Archive for May 2015

Damaged Suspension Components Due to Vehicle Modifications

There may be some various handling or vehicle dynamics concerns, noises from the suspension or underbody, or issues related to damaged suspension components on some 2007-2013 Escalade EXT, Avalanche; 2007-2015 Escalade models, Silverado, Suburban, Tahoe, Sierra models and Yukon models.


These concerns may occur if the vehicle’s suspension system has been modified by using suspension lift or lowering kits, or making modifications to the vehicle, including adjusting components beyond factory specifications. Examples of these modifications include, but are not limited to, adjusting torsion bar suspensions to change suspension height and/or aftermarket wheels and/or tires installed.


TIP: Before any in-depth diagnostics are performed, technicians should be aware that various issues may occur if the vehicle has been modified. Inform the customer the conditions noted may not be covered under the terms of the New Vehicle Limited Warranty.


Most of the larger lift kits are easy to identify because of the major modifications made as compared to a stock vehicle.


Following are some components to inspect to help identify some of the smaller changes that can still cause handling or noise concerns. If there is any question regarding potential modifications, compare the vehicle to a like vehicle and look for modified components.


Here are some examples of installed aftermarket suspension components:


Aftermarket Lift Kit Block (Fig. 9, #1)


F09 4140820

Fig. 9


Aftermarket Lift Kit Blocks Removed (Fig. 10, #2)


F10 4140824 Fig. 10


Aftermarket Coil Spring Spacer (Fig. 11, #3)


F11 4140832

Fig. 11


Aftermarket Lift Kit Blocks Installed (Fig. 12, #4)


F12 4140839

Fig. 12


Aftermarket Coil Spring Spacer (Fig. 13, #5)


F13 4140843

Fig. 13


Aftermarket Rear Leaf Spring Lift Block (Fig. 14, #6)


F14 4140849

Fig. 14


Improperly Adjusted Torsion Bars


Inspect for improperly adjusted torsion bars (Fig. 15, #7), resulting in improper Z-height adjustments. In this example, the Z-height for this truck would be above the specifications but there is not an actual lift kit installed.


F15 4140855

Fig. 15


Improperly Adjusted Z-Height


The following example shows lift provided by improperly adjusting the Z-height. (Fig. 16) In this example, the front suspension has been raised about three inches.


F16 4140982

Fig. 16


Quality Control Marks


When determining if a vehicle has been modified additional clues can be found by inspecting for quality control marks (Fig. 17, #8)from the factory that are not aligned (especially on new trucks). The green quality control marks do not line up, indicating there has been tampering with this vehicle.

F17 4140857

Fig. 17


– Thanks to Jim Will

Safety Alert Seat Cushion Discomfort

When sitting in the driver’s seat on some 2015 Escalade models, Silverado, Suburban, Tahoe, Sierra, Yukon Models; 2014 Silverado 1500 and Sierra 1500 models equipped with the Driver Alert Package (RPO Y65), it may be possible to feel the left or right haptic seat motor.


The haptic seat motors are located in the seat cushion. (Fig. 7) The haptic seat motors also are called front seat lane departure warning actuators.


F07 3273238 R

Fig. 7


The orientation of the haptic seat motor can be changed to help reduce seat discomfort.


Access both haptic seat motors and rotate the motors flat. Reinstall them into the seat cushion. The different orientation of the motors will help improve the comfort of the seat cushion. Do not attempt to modify positioning of the motors beyond the rotation shown. (Fig. 8)


F08 4163705

Fig. 8


– Thanks to Jim Will

Duramax Diesel Head Gasket Replacement

The following are recommendations and best practices to follow during Duramax diesel cylinder head service or gasket replacement on 2001-2015 Express, Silverado, Savana and Sierra models equipped with the Duramax diesel engine (RPO LB7, LBZ, LGH, LLY, LML, LMM).


Gaskets are Not Interchangeable


The left and right cylinder head gaskets are not interchangeable. (Fig. 6) Improper placement of the cylinder head gasket will block coolant and oil passages. Blocked coolant and oil passages will cause severe engine damage.


F06 gasket

Fig. 6


Surface Cleaning Procedures


Do not use any power type sanding devices. Do not use a wire brush or wheel to clean gasket surfaces. Do not use chemical cleaning agents on gasket surfaces. Refer to Bulletin #00-06-01-012 for more information.


