Hi everyone,
I wanted to see if anyone can provide some input with a problem I'm currently experiencing with my new Hybrid Silverado 4wd 2009.

A couple of weeks ago I noticed that my check engine light was on and decided to take it to a dealership to get an electronic scan. Even though this car is new and only has about 1000 miles of usage here's what appeared in the scanner:


P0AC4: Hybrid Powertrain Control Module Requested MIL Illumination
P0690: Control Module Power Relay Feedback Circuit High Voltage
P0442: EVAP System Small Leak
P0C32: Hybrid Battery Cooling System Performance
P2797:Auxilary Transmission Fluid Pump Circuit Performance

Of all these, they mentioned, the only current problem was the first one "P0AC4" since all the other ones were historical records.

What they did they? They erased everything and only "P0AC4" came back.
Whenever I drive the vehicle I can feel the car not functioning as a hybrid and I've noticed a sharp increase with gas consumption.

....Now the biggest problem here is that I brought the car to South America, and even though there is a big GM dealership, I don't trust their knowledge on Hybrids .

If anybody has any knowledge about this issue or decent suggestions please provide any input.

Regards,
Dave

 

The battery cooling performance... did you have blankets or coats on the floor in front of the back seat possibly blocking off air flow? Aftermarket mats?

The P0AC4 has a reason. The P2797 may be it. Have the dealer look for Technical Service publications regarding the Auxillary Transmission Pump.

 

Thank you for your reply, Marty.

What they said they would try was a firmware update. They said that could fix everything, and that is precisely what worries me, they are just training the staff here about hybrids.
I really hope I don't have to ship the car back to the US only for some minor issue.

 

all the system of the hybrid relies on the ecu that any changes, updates needs to be reflashed to the ecu. what the local dealer can do is upload the updates and reflash your ecu to correct your problem.

 

just like everything that is computerized today. If it acts up, reboot it first, then go forward. Good luck, we have the same truck. I love mine, I don't think you will have to ship it back. If they are a GM dealership, they can be trained!

 

In addtion to what Hillibilly said, in general it looks like someone didn't clear codes after doing some service work...

Although you won't know until spring in New York if the Evap Small Leak fault is truly fixed. Evap tests don't run much in the winter.

 

I really appreciate all of your input, but as you may imagine I love the truck
and to have this happen so soon has me pretty worried, particularly seeing the electric motor not kicking in, like when rolling softly at slow speed.
I wasn't careful at the time of purchase, I forgot to have it scanned or inspected properly. Aside from these issues they also sent it with some defects on the right rear door, like a lock **** missing and the broken plastic thing that runs on the bottom-outer edge of the window (I don't know the exact name of the part) as well as a missing manual. Thank you again, I just wish P0AC4 were more explicit.

 

doesn't go in to elec mode till it is at operating temp. and thats a problem as it is cold where I live and it often doesnt even open the thermostat on short drives. My mileage is suffering.....dang global warming...er uh....

 

Jet 1 does the 10min remote start help at all on the warm up issue. All my drives are long so I have not experienced this except the decrease in MPG during the cold weather. At the start of fall/winter we are used to always using the remote start.

 

delasierradh is not in New York. He said he took the truck to South America (southern hemisphere). It is summer there and his temperatures, depending on where he is could be very warm or at least mild. So the cold warm up may be little factor there.