Main computer cannot communicate with the transmission computer

2009 CHEVROLET HHR
130,000 MILES • 2.2L • 4 CYL • 2WD • AUTOMATIC
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STEPHEN KELLY
  • MEMBER
  • 1 POST
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.
May 11, 2021 at 1:32 PM
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JACOBANDNICKOLAS
  • ✓ASE Certified Mechanic
  • 110,194 POSTS
  • ASE Certified Mechanic
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
May 12, 2021 at 8:42 PM
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