Refer to Service Information and Bulletin #06-06-01-006 for engine block and cylinder head sealing surface cleaning procedures.


Cylinder Head Bolts


During cylinder head servicing or cylinder head gasket replacement, always use new M12 cylinder head bolts. The M8 cylinder head bolts can be reused.


Clean the bolt threads and holes.


Handling Gaskets


Leave the gaskets in the packaging until they are ready to be installed on the block. Once removed from the packaging, handle them with great care.


Do not set the gaskets on workbenches or toolboxes to avoid possible introduction of foreign debris.


Do not use air to blow between the gasket layers.


Cylinder Head Surface


Do not machine the cylinder head surface. Measure the cylinder head for warpage with a straight edge and a feeler gauge. A cylinder head block deck with warpage in excess of 0.1 mm (0.0039 in.) must be replaced.




It is recommended to install two head bolts, secured to minimal torque (20 Nm), prior to installing the remaining head bolts. This will minimize the chance of introducing other foreign material during installation.


Use a paint pen on the M12 cylinder head bolts during installation to mark the head of each bolt, one by one, indicating which of the four torque steps have been completed on that particular bolt. This prevents skipping a step or doing a step twice. In the end, all bolts should have four paint pen marks.


– Thanks to John Stempnik

Comfort Open/Remote Venting Windows

On some 2013-2014 XTS and 2014 CTS Sedan (VIN A) models, the windows may roll down when this operation is not desired after using the Remote Keyless Entry (RKE) transmitter (key fob). Some owners may have found all windows were down when returning to their vehicle.


These models may be equipped with the comfort open or remote venting window feature, which enables users to lower the windows from outside the vehicle by pressing and holding the Unlock button on the RKE transmitter. (Fig. 5) The Unlock button must be held long enough for the windows to start lowering to the full open position. Pressing the Unlock button again will cause the window movement to stop.


F05 CTS key fob

Fig. 5


The comfort open/remote venting windows can be turned off if requested by the owner. This should only be done if the owners requests the feature be turned off.


On CTS Sedan (VIN A) models, contact the Techline Customer Support Center to obtain a VCI number to disable this feature.


For XTS models, reprogram the BCM. The selection option to disable this feature is found in the “Locking” section.


– Thanks to David Antal

Unseated Pins in the Transmission Connector

On some 2006-2011 STS; 2007-2009 SRX; 2008-2014 CTS (VIN D) built prior to May 1, 2014; 2013-2014 ATS built prior to May 1, 2014; and 2014 CTS Sedan (VIN A) built prior to May 1, 2014, equipped with a 6-speed automatic transmission, there may be one or more of the following conditions:

• Service Engine Soon lamp illuminated

• Reduced power

• Engine will not crank over, no start

• Multiple warning lamps illuminated

• Transmission shifts hard

• Door locks cycle while driving


The Transmission Control Module (TCM) or Engine Control Module (ECM) may not communicate with the scan tool. The following DTCs may be set: C0242, C0561, P0575, P0615, P0700, P0856, P1629, P2544, U0073, U0074, U0100, U0101, U0109, U0121, U0140, U2100, U2105, and U2106.


These conditions may be caused by an unseated pin(s) in the transmission connector.


Inspect the transmission connector X1 terminal connections. Disconnect the connector and carefully tug on each wire to ensure the pins are fully seated. A side load on the wires may cause a false positive lock. Repair the connections as necessary.


– Thanks to David Roat


Mobile Device Wireless Charging Update

The Wireless Charging system for smartphone is an inductively coupled means for wirelessly charging mobile devices in the vehicle; no cables necessary.


It’s available on 2015-2016 ATS, CTS sedan, Tahoe (Fig. 4), Suburban, Yukon models, and Escalade models. It will be offered on additional models for the 2016 model year.


F04 charging mat

Fig. 4


On ATS and CTS sedan, the wireless charging system is located in the hidden storage compartment behind the climate control panel below the Cadillac CUE screen. On the full-size SUVs, the system is located on the top of the center console armrest.


An increasing number of smartphones have built-in wireless charging technology. Some smartphones require a wireless capable back cover or adapter. Customers should contact their phone retailer for information about a wireless charging adapter/back cover if it’s required for their phone.


