Archive for October 2016

New 2017 Colorado and Canyon Action Center Now Available

A new GM Technical Assistance Center (TAC) Action Center has been established for the 2017 Colorado and Canyon (Fig. 1) equipped with the new high feature 3.6L V6 engine (RPO LGZ) and 8L45 8-speed transmission (RPO M5T). The Action Center is available to provide dealerships with additional support for the introduction of this new powertrain.



Fig. 1


Dealerships are asked to call the Action Center regarding any powertrain performance or operation conditions. The Action Center is connected directly to TAC, Engineering, and the assembly plant so that any product concerns can be resolved quickly.


GM encourages dealerships to report all product conditions, not just those requiring technical assistance. Digital photos and audio/video files for various conditions also may be requested.


Compared to the previous 3.6L V6 engine, RPO LGZ features improved variable valve timing and direct injection along with Active Fuel Management, which disables two cylinders under light throttle applications.


Featuring four gearsets and five clutches, the 8L45 transmission fits in the same space as the previous 6-speed transmission while offering added efficiency.


– Thanks to Charles Hensley

Battery Learn Procedure Update for Stop/Start System

A new Power on Reset feature has been added to 2017 models equipped with Engine Stop/Start. As a result, the battery learn procedure is no longer required after a battery disconnect on 2017 Encore, Envision, LaCrosse, Regal, Verano, ATS, CT6, CTS, XT5, Cruse, Impala, Malibu, Trax, and Acadia (VIN N) models with Engine Stop/Start (RPO KL9). The Battery Sensor Module 3-hour learn procedure has been removed from the Service Information for these models. 2017 models with Stop/Start have an AUTO STOP position on the tachometer. (Fig. 2)



Fig. 2


With the Power on Reset feature, the following parameters were added to the Diagnostic Aids section of the Service Information – Stop/Start Malfunction:

• Battery Sensor Module Battery State Information = Available/Not Available • Battery Sensor Module Reset Occurred – Using Estimated State of Charge = Yes/No


GDS 2 will display these parameters under Engine Control Module > Stop/Start System Data.


Power on Reset is active when the parameters read:

• Battery Sensor Module Battery State Information = Not Available (Not Learned), and • Battery Sensor Module Reset Occurred – Using Estimated State of Charge = Yes (Estimated).

The Stop/Start system is enabled when Power on Reset is active.


The vehicle will continued to use an estimated state of charge until it sits for three hours. It will then start using the actual state of charge value from the Battery Sensor Module. (Fig. 3, 2017 LaCrosse shown) The Engine Stop/Start feature will function normally before and after the learn occurs.



Fig. 3


– Thanks to Rob Ritz

Electrical Conditions Resulting from Damaged Wiring Harness

A number of electrical conditions, including the instrument cluster gauges drop out, the radio and HVAC displays are blank, no crank/no start, and several Driver Information Center messages displayed, may be present on some 2013-2014 Malibu models. The air bag fuse may be blown and several communication DTCs may be set. These conditions may be caused by the wiring harness rubbing against the seat frame or a short to ground in the 5060 circuit.


To duplicate these conditions, the passenger seat must be occupied. If the conditions are found, inspect the passenger-side seat wiring harness (Fig. 4, #1) for possible damage and improper routing through the seat frame. (Fig. 4, #2)



Fig. 4


If the harness (Fig. 5, #1) is damaged or improperly routed, remove the passenger seat and re-route the harness away from the frame. Disconnect the electrical connector (Fig. 5, #2) if necessary.



