines are located in the GlobalConnect Reference Library under Service.


Any questions regarding the guidelines or where to purchase PC hardware should be directed to the Techline Customer Support Center (TCSC) at 1-800-828-6860 (English) or 1-800-503-322 (French).


– Thanks to Lisa Scott

Rear Leaf Spring Noises

A squeaking or clunking noise may be heard coming from the rear of some 2015 Colorado and Canyon models as well as late model full-size trucks. These noises have been traced to the rear suspension leaf spring area.


Do not replace the rear leaf springs for a noise condition.


A squeak noise from the rear leaf springs on 2015 Colorado and Canyon; 2007-2015 Silverado and Sierra; 2007-2012 Colorado and Canyon; 2007-2010 Hummer H3 and H3T; and 1999-2007 Silverado (Classic) and Sierra (Classic) may be due to debris getting between the leaf springs. The frequency and severity of the noise is affected by the types of local roads on which the vehicle is driven.


Pressure wash the rear leaf springs to remove as much dirt and debris as possible. Dry the springs with compressed air. Apply a liberal amount of grease (P/N 12345996, U.S.; P/N 10953501, Canada) both underneath and on top of the front and rear plastic pad inserts for the #2 and #3 leaves. (Fig. 1) Protect any tool used to gently pry up the tip inserts to prevent damage to the spring leaves. Refer to Bulletin #06-03-09-004G for more details.


F01 rear leaf spring patch

Fig. 1


Clunking noises on 2015 Colorado and Canyon; 2014-2015 Silverado 1500, Silverado 2500/3500, Sierra 1500, Sierra 2500/3500; and 2007-2013 Silverado and Sierra models can usually be eliminated by re-torqueing the joints of the leaf spring assembly. This includes the shackle joint to the frame and to the rear eye (Fig. 2, #1), the anchor plate U-bolts (Fig. 2, #2), and the front rear-spring mounting nut. (Fig. 2, #3) Refer to the appropriate Service Information for the correct torque specifications. Refer to Bulletin #09-03-09-001C for additional information.


TIP: It is not necessary to remove the fuel tank to re-torque the leaf spring.


F02 rear leaf spring assembly



– Thanks to Charles Hensley

Low Oil Pressure on V8 Engines

A Service Engine Soon (SES) lamp may be illuminated or low oil pressure may be indicated on the instrument cluster with DTC P0521 (Engine Oil Pressure Sensor Performance) stored on some 2007-2013 CTS-V, Escalade, Avalanche, Camaro SS, Colorado, Corvette, Express, Silverado, Suburban, Tahoe, Canyon, Sierra, Savana, and Yukon models equipped with a V8 engine (RPOs L20, L77, L94, L96, L99, L9H, LC8, LC9, LH9, LMF, LMG, LY6, LZ1). In some cases, these conditions may have started shortly after an oil change.


If DTC P0521 and/or low oil pressure is indicated on the instrument cluster in cold or hot weather on a Gen4 V8 engine and the engine is currently equipped with a PF48E oil filter, determine if the engine has been properly repaired and cleaned following the procedure used in the latest version of Bulletin #10-06-01-008. The bulletin covers engine oil consumption on engines with Active Fuel Management (AFM). If the engine has not been properly repaired, update the engine with the components outlined in the bulletin.


If the engine has been properly repaired and cleaned, inspect the left rocker cover (square baffle) (Fig. 3, #1 – old design; #2 – new design with square baffle) and verify that the baffles can hold water and do not leak. If any leaks are found, clean and seal the edge of the baffle with RTV, if possible, or replace the valve cover. Thoroughly clean and dry the valve cover before installation and/or resealing.


In addition, change the engine oil and replace the oil filter with a PF48E filter.


F03 new baffle

Fig. 3


– Thanks to Rich Renshaw and Tracy Lucas

Track Engine Temperature on Track-Ready Corvettes

There may be some questions from owners of track-ready 2015-2016 Corvette Z06 models (equipped with the 6.2L engine – RPO LT4) regarding the hot temperature message. Here’s some information to relay to owners about Corvette track-ready vehicles and track engine temperature.

2016 Chevrolet Corvette Z06

 Fig 4

The manual transmission-equipped Z06 is designed to keep engine oil, coolant, transmission and differential fluids below the hot warning targets when driven by a professional driver on an 86°F (30°C) day on a “typical” racetrack for an indefinite period of time (effectively the time to burn through a full tank of fuel). The Corvette team validates the durability of the Z06 cooling systems with a 24 hour accumulated track test to simulate the most aggressive track day usage by Corvette owners.


The Milford Road Course at the GM Proving Ground used by the Corvette team is designated as a “typical” standard track, but GM recognizes that there are tracks around the world that are easier on a cooling system and some that are harder on a cooling system. Generally speaking, tighter tracks with a lower average speed and higher sustained RPM will drive higher fluid system temperatures. In addition, higher ambient temperature conditions affect any car’s ability to run sustained laps at ten-tenths.


On Z06 models equipped with an automatic transmission, when in the Drive (D) position, the transmission selects the lowest possible gear ratio for the best acceleration and, because it has eight closely-spaced ratios, typically runs a higher average RPM than vehicles with the manual transmission. This optimizes lap time performance, but also taxes the engine oil and coolant more for any given track. As a result, the automatic transmission has the capability to run faster laps than the manual transmission, but thermal limitations are reached more quickly. Owners who are planning to run extended track-day sessions at “professional” speeds are advised to use a vehicle equipped with the manual transmission, or to paddle shift the automatic transmission and select higher gears when conditions warrant.