A compatible device is one that is compliant with the Power Matters Alliance (PMA) or Wireless Power Consortium’s (WPC) Qi Standard, meaning that it is equipped with a PMA or Qi wireless charge “receiver” that will work with the charge “transmitter” installed in the vehicle. A device may use built-in charging circuitry or an adapter (external plug-in device which contains the charging circuitry).


Charging a Device

1. To charge a device, with the vehicle ignition on, place the device, face up, on the charging symbol on the charging mat (all other objects should be removed from the charging surface).

2. Adjust the position of the device slowly until the battery charging symbol displays on the infotainment touch screen, indicating the device is charging.


TIP: If the device does not charge, verify it is properly positioned on the charging surface. It may be necessary to rotate it 180 degrees to help establish a connection. Do not slide the device. Pick it up to reposition it. Also, the use of a protective case may require more precise placement or may inhibit charging. Try removing the case.


There is a charging coil located in the center of the charging surface and the mobile device has a charging coil typically near the center of the device. These coils must be lined up in order for charging to proceed.


When the Interruptible Retained Accessory Power (IRAP) relay is closed (when the vehicle ignition is in Run or Accessory position), the system is able to detect the device, establish communications with the device to confirm it is a compatible device, and then deliver charging power to the device via the wireless interface.


If a non-compatible device or metallic foreign object is detected, the system will not transfer power. The charger monitors its internal temperature and will shut down if it the charger temperature exceeds 185° F (85°C).


The BCM will detect the device battery is charging and send a serial data message to the infotainment touch screen, which will indicate a device is currently charging. When the indicator is toggling on and off, it indicates a thermal limit has been reached and the device will not charge. It is normal for the phone temperature to increase during the charging process.

Charging also may be interrupted while driving over rough conditions. Reposition the mobile device to continue charging.


TIP: For any Wireless Charging system concerns, refer to circuit/system verification and testing in the appropriate Service Information. A scan tool cannot be used since the system is not connected to any control module. No DTCs or data parameters are available.


Compatible Devices


For the latest information about mobile device compatibility with the wireless charging system, go to


A PDF of Wireless Charging compatible devices can be downloaded from the website.


– Thanks to Hassan Abdallah

Service Information Circuit/System Verification Changes

Based on feedback from GM field service engineers, the Technical Assistance Center (TAC), GM service trainers and dealership service technicians, there have been a few cases documenting the difficulty of isolating an issue using the diagnostic procedure Circuit/System Testing category in the Service Information. In most cases, the Circuit/System Verification was not performed. If the verification procedures were performed prior to the circuit testing, the correct issue would have been found and corrected.


For example, Circuit/System Verification refers to diagnosing a 5V reference DTC P0641 before the sensor DTC.


As a result of these reports on testing and verification, the Diagnostic Procedure Instructions (linked at the top of any diagnostic procedure in the Service Information) has been modified. (Fig. 2)


F02 circuit 1

Fig. 2


Determining a Current Condition


Originally, the Diagnostic Procedure Instructions did not instruct a technician to perform any of the three diagnostic categories — Circuit/System Verification, Circuit/System Testing, and Component Testing — in a specified order. However, performing the procedures in the Circuit/System Verification category first aids in determining if a vehicle condition is current.


The Service Information has been changed to reflect this. The Diagnostic Procedure Instructions explain that, when supported, Circuit/System Verification needs to be performed prior to the Circuit/System Testing. The verification procedures will determine the following conditions:


• If a higher priority concern needs to be addressed first (e.g., other DTCs)

• If other conditions are present (e.g., low fluid level)

• If the condition is current

• If the condition is intermittent

• If the system is all OK



Repair Verification


Other changes regarding the Circuit/System Verification include modifications to the Diagnostic Repair Verification information. The link to the Diagnostic Repair Verification is in the Repair Information category. (Fig. 3)


Step 7 now includes the additional information:

7.   Perform the Circuit/System Verification and verify the result ends with an All OK.


It is recommended to perform the Circuit/System Verification to validate a proper repair has been made.


F03 circuit 2

Fig. 3


– Thanks to Andreas Mueller, David Miller and David Nowak

The Beginnings of a New Bulletin

Things change fast in the automotive world. Products and components may require repairs that need to be made immediately or service procedures need to be updated. So how are these conditions found? And how does the word get out to dealerships?