Fig. 5


Also inspect the harness for any chafing or exposed wire. Repair the harness as needed and wrap the harness using a double layer of Woven Polyester Electrical Tape. (Fig. 6, #1) Secure the harness to the seat wiring harness with Woven Polyester Electrical Tape. (Fig. 6, #2)



Fig. 6


– Thanks to Ron Caponey

Power Liftgate Latch Connector

The power liftgate on some 2017 Acadia and XT5 models may not open. When diagnosing the liftgate will not open condition, disconnect and reconnect the latch electrical connector and retest power liftgate operation, making sure the connector is fully seated. This should be done prior to replacing the liftgate latch assembly. (Fig. 7)



Fig. 7


Replaced latches returned to the Warranty Parts Center that have undergone testing have shown no trouble found. Based on the documented repairs, the only change being made to the affected vehicles is disconnecting and reconnecting a new latch. Be sure to inspect and disconnect/connect the electrical connection of the latch prior to any component replacement.


If the power liftgate does not function properly after the electrical connector has been disconnected and reconnected, follow the diagnostics in the appropriate Service Information.


Diagnosis should include checking the calibration software installed on the liftgate control module prior to performing extensive diagnostics. Vehicles with the hands-free liftgate require specific calibration software. Incorrect calibration software may cause the power liftgate system to be inoperative without setting any DTCs.


– Thanks to Tom Burlingame

Inoperative Sunroof or Sunshade

On some 2016 CT6, Malibu (VIN Z); 2017 XT5 and LaCrosse models, the sunroof glass and/or sunshade may be inoperative.


Several DTCs may be set: B3664 (Sunroof Position Select Switch High Signal Circuit), B3697 (Sunroof Actuator Malfunction), B369B (Sunroof Sunshade Position Select Switch Circuit), B369C (Sunroof Tilt Position Select Switch Circuit), B369D (Sunroof Sunshade Actuator Malfunction), U1517 (K9 Body Control Module Lost Communication with K62 Sunroof Sunshade Motor Module on LIN Bus) and/or U151B (K9 Body Control Module Lost Communication with K61 Sunroof Control Module on LIN Bus).


It may be necessary to replace the sunroof wiring jumper harness to address this condition. Inspect the sunroof wiring harness label date codes. (Fig. 8)

• If the harness code is prior to 6QK (June 25, 2016), replace the harness. • If the harness code is after 6QK, inspect the sunroof motors following the diagnostics in the appropriate Service Information.



Fig. 8


TIP: Do not replace the sunroof motor, sunshade motor or overhead console. Verify the build date of the sunroof wiring harness prior to replacement of any other components.


Before replacing the sunroof wiring jumper harness, disable the SIR system. Lower the headliners from the rear up to the B-pillar to access the harness. Disconnect the harness from the sunroof window motor to the headliner harness. Connect the new harness and clip it to the headliner from the sunroof motor to the headliner harness. Do not change the wiring harness routing location. The proper harness routing is critical for air bag deployment.


– Thanks to Ed Flanagan

Unseated Exhaust Pipe Connector Leak

An exhaust leak or noisy exhaust, sometimes described as a rattle or rumble, most noticeable on a cold start may be found on some 2014-2017 Silverado 1500 and 2015-2017 Escalade, Suburban, Suburban 3500, Sierra, and Yukon models. The exhaust leak may be due to an unseated pipe-to-pipe mid-joint connection. (Fig. 9)



Fig. 9


To correct the exhaust leak, remove the exhaust band (Norma) clamp and install a new exhaust band (Norma) clamp to the pipe joint.


When installing the new clamp, firmly push the pipes together and maintain the connection while tightening the exhaust band clamp bolt to 30 Nm (22 lb.-ft.).


The clamp does not need to be perpendicular to the pipe. (Fig. 10) Confirm the clamp edges are fully seated on the pipe on both sides all the way around the clamp. Once the new clamp is installed, run the engine and inspect the clamp joint to ensure there are no exhaust leaks.



Fig. 10


– Thanks to Richard Renshaw

Harsh Shift and Rough Idle Conditions

A harsh shift and rough idle may be felt on some 2014-2017 Corvette, Silverado, Sierra; 2015-2017 Escalade, Suburban, Tahoe, Yukon; 2016-2017 CTS-V, and Camaro models.