Any time the maximum recommended temperatures are reached in any condition, warnings will display on the Driver Information Center at the appropriate time for coolant, oil, or transmission fluid. A cool-down lap or two will bring operating temperatures back to a reasonable level and then aggressive track driving can be resumed.


Some may wonder why the Corvette is not designed to higher temperatures, say 110°F (43°C), to accommodate southern tracks in the summer. Corvettes have been designed using the “pro driver at 86 degrees” criteria for generations and, for the vast majority of owner use, it has resulted in excellent performance. If the Corvette was designed to higher temperature criteria, it would require adding additional cooling hardware, which drives up mass and, perhaps more importantly, requires the system to be fed more air. This would have a great impact on appearance and aerodynamic drag. Like most aspects of car design, the challenge is in finding the best balance of conflicting requirements.


– Thanks to Tracy Lucas

Door Striker Cover Installation during PDI

Installation of the front and rear door striker covers is part of the Pre-Delivery Inspection (PDI) process for 2015-2016 Escalade models; 2015-2016 Tahoe LTZ, Suburban LTZ and Yukon Denali models. These covers are shipped with the vehicle from the assembly plant.


When installing the door striker, check its orientation to ensure it is not installed backwards. The rounded side of the cover should be positioned toward the outboard side of the vehicle during installation. (Fig. 5)


F05 3723507

Fig. 5


– Thanks to Jim Will

Instrument Panel Rattle Sounds

There are three areas that have been identified that may cause a rattle-type sound from the instrument panel area on some 2015 Escalade models, Silverado, Suburban, Tahoe, Sierra, Yukon; 2014 Silverado 1500 and Sierra 1500 models equipped with the 110 Volt AC Converter (RPO KI4).


Condition 1: A metallic rattle-type sound from the left side of the instrument panel area.


The sound may be caused by the K14 110 volt power inverter module (Fig. 6) not being seated properly in the mounting bracket. Inspect the accessory AC and DC power control module located to the right of the steering column for possible movement against the mounting bracket. (Fig. 7)


F06 4215620.jpg inv2

Fig. 6


F07 4215623.jpg inv3

Fig. 7


Also remove the K14 power inverter module and apply Kent Automotive two-sided tape (P/N P40519) or equivalent to the module bracket to insulate it from the mount. (Fig. 8)


F08 4215617.jpg inv1

Fig. 8


Condition 2: A rattle or itch-type sound from the center of the instrument panel in the radio area.


The instrument panel accessory bezel may be rattling due to insufficient tension of the retainers. Press on the bezel while duplicating the sound to see if it is eliminated. Wrap Kent Automotive BRS flocking tape (P/N KT13487) or equivalent over the ten retainers and reinstall the bezel. (Fig. 9)


F09 4224095

Fig. 9


Condition 3: A rattle or itch-type sound from the instrument panel area near the windshield.


The defroster grill may be rattling due to insufficient retention of the retainers. Press on the defroster grille (Fig. 10) while duplicating the sound to see if it is eliminated.


F10 4224091.jpg-def grill

Fig. 10


Remove the defroster grille and apply foam tape (Fig. 11) around the connectors located under the grille to prevent them from rattling on the grille. Also apply foam tape along the grille.


F11 4224092

Fig. 11


In addition, wrap Kent Automotive BRS flocking tape (P/N KT13487) or equivalent over the 22 metal retaining tabs that secure defroster grill in position.


Once complete, foam tape will be applied to the mounting hooks (Fig. 12, #1) and along the grille (Fig. 12, #2) and flocking tape wrapped over the retaining tabs (Fig. 12 #3).


F12 4224089.jpg-ip def

Fig. 12


– Thanks to David Goodrow

Service Driver Assist Message

On some 2015 Escalade, Silverado, Suburban, Tahoe, Sierra and Yukon models and 2014 Silverado 1500 and Sierra 1500 models equipped with the Safety Alert Seat, a Service Driver Assist Message may be displayed on the Driver Information Center. If the Collision/Detection Systems Alert Type menu in the Vehicle Settings is set to Safety Alert Seat, the driver may notice that the alert type has changed to Beeps. DTCs B172E and/or B172F may be set in the Seat Memory Control Module.


This condition may be caused by an open Driver’s Cushion Haptic Seat Motor (Fig. 13) circuit or high resistance near the motor. (Fig. 14)


F13 4214486

Fig. 13


F14 4214484

Fig. 14


The Safety Alert Seat provides a vibration to alert the driver in certain circumstances. There are two motors in the driver’s seat cushion. Either the right, left, or both motor(s) can run, depending on the alert. The Seat Memory Control Module provides the output voltage for the motors.


Using a scan tool, go to the Seat Memory Control Module and command on the left and right driver’s cushion haptic seat motors. If a haptic seat motor does not operate, follow the appropriate Service Information and perform further diagnosis.


TIP: The haptic seat motor has a pigtail lead coming off the motor. In many cases, the wiring pigtail near the haptic seat motor may be broken. Do not repair the pigtail wiring; replace the haptic seat motor.


– Thanks to Jim Will

Service Know-How

10215.08D – Emerging Issues

August 13, 2015


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





Service Technical College – New Training Courses


Following are the latest service technical courses available to technicians through the GM Service Technical College.


For more information about available service training courses, log in to the GM Center of Learning at and click the Catalog link. Use the drop-down menus to search for courses by delivery type, audience, and category.

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Bulletin Review – July 2015

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