There are many ways General Motors communicates with dealership technicians about diagnostic repairs and other information that are not included in a standard Service Information (SI) document. One method is for the Technical Assistance Center (TAC) or the Brand Quality group to publish a PI (Preliminary Information)/Bulletin.


F01 bulletin art

Fig 1


Find the Cause


The first step is for TAC or the Brand Quality group to identify the need for this type of service communication, which is done by monitoring various sources, including Field Product Reports (U.S.) and Product Information Reports (Canada), TAC cases, field service engineers’ reports, dealer calls, and the product action centers.


Once the need is identified, it is necessary to gather all of the concern, cause, and correction information. For some conditions, this is very easy and self-explanatory. In other cases, it is necessary for TAC and/or the Brand Quality Manager to work with engineering, field service engineers, Service Learning Center technicians, and/or local dealerships to gather all the necessary information.


Write the Repair


After all concern, cause, and correction information is gathered, a Brand Quality bulletin team author or TAC escalation team author creates a draft outlining the condition and correction. In some cases, existing repair procedures and labor operations found in the Service Information are utilized for standard repairs and diagnosis. Other times, everything may be available but it may be necessary to obtain photos of components or repairs on the vehicle. Photos or other documentation may be obtained from GM fleet vehicles, local dealerships, engineering, or field service engineers.


If a complete repair procedure has to be created, a Brand Quality bulletin author will work with the Brand Quality Manager and an onsite Service Learning Center technician to document the diagnostic/repair steps, take photos, determine what parts are needed, and develop a labor time.


Stock Parts


In the event that parts are going to be required, a “service part alert” is created to ensure that Customer Care & Aftersales (CCA) has appropriate parts stock available for dealerships to order before the PI/Bulletin is released in an effort to prevent a back-order situation.


Once the draft is complete, the final draft is created and reviewed before being published in the Service Information. Depending on the topic, many PI/Bulletins are forwarded to be published as a GM Techlink article and also considered as topics for the monthly Emerging Issues broadcast (U.S.) or TAC Talk broadcast (Canada). There are some instances where a Global Connect message is sent to dealerships to call additional attention to a recently released PI/Bulletin — particularly when a repair was not available when the PI/Bulletin was initially published.


– Thanks to Jamie Parkhurst


CH-51450-A Oscilloscope Diagnostic Kit with NVH Released as Essential Tool

GM has begun shipping the CH-51450-A NVH Kit as an essential diagnostic tool to all GM dealerships. Shipments will continue through July 2015.


The CH-51450 NVH Kit (Fig. 1) was first released last year as the replacement of the J-38792-A Electronic Vibration Analyzer (EVA). U.S. dealerships with a damaged or missing EVA were the first to receive the new NVH diagnostic oscilloscope kit.


F01 NVH kit

Fig. 1


To assemble the NVH diagnostic kit, GM partnered with Pico Technology to develop a GM-specific, 4-channel, PC-based automotive oscilloscope with NVH vibration diagnostics and driveline balancing capabilities. The tool is designed to help identify the slightest chassis & driveline disturbances on today’s increasingly sophisticated vehicle architectures.


The CH-51450-A Kit includes a 3-axis accelerometer and interface to provide accurate analysis of vibrations in all directions. Using the display of your existing laptop computer, this system combines fast capture and analysis of vehicle data with a clear easy-to-read presentation of results and actions. Recordings can be captured while on a road test for analysis as well as saved to the laptop’s hard drive for further review back at the dealership.


The software is compatible with Windows Vista and Windows 7.


When performing driveline balancing analysis, step-by-step procedures are provided for pinion flange, dual hose clamp and trial weight balancing.

Screen Shot 2015-05-11 at 3.09.18 PM

TIP: The CH-51450-A Kit contains a 3-axis accelerometer, whereas the original CH-51450 kit includes a single-axis accelerometer. For a limited time (August –December 2015), dealerships with a CH-51450 Kit may purchase a 3-axis accelerometer sensor and interface (CH-51450-KP134) for $298.70 (USD) through 1-800-GM-TOOLS.


The kit works with the Multiple Diagnostic Interface (MDI) or any J2534 interface to acquire vehicle data. It also can be used without a scan tool, which may be particularly useful for older non-OBD vehicles.


