New to Forum. 2008 3.5 AWD VUE, 104,000 miles, complete 100,000 maintenance service performed plus engine front and rear seals, new starter/alternator/battery, throttle body, engine wiring harness, NYS Emission and Safety inspection. Have had the vehicle about 4000 miles. Strong engine, smooth and positive shifting, excellent gas mileage.

Intermittent issue has happened about 5 times since ownership. Service engine, low power mode, traction control, stability control trouble lights flash then go on steady. Car looses power, runs erratically, shuts down. Ignition is shut off, car rested about 5 minutes, then starts and runs normally with service engine light remaining on. On future start-ups normal start and running with all trouble lights off.

Diagnosis attempts- No codes have show- present or pending. Local shop unable to duplicate problem. Drove and ran diagnostics for several weeks. Car brought to local Chevrolet dealer. No codes present or pending. Unable to duplicate issue after a week of driving. Cars history shows several services for run ability starting at about 25,000 miles. No details (Carfax report).

With the failure to duplicate and diagnose from the local shop and Chevy dealer (both very well known and respected), I am thinking of replacing the PCM. I am concerned that there are no codes stored even with the service engine and other trouble lights triggered on 5 separate occasions. To me, the symptoms indicate a possible intermittent fault in the PCM. Does this sound reasonable? Any other ideas?

 

you need a full featured scanner that reads more than just the p codes.

You also must read the codes when the service engine soon light is on. This should give you the associated p codes as well as any body codes, chassis codes and communication codes. I'm guessing the other codes don't set unless whatever p code is triggering the service engine soon light is thrown. Just a hunch.

The shops are reading no codes because the service engine light is not on when they have it.

I suspect a manufacturer's code or body control module code is to blame. Possibly a communications code. Usually when stabilitrak craps out, it takes traction control with it and vice versa because they depend on the same sensors for proper operation.

Depending on the severity of the problem, or what the car thinks is the problem, it will automatically go into limp mode which is the loss of power and all the other unsavory behavior.

Go to NHTSA.Gov and type in your VIN to ensure there are no outstanding recalls. It is illegal to sell a vehicle with out standing recalls, but putting that aside, if there is something that has not been addressed, it obviously needs to be.

Also, take the time to go through all of the technical service bulletins TSBs that also come up as a separate tab when you search your VIN.

These are critical documents circulated by GM about common problems that have been seen and how to address solving them. They are issued and provided to the techs in the dealerships.

There is no point throwing parts at the vehicle, as it is the equivalent of throwing darts while drunk. Well in your case maybe informed drunk darts.

The problem you describe is not uncommon for that vehicle. The engine was used across several vehicles in the GM line. I simply don't remember the nature of the issue, and it will be very instructive for you to read the tsbs and learn what types of problems your vehicle might, emphasis on might, develop.

Please let us know the resolution. It's not that I don't want to help, but I believe there are multiple causes and therefore multiple solutions, and I don't want to mislead you in one direction or the other.

Feel free to ask any questions about anything. You are most definitely welcome here.

 

Thanks so much for your quick reply, Derf! There has been a lot of frustration with this issue as the VUE is loaned to my daughter who lives 600 miles from me in rural Maine. When the car sets the codes, she is usually loaded with the granddaughters a long distance from home. With the stress of possibly being stranded, waiting a few minutes and restarting restores normal operation (for about a month) until it happens again. Once, when it was closer to home and the local shop I told her to leave it, wait for a tow, and reached her mother-in-law to pick her and the kids up. When the VUE got to the shop they turned on the ignition to read the codes and nothing showed. The car started right up and ran normally. The Chevy dealer (an hour from her) has the GM equipment to do a full scan, but again nothing showed. They had their mechanics drive it home and to work daily with a portable scanner but the car ran perfectly. I am surprised that the cars computer system does not store codes in a history file like my other GM cars and those I work on (Northstar Cadillacs of the early 90's). That makes diagnosis so much easier as the code does not need to be current to show. Some of the diagnosis information I have read does mention stored code data. I have not been able to schedule a trip to Maine to use my code reader, and with the intermittent nature of the problem it is unlikely that I would be there to run the codes when the car is running and they are set. About the only thing I can do is to determine most likely causes, bring parts, and do replacements. The labor charges at the local shop and Chevy dealer are not affordable for more work.

The car has no unprepared recalls. I went through the TSB's prior to purchasing the car and do not remember an intermittent issue like this vehicle is showing. There were a few cases of PCM connection issues and PCM replacements, BCM replacement, etc. but in those cases the problems were constant, and codes were identified.

My daughter and the kids love this car as its size and interior space are perfect for child safety seats, it gets good mileage, performs well (mostly), and the AWD is great for their rural location. I am hoping that I can come up with some most likely causes so the reliability can be returned.