TAC Tips Spring 2018
We are resolving a number of cases every day and wanted to share some of the great conversations and tips we’ve had from across the country. Follow-up on Twitter or Facebook for a regular update.

Contributor: ACDelco’s Weekly TAC Tip comes from the team at ACDelco’s Technical Assistance Centre.

May 29, 2018
Thanks to our program member from:   Middle Sackville, NS
Vehicle: 2015 GMC Sierra 1500 4WD
Condition: Engine cooling fans circuit gives DTCs P0691, P0480 and all troubleshooting leads to the replacement of ECM, but after replacement, it’s still showing the codes.
Agent recommendation:  Check for aftermarket devices installation and confirm if it does have remote starter installed non-OEM.
Solution: Found aftermarket installation was creating interferences with GMLAN high-speed network, even when the device power supply was disconnected.

May 22, 2018 
Thanks to our program member from: 
 Simcoe, ON
Vehicle: 2016 Acura RDX 3.5L
Condition: Parking aid sensor has a code B261F-00 for sensor #4 and if erased, it comes back. The truck just came out of the body shop.
Agent recommendation: Check with troubleshooting procedures for specific DTC.
Solution: When a sensor is replaced, there is a resetting procedure for the parking aid and backup control unit that is available. This was sent to technician and that took care of the problem.

May 15, 2018 
Thanks to our program member from:    Concord, ON
Vehicle: 2009 Chevrolet Malibu Hybrid 2.4L
Condition:  Generator will not charge. Found hybrid battery loose and was corrected but now has code P0AA2 for positive relay stuck open.
Agent recommendation: Check connections according to OEM procedures.
Solution: When the hybrid battery cover is not fully installed, the security switch stays open and the contacting relay for the positive circuit could not be applied. Has secure cover and now the vehicle is working normally and DTC is gone.

May 8, 2018
Thanks to our program member from:    Brampton, ON
Vehicle: 2005 Ford Escape Hybride 2.3L
Condition: Engine started and stalled. DTC codes found P0087, P1235, and P1A0C in ECM.
Agent recommendation: Check fuel pressure with gauge according to recommended procedure.
Solution: After checking the pressure, the fuel pump was replaced and vehicle is now functioning normally.

May 1, 2018 
Thanks to our program member from: 
 Balmoral, NB
Vehicle: 2017 Chevrolet Silverado 2500 HD 6.6L Duramax
Condition: No communication with scan tool for TCM, ABS and no DTCs found.
Agent recommendation: Check all communication networks, specifically the GMLAN high speed for a total resistance of 60 ohms.
Solution: Checked all voltage power supplies to each GMLAN module and found that the trailer brake control module didn’t get the 12 volts power supply. Found that the wire under the floor carpet at the splice pack was corroded. Repaired the wire and now communication is OK.

April 24, 2018 
Thanks to our program member from:   Lashburn, SK
Vehicle: 2014 GMC Yukon Denali
Condition: Vehicle has vibrations when in 6th gear. Feels like it is driving over rumbling strips and when shifting back in 5th gear it’s gone.
Agent recommendation: Check if new updates are available and research for similar cases.
Solution: Technician spoke with transmission specialist and torque converter is defective.

April 17, 2018 
Thanks to our program member from:   Grande Prairie, AB
Vehicle: 2007 GMC Sierra 1500 4WD
Condition: Engine will not start and is not cranking. There is no communication with BCM and has code U0140 in ABS module. Shop has tried a new BCM and SPS programming was saying that the module already has the latest calibration installed.
Agent recommendation:  Check the GMLAN low and high speed, but all symptoms suggest replacing BCM.
Solution: BCM must be replaced again as the one received has already been installed and programmed on another vehicle. It was returned to parts distributor, replaced again with another new one and reprogramming was successful and vehicle work normally.

April 10, 2018 
Thanks to our program member from:    Boisbriand, QC
Vehicle: 2008 GMC Sierra 2500 HD 6.6L Duramax
Condition: Trailer brakes are inoperative (original equipment installation). Trailer brake control module has been changed and same results with no current going to the trailer brakes.
Agent recommendation: Check configuration with BCM for compatibility.
Solution: When a module for trailer brakes is replaced, a trailer must be hooked up and driven in order for the module to see the vehicle speed sensor.

April 3, 2018
Thanks to our Program member from: Guelph, ON
Vehicle: 2010 Chevrolet Traverse
Condition: Engine has misfires on Bank 1 but nothing looks abnormal.
Agent recommendation: After talking with the technician, it was found that the engine had been recently replaced with remanufactured engine from GM. Agent suggested to check the camshaft according to published TSB for REMAN engine and to check for chaffing harness at rear of engine.
Solution: Found the rear engine ground was not tight enough when engine was replaced. Torque ground after cleaning it solved the issue.

March 27, 2018
Thanks to our Program member from: Brownsburg, QC
Vehicle: 2012 Hyundai Elantra
Condition: Crank, no start intermittently, code P1696 in PCM memory.
Agent recommendation: Suggest checking the immobilizer coil around the ignition key for loose or bad contact.
Solution: Replaced the immobilizer coil and reprogrammed the ignition keys. Vehicle is now OK.

March 20, 2018
Thanks to our Program member from: Saguenay, QC
Vehicle: 2006 Buick Rendez-Vous 3.5L
Condition: Defective EGR valve, after replacing it has code for EGR in ECM.
Agent recommendation: Check when an EGR kit is used for modification on the EGR connector. TSB 06-06-04-003D must be applied.
Solution: Checked according to bulletin and modifications were made to connector. Vehicle is now OK with no DTC.

March 13, 2018
Thanks to our Program member from: Perth, ON
Vehicle: 1991 Chevrolet Corvette
Condition: Vehicle is unable to communicate with ECM and BCM intermittently and speedometer is erratic.
Agent recommendation: Check powers and grounds to ECM. Also try a tap test on ECM.
Solution: Tap test on ECM showed communication cutting in and out. Replaced ECM.

March 6, 2018
Thanks to our Program member from: Guelph, ON
Vehicle: 2009 GMC Acadia 3.6 L
Condition: No start and no communication with scanner.
Agent recommendation: Check engine ground on backside of the engine, as it is a known issue.
Solution: Ground bolt was loose.

TAC Information 

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