The tool’s recording feature is defaulted to capture 50 seconds of data. Begin capturing data by pressing the “Start Recording” button. While data will continue to scroll through the window, it will only capture what is visible on the screen when the “Stop Recording” button is pressed. The data can be manually saved to the PC’s hard drive to be played back later for analysis or sharing.


The test drive trace recording default is a maximum of 50 seconds. However, up to 500 seconds of data can be recorded. An unlimited number of road tests, stored as laptop data files can be attached to customer records. The data files also can be emailed, making it easier to get assistance from the GM Technical Assistance Center during NVH diagnosis.


NVH Training Courses


The following GM Training courses are available that include overview, set-up and demonstration of the CH-51450 NVH kit:


13042.12W – Noise, Vibration and Harshness (Web course)

13042.14D1 – Noise, Vibration and Harshness 1 (VCT course)

13042.14D2 – Noise, Vibration and Harshness 2 (VCT course)

13042.13V – PicoScope Noise, Vibration, and Harshness Diagnostics Overview (NVH oscilloscope video)

13042.14H – Noise, Vibration and Harshness (Hands-on course)


– Thanks to Chuck Berecz

GDS 2 Update Enables Users to “Contact Us”

The latest GDS 2 software update (14.0.x) recently released provides users with a new way to provide feedback or ask questions about the diagnostic software application.


Feedback Options


After updating GDS 2 to 14.0.x, users can click the Contact Us button at the bottom of the screen (Fig. 2) to open an Internet browser that explains two different ways to provide feedback to GM: either through a survey or reporting a specific issue. The Contact Us instructions are dependent on the selection of the diagnostic package. There are different instructions for the various diagnostic packages.


F02 gds2 contact us button

Fig. 2


TIP:  A diagnostic package must be selected for the Contact Us button to be enabled.


If immediate help with GDS 2 is needed, contact the Techline Customer Support Center at 1-800-828-6860 (English) or 1-800-503-3222 (French).


The survey option instructions presented after selecting Contact Us explain how to provide feedback on several Techline applications. To complete an online survey on GDS 2, click the Surveys button at the top of the TIS2Web home page. From the list of surveys, select GDS 2. (Fig. 3)


F03 online survey

Fig. 3


To report a specific issue or concern, click the Feedback button at the top of the TIS2 Web home page. (Fig. 4) In the Feedback Type drop-down menu, select GDS 2, and then provide the specific information requested.


F04 feedback form

Fig. 4


New Features


Release 14.0.x also updates the Select Device button. Clicking this button prompts the user to select a device type (e.g. MDI, MDI 2) before selecting a J2534 device. (Fig. 5)


F05 gds2 device type

Fig. 5


In addition, the DTC displays have changed. For a single module DTC display, the DTC summary screen and DTC display screen are now combined into one screen, reducing the number of screens to view and consolidating DTC information. (Fig. 6)

F06 gds2 dtc screen

Fig. 6


– Thanks to Chris Henley

Loss of Isolation Testing on High Voltage Systems

The following technical information is intended to inform professional service technicians about Loss of Isolation testing on high-voltage vehicle systems.


The high voltage system in the Volt (Fig. 7), ELR and Spark EV is isolated from the vehicle. It has virtually no contact with the low voltage system or chassis of the vehicle. The high voltage battery and each high voltage device have both positive and negative cables, or in the case of the drive motors, three high voltage AC cables. The vehicle chassis is not used to supply a return path for high voltage at any time. During normal operation, high voltage should always be isolated from the vehicle chassis by a certain amount of resistance as a safety precaution.

F07 Volt HV

Fig. 7


A loss of isolation can be viewed simply as a short between the high voltage system and the chassis. The Hybrid/EV system monitors several high voltage components for attempted access and loss of isolation, which occurs if the positive or negative high voltage DC circuits or any of the high voltage AC phase circuits lose their isolation from the vehicle chassis. If such a condition were to occur, it may be intermittent and may be related to faults in the high voltage wiring, connections or components.


Insulation Multimeter


Similar to typical 12V vehicle systems, loss of isolation can be as simple as a direct conductor-to-chassis short. However, unlike 12V systems, the potential within high voltage systems means that insulation breakdown is also a cause for loss of isolation. Insulation breakdown typically occurs only when high voltages and/or current is present.


