Main computer cannot communicate with the transmission computer

STEPHEN KELLY

MEMBER
2009 CHEVROLET HHR
2.2L
4 CYL
2WD
AUTOMATIC
130,000 MILES

Friday I drove the car with no problems. Saturday I didn't use it. Sunday it had no power at all. Towed to a shop. The main computer was blown. It was replaced and set up by the dealership. It would not communicate with the transmission. The diagnostic hooked under the dash could communicate with the transmission. They worked on it in their spare time for 6 weeks, checking the wires, plugs and pins with no luck finding a problem.

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,885 POSTS

Hi,

This sounds like an issue within the can-bus system. CAN stands for controller area network. Basically, all modules/computers are tied together via a few wires. I would like to think a dealership scanned the can, but anything is possible.

Take a look through this quick video showing how it's done:

https://youtu.be/InIlnsjOVFA

This type of scan should identify a breakdown in any of the modules you mentioned. If it has already been done, let me know what codes were found. If it hasn't been done, I recommend starting there.

Let me know.

Joe