The harsh shift may be felt on the 1/2 and 2/3 shift along with a sputter when applying the throttle between 0% and 30 % and a rough idle. DTCs P0101 (MAF Sensor Performance), P0171 (Fuel Trim System Lean Bank 1), P0172 (Fuel Trim System Rich Bank 1), P0174 (Fuel Trim System Lean Bank 2) and P0175 (Fuel Trim System Rich Bank 2) may be set.


Inspect for cast flashing in the air filter housing near the Mass Air Flow (MAF) sensor for excessive flashing. (Fig. 11) If excessive flashing is found, replace the air filter housing lid. Be sure to check the flashing in the new lid as well.



Fig. 11


– Thanks to Richard Renshaw

Engineering Information Bulletins and Part Restrictions


Service Know-How

10216.12V – Emerging Issues

December 8, 2016


The latest service topics from Brand Quality and Engineering are reviewed, including an overview of the new 2017 Bolt EV and the repair procedure for a water leak around the CHMSL on some 2016-2017 Cruze models. (Fig. 12)



Fig. 12


To view Emerging Issues seminars:

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

Malibu Hybrid No Crank Condition and DTC P0AFA

If the 1.8L engine (RPO LKN) on a 2016-2017 Malibu Hybrid model (Fig. 1) does not crank after several attempts and DTC P0AFA (Hybrid/EV Battery System Voltage Low Voltage) is set, it may be necessary to replace the high voltage battery pack.


2016 Chevrolet Malibu Hybrid Lithium-Ion Battery System, 1.8L EnFig. 1


After excessive engine crank attempts where the engine turns over but does not start, the high voltage battery pack will be drained of power, similar to draining a 12V battery in a traditional powertrain.


The high voltage battery pack stores 288V DC in eight lithium–ion battery sections. (Fig. 2) The high voltage battery pack is charged during normal vehicle driving and is maintained at or near an optimum level of charge.


2016 Chevrolet Malibu Hybrid Lithium-Ion Battery System

Fig. 2


Excessive Engine Starts


Requesting excessive vehicle starts by pressing the Engine Start-Stop button will cause the high voltage battery pack to drain. It’s recommended that drivers do not attempt more than 10 engine starts using the Engine Start-Stop button without driving the vehicle to ensure the battery pack is charged. Too many engine starts may require replacement of the high voltage battery pack.


If the green “Ready” light (Fig. 3) on the instrument cluster is displayed, the vehicle is ready to drive. Normally, the vehicle should enter the green “Ready” state on the very first start attempt. If it does not, there may be some other issue, such as the fuel system, which prevents the gasoline engine from starting. Avoid unnecessarily draining the high voltage battery pack until the root cause is corrected.



Fig. 3


If 10 start events are reached and propulsion is still not available (no green “Ready” light on the instrument cluster), begin diagnosis following the appropriate Service Information and contact TAC for additional diagnostic assistance.


Prolonged Operation in Neutral


Inadvertently leaving the Malibu Hybrid in Neutral for prolonged periods (more than 5 minutes) will cause both the 12V battery and the high voltage battery pack to drain. After 5 minutes, a Driver Information Center (DIC) message will appear requesting the driver to “Shift to Park.” If the message is disregarded, the excessive high voltage battery drain may require the high voltage battery pack to be replaced.


High Voltage Battery Pack Replacement


If the high voltage battery pack is drained, other DTCs may indicate an issue with the engine or transmission. Diagnose those DTCs first and make any necessary repairs. Also check the fuel level and fuel quality.


After repairing the condition causing the engine to not start and produce torque, the high voltage battery pack must be replaced in order to try another crank attempt. DTC P0AFA also may be caused by an internal fault in the high voltage battery pack. This condition also requires the high voltage battery pack to be replaced. Follow the instructions in PIC6194 to obtain a replacement battery pack, which is currently on restriction.