Conditions such as insulation breakdown cannot be diagnosed with a typical digital multimeter (DMM) because high voltage is not used by the DMM when measuring resistance. An Insulation Multimeter (EL-50772), which uses its own built-in high voltage, must be used to test the isolation capability of high voltage components and circuits. (Fig. 8)


In addition, monitoring certain scan tool parameters when high voltage is active also may help in identifying which high voltage components and circuits may have lost their chassis isolation.


F08 loi meter

Fig. 8


TIP: Always perform the high voltage disable procedure as published in the appropriate GM Service Information before servicing high voltage components and wiring and always wear the proper personal protective equipment.


Passive and Active Isolation Testing


The vehicle uses passive and active isolation testing to determine the amount of isolation between the high voltage and the chassis.


Passive isolation testing is performed within the Power Inverter Module (PIM) and tests whenever the high voltage main contactors are closed. Using a high impedance resistor network, passive isolation detection monitors all high voltage components. Real-time status of passive isolation detection can be determined by observing the delta between the Positive Supply Isolation Voltage and Negative Supply Isolation Voltage scan tool parameters. The parameters are displayed by any of the Motor Control Modules.


Active isolation testing is performed by the Hybrid Powertrain Control Module 2 and tests after the high voltage main contactors open. Using an injected AC signal, active isolation detection monitors the internal Hybrid/EV battery pack and the charging system (DC) high voltage circuits.


Status for the prior active isolation detection event can be determined by observing the Hybrid Powertrain Control Module 2 Isolation Test Resistance scan tool parameter. Real-time status observation requires the HPCM2 scan tool control function Hybrid/EV Battery Pack Isolation Test.


Scan Tool Parameters


Monitoring certain scan tool parameters when high voltage is active may help to identify which high voltage components and circuits have lost their chassis isolation. The Vehicle Information selection within the HPCM2 scan tool Data Display contains many parameters related to isolation diagnosis. (Fig. 9)


F09 loi vehicle information

Fig. 9


The Drive Motor 1 Control Module Positive Supply Isolation Voltage and Drive Motor 1 Control Module Negative Supply Isolation Voltage parameters provide a real-time indication of isolation status. The parameters will shift in respect to one another relative to the level of isolation loss. The greater the delta, or difference, between parameters, the less isolation exists between high voltage and the vehicle chassis.


Certain isolation loss concerns may only appear during high moisture environmental conditions. Driving the vehicle through an underbody spraying-style car wash while monitoring the delta between the Positive Supply Isolation Voltage and the Negative Supply Isolation Voltage scan tool parameters may reveal an isolation loss concern.


Isolation loss also might only occur when a high voltage device is active. Use the High Voltage Component Test Method table and operate each HV component while monitoring the delta between the Positive Supply Isolation Voltage and the Negative Supply Isolation Voltage scan tool parameters.


Diagnosis with an Insulation Multimeter


The EL-50772 Insulation Multimeter tests the isolation capability of high voltage components and circuits. For correct test results, the functions of the insulation multimeter must be used properly.

• Plug into the correct ports (1, 2) for insulation testing. Do not use ports (3, 4) for insulation testing. (Fig. 10)


TIP: It is critical that the correct ports (1, 2) are used for insulation testing. This is easy to get wrong, especially if the EL-50772 is used for standard DMM testing too. Do not use ports 3 and 4 for insulation testing. Also, if port 1 and port 4 are mistakenly used, continuity testing will still function, but the insulation test will always appear to pass.


F10 loi meter cables R

Fig. 10


• Always test at the 500V range.

• With the test leads not connected to anything, press and hold the insulation test button to know how your meter displays an infinite measurement. The EL-50772 will display 550M Ω when measuring an open circuit while set to the 500V range. (Fig. 11)


F11 loi 550

Fig. 11


• With the test leads connected together, press and hold the insulation test button to see how your meter displays continuity. The EL-50772 will display 0.0 Ω.

• When performing insulation testing, a good ground reference is needed. When possible, use an alligator clamp to attach the ground lead. Typically, the reference point will be to the vehicle chassis, except cable testing, which requires connection to the cable shield termination at the connector and not to the chassis.

• Verify the ground connection prior to every test measurement at a suitable ground location near the test point. The EL-50772 should display 0.0 Ω, indicating continuity.

• When testing components with large capacitance or inductance, such as certain modules and larger motor stators, it may be necessary to hold the insulation test button for a few seconds until the maximum resistance value is displayed.


Video Demonstration (U.S.)