TIP: The engine will have a limited number of crank attempts when a new high voltage battery pack is installed. There is currently no method to charge the high voltage battery pack other than running the engine.


– Thanks to Lane Rezek and Keith Newbury


The Results are In — Service Information Offers New Search Functions

Enter a few keywords in the Search box of the Service Information, click the Search button, and the results may surprise you. New search functions now offer several ways for you to narrow down a search result, delivering better, more accurate results of what you’re looking for.


TIP: These new features apply to all areas of the Service Information where the Search function is available.


VIN Search


Enter a 17-digit VIN to get search results for a specific vehicle. Up to 10 VINs will now be stored to make it easier to recall information for a VIN that was entered previously. (Fig. 4)



Fig. 4


Basic or Advanced Search


A Basic or Advanced Search can be performed by selecting Basic Search or Advanced Search in the top left corner of the page. A Basic Search returns all Service Information documents related to the model that include the keywords entered in the Search box. For example, “wheel speed sensor” returns results for “sensor,” “speed” and “wheel.” (Fig. 5)



Fig. 5


An Advanced Search will use the keywords as a phrase and only returns results for that phrase, e.g., “wheel speed sensor.” An Advanced Search for “wheel speed sensor” for a 2016 Buick Cascada narrows the search results from 66 to 25. (Fig. 6)



Fig. 6


Snippets of Results


The results from a search include Bulletins, Campaigns and Preliminary Information as well as Service Manual results. Depending on the number of results, they all may not be shown. The first 50 results will appear based on their relevance score. Click Show All Results at the top right of the page to see all results.


A new feature of the search results is a “snippet” that can be shown with each result. The snippet is small section of the document information, which can be helpful in determining the content and relevancy of the results. To see the snippet, select the search result Service Category, or to see the snippets for all result, click Expand All at the top right of the page. (Fig. 7)



Fig. 7


Also, the Service Information application will maintain the selection to expand or collapse the section individually.


Added TIS2Web Link


One additional feature included with the latest Service Information enhancements is a new link for TIS2Web added to the Service information home page and the tool bar. (Fig. 8) The new link adds a convenient way to quickly connect to TIS2Web.



Fig. 8


– Thanks to Lisa Scott



Identifying Non-GM Calibrations in Duramax 2.8L Diesel Engines

2016-2017 Colorado and Canyon models and 2017 Express and Savana models are available with the Duramax 2.8L turbocharged diesel engine (RPO LWN). (Fig. 9) Various performance conditions, such as poor drivability, increased emissions, knocking noises, engine damage and black exhaust smoke, may be caused by an aftermarket power-up kit or other aftermarket hardware.


2016 Chevrolet Colorado 2.8L Duramax Turbo Diesel

Fig. 9


Any time an internal engine hard part failure is found, it’s recommended to check for the presence of non-GM (aftermarket) calibrations. The use of parts, control module calibrations, software modifications, or other alterations not issued through GM will void the warranty coverage for those components damaged by the installation of the non-GM calibration or alteration.


Create a Report in GDS 2


If a non-GM calibration is found, a GDS 2 screen shot is required by the Calibration Group. To take the appropriate screen shot, navigate to Module Diagnostics > Engine Control Module > Identification Information > Calibration History.


Depending on the computer screen configuration and the Number of Calibration History Events Stored, it may be necessary to take two screen shots in order to retrieve, save and view all of the needed information. The report should include the VIN, Calibration History, Calibration Verification Number History and other associated parameters. The VIN must appear on the same screen as the calibration numbers.


Create a report by selecting the Create Report button. (Fig. 10) Email the report to the GM Calibration Group. Refer to Bulletin #16-NA-325 for complete information and email instructions.



Fig. 10


– Thanks to Charles Hensley

GM TAC Process Addresses Vehicle Cybersecurity

If a customer comes into a GM dealership with concerns about a cyberattack or hack on their vehicle, the GM Technical Assistance Center (TAC) has a process in place to help address the customer’s concern and collect information about the concern. Some customers may have been directed to take their vehicle to a dealership by a GM Call Center (OnStar, Customer Experience, etc.) after reporting their concern.



Fig. 11


Contact TAC


If a vehicle is presented at your dealership, contact GM TAC for additional information on how to proceed with any vehicle diagnosis.


Dealerships should reassure customers that GM takes cybersecurity very seriously and has devoted substantial resources to address it, and will continue to do so.


Also customers should be advised that GM is not aware of any real-world instances of anyone remotely hacking into a GM vehicle without owner consent. Any examples known to GM were only research demonstrations.


– Thanks to Len Tillard

Fuel Tank Pop Noise

Some 2010-2017 Equinox and Terrain models may have a popping noise coming from the rear of the vehicle shortly after a cold start or EVAP purge event. The sound may be due to the auxiliary fuel pump changing height — it has a spring-loaded leg — in the left side of the fuel tank.


The popping noise condition can be duplicated by commanding a purge and seal on the EVAP system using GDS2. As the vacuum reaches 3 to 5 inches, the popping noise should be heard.


A revised auxiliary fuel pump has been designed to correct the popping noise. However, the part number has not changed. After ordering the auxiliary fuel pump, verify the letters “PPA” are cast into the top of the fuel pump flange. (Fig. 12)



Fig. 12


TIP: The parts catalog list the auxiliary fuel pump (Fig. 13, #1) as “fuel pump auxiliary,” which is the correct part for this repair. Replacing the primary fuel pump (Fig. 13, #2), listed at “fuel pump” in the parts catalog, will not correct the noise condition.


Fig 13

– Thanks to David Rutkowski

3rd Gear Condition on Manual Transmission

Some 2017 Camaro and ATS-V models equipped with a 6-speed transmission (RPO MM6, MG9) and 2017 Corvette models equipped with a 7-speed transmission (RPO MEP, MEK) may hop out of 3rd gear due to a mis-machined gear. These vehicles will have very low mileage or the condition may be noticed during PDI.


To determine if the transmission is operating properly, shift to 1st gear and then 2nd gear as quickly as possible at a low or medium throttle. Next, shift to 3rd gear and release the shift lever, accelerating quickly to a medium or heavy throttle; then decelerate.


If the transmission does not hop out of 3rd gear, shift back to 2nd gear and repeat the shifting and accelerating procedure 10 times. If the transmission does not hop out of 3rd gear, the transmission has the correctly machined gear. (Fig. 14, #1) If the hop out of 3rd gear is verified, there is a mis-machined gear (Fig. 14, #2) and the 3rd speed gear, synchronizer and shift collar should be replaced.


Fig 14

– Thanks to Steve Schipansky

Crossed Fuel Injector Harness

A rough idle or misfire may be noticed on some 2014-2017 Encore, 2011-2015 Cruze, 2016 Cruze Limited, 2012-2017 Sonic and 2013-2017 Trax models equipped with the 1.4L 4-cylinder engine (RPO LUJ, LUV). DTC P0300 (Engine Misfire Detected) may be set in the Engine Control Module (ECM).


Inspect the fuel injector control circuit wire colors to the engine controls schematics. (Fig. 15) These connections may be reversed, leading to misfires that may occur only under specific circumstances or RPM ranges, which makes them difficult to diagnose.



Fig. 15


If crossed fuel injector connections are found, also inspect the related harnesses and terminals for signs of damage due to the misrouting.


– Thanks to Ray Haglund

Engineering Information Bulletins and Part Restrictions


Service Know-How

10216.11V – Emerging Issues

November 10, 2016


The latest service topics from Brand Quality and Engineering are reviewed, including an overview of the new 2017 Camaro ZL1 and 1LE models and repairs for poor mobile telephone microphone performance. (Fig. 16)



Fig. 16


To view Emerging Issues seminars:

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

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