For more information about loss of isolation testing, check out the March 2015 edition of the Emerging Issues seminar (10215.03D). It includes a video demonstration using an insulation multimeter.


Training Courses (Canada)


• 18421.16H – Electric Vehicle Battery Diagnosis & Service

• 18420.05D1 and 18420.05D2 – Electric Vehicle Systems Diagnosis and Service


– Thanks to Steve Falko and Joe Ciagala

OnStar and XM Antenna Malfunctions

On some 2015 Escalade, Silverado, Suburban, Tahoe, Sierra and Yukon models equipped with a high-frequency painted antenna assembly (Fig. 12), one or more of the following symptoms may be present:

• Visible water leak or signs of water intrusion from the antenna base

• Red OnStar LED

• Unable to connect to OnStar

• OnStar unable to locate the vehicle

• OnStar has inaccurate GPS location

• No GPS or inaccurate GPS location on the navigation radio display


These conditions may be accompanied by DTC B2462-02, B2462-04, B2470-02, B2470-04, B125C-01, B125C-02, or B125C-04.

F12 Antenna

Fig. 12


Water intrusion into the antenna assembly may result in any of the conditions listed above. If these conditions are encountered, replace the antenna and use the new updated antenna cover.


Do not remove the cover from the base. Mask and spray paint the cover to match as necessary.


Do not use any sealants on the antenna or its seals/gaskets.


TIP: The painted antenna cover is not intended to be removed. Do not remove the antenna cover as this may compromise the sealing performance. Do not reuse the original antenna painted plastic cover. The latest service parts include updated covers.


– Thanks to Brian Ouelette

Water Leak Diagnostic Tips

A water leak into the cab, water staining of the headliner or water on the floor may be found on some 2015 Colorado or Canyon models.


To diagnose these water leak conditions, follow the appropriate procedures in the Service Information for Water Leak Diagnosis. In addition, inspect the following areas:


Roof ditch – Pin holes in the roof ditch sealer at the front and rear may allow water intrusion in the vehicle. At the front, water may run behind the A-pillar trim, along the edge of the instrument panel and drip on the kick panel. At the rear, water may enter on the inside of the glass very close to the roof ditch seam. A void along the seam may allow water to enter in either the front or the rear.


Rear glass –Back glass sealer voids may be caused by hand-installing the back glass. If the glass locating pins are not seated in the locating hole, the glass could be out of position and allow a leak point near the dislocated pin.


CHMSL – Water may travel along the rear header to the roof flange and can enter the vehicle anywhere along the back glass, appearing to be a back glass leak.


Windshield – If the windshield is not located properly, the locating pin could slide below the locating hole, allowing the windshield to set low. If the windshield is too low, the VIN plate will be covered.


Cowl seam – Water may accumulate on the floor. Inspect the front of the dash/bulkhead for leaks at the mid area and also near the floor along the seam of the front of the dash-to-bulkhead. The front of the dash has two tooling hole plugs that may allow water if not installed correctly.


HVAC drain tube – Water may soak the front floor area on either side if the drain tube is dislocated. It is more likely to be reported during A/C operation in high humidity conditions.


A-pillar area – Inspect for missing sealer at the door hinges. Also inspect for a weld-through condition along the outer pillar/bulkhead-to-fender support that leads straight to the inside of the front bulkhead. There are also three welds on the top of the pillar/bulkhead for the fender bracket. The baffles hold the water in the pillar/bulkhead where it pools while seeping into the cab through the harness rosebud holes. Also inspect the pillar plug or the door boot not being seated.


Water collecting in the sill area – The door may freeze in areas with large temperature swings or water may run onto the driver’s foot when opening the door. This is a water management issue this is being reviewed by Engineering.


PRV (Pressure Relief Valve) – Water runs along the back panel and down to the front foot area if the valve is not fully seated.


– Thanks to Ernest Haller


Full-Size Truck Instrument Panel Cluster Replacement

If the instrument panel cluster (IPC) (Fig. 13), which is on parts restriction, requires replacement on 2014 Silverado 1500, Sierra 1500; 2015 Silverado, Suburban, Tahoe, Sierra and Yukon models, authorization must be received from the Techline Customer Support Center (TCSC) or the GM Technical Assistance Center (TAC), depending on the reason or replacement (U.S. dealerships only).


F13 IPC Tahoe

Fig. 13


Programming Event


If the instrument panel cluster locked up during an SPS Programming event, verify if the instrument panel cluster can be recovered by performing the following steps:


• Do not turn off the ignition. Check that all instrument panel cluster, DLC and programming tool connections are secure and the TIS terminal operating software is up to date.

• Attempt to reprogram the instrument panel cluster. Select programming process Replace and Program ECU in TIS2Web.

• If the instrument panel cluster can still not be programmed, turn off the ignition, disconnect battery and wait for at least two minutes.

• Connect battery, turn on the ignition, select programming process Replace and Program ECU and attempt to reprogram the instrument panel cluster. The instrument panel cluster should program.




Refer to #PI1212A for more information.


If the instrument panel cluster programming cannot be completed after following the recommended steps, contact TCSC for further assistance. If the instrument panel cluster is not able to be recovered, TCSC will authorize an instrument panel cluster replacement. GM TAC does not need to be contacted for authorization. After contacting TCSC, contact your ESC with the TCSC case number to order a replacement instrument panel cluster.


Instrument Panel Cluster Conditions


If the vehicle came in with an instrument panel cluster condition, such as inoperative gauges or cluster display malfunctions, and normal diagnostics lead to instrument panel cluster replacement, contact TAC to review the diagnosis. If necessary, TAC will authorize instrument panel cluster replacement.


It is not uncommon for the dealership to receive a different part number than the one ordered due to a normal part number supersession or if the new unit is a remanufactured assembly.


– Thanks to Scott Fibranz

Increased Seat Motor Noise

There may be an increased power seat motor noise when moving the driver or passenger seat forward or backward using the Easy Entry power seat switch or the power seat switch on the 2015 ATS coupe and 2014-2015 ELR compared to vehicles without the Easy Entry feature. The Easy Entry power seat switch is located at the top of the seat back.


Do not replace the seats or motors for this condition. All Easy Entry seats are the same.


The Easy Entry power seat adjustment motors in the ATS Coupe and the ELR are unique. They run at a different rate and produce more noticeable noise than other vehicle models without the Easy Entry feature.


Compare the noise level of both seats using the Easy Entry seat switch and the power seat switch on the side of the seat to determine if there is a noticeable difference in the driver and passenger seat. Compare an ATS Coupe to another ATS Coupe or an ELR to another ELR. Do NOT compare the noise level to an ATS Sedan or CTS VIN A Sedan as those seat motors are different.


– Thanks to Stephen Jacob

Special Edition Paint Codes

Dealerships may have difficulty locating the correct paint code for the following special edition vehicle models:

2003-2005 Deville – Mary Kay Edition

2003–2004 Seville – Mary Kay Edition

2004 XLR – Neiman Marcus Edition

2006–2011 DTS – Mary Kay Edition

2007–2011 STS – Mary Kay Edition

2009–2015 CTS, SRX – Mary Kay Edition

2013–2015 ATS, XTS – Mary Kay Edition

2011 Camaro Convertible – Neiman Marcus Edition

2013 Camaro – Hot Wheels Edition

2015 Camaro – Green Flash Edition


When performing exterior body refinish/paint repairs on any of these vehicles, use the following paint codes:

• 2003 Mary Kay Cadillac models – paint code WA-160E: Mary Kay Pink Pearl

• 2004–2007 Mary Kay Cadillac models – paint code WA-983L: Mary Kay Pink Pearl III

• 2004 Neiman Marcus Cadillac XLR – paint code WA-111B: Majestic Amethyst Metallic

• 2008-2015 Mary Kay Cadillac models – paint code WA-590Q: Mary Kay Pink Pearl V

• 2011 Neiman Marcus Chevrolet Camaro convertible – paint code WA-724S: Mystic Bronze Tri-coat (exterior body color); paint code WA700T, Ghost stripes (hood and decklid)

• 2013 Hot Wheels Chevrolet Camaro – paint code WA-720S: Kinetic Blue (exterior body color); paint code WA-799U: Performance Red, Red stripe (wheels and front bumper)

• 2015 Green Flash Camaro models – paint code WA-136X: Unripened Green (Fig. 14)


F14 camaro

Fig 14


– Thanks to Matt Bierlein

Service Know-How

10215.05D – Emerging Issues

May 14, 2014


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 – April 2014

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