How to fix GM Corvette C6 BCM or ECM problems?
I cut the wires going to the XM Satellite Radio module in the trunk. I was trying to wire in a aux input. Yes I had the battery still hooked up. First sentence. After putting it all back together to test, I noticed a red blinking light on radio. I have not seen it before. I had just bought this 2007 base 3LT. A week earlier. This is my 3rd Vette to own. 1989 and 2001 were my others. I tried to crank car and got a clicking sound. No lights on dic either. I had both doors open, windows down and rear hatch open so I thought I ran battery dead. Charged it and nothing still. Light on door is red when I try to open it but it won’t open. So I reach in and pull emergency lever to gain entry. I put key in glove box slot and still no crank. I can hear the RCDLR make clicking sounds. No blown fuses relays. I towed to the only gm dealership within 100 miles. They don’t have anyone who knows vettes. The mechanic is ready to scream. We hooked up tech 2 and it shows no codes. It says no communication with ECM. The OSB port under dash only has power when every few minutes I hit the start button. We thought I unprogrammed keys so was gonna reprogram RCDLR. Can’t communicate with it so he says bad BCM. Purchased a BCM and same thing. Can’t communicate with it or RCDLR. He hooks computer up to tech 2 and car with the Chevy software and same thing can’t communicate. So he says ECM. Put that in car and same thing no communication. I said program ECM with vin then install it. He said they don’t have a way or adapter to do that. He said he didn’t program BCM either because they do it after install with computer. He has no other ideas of what to do. Like I said no dic on dashboard. Been over 2 weeks now and I’m so frustrated. Need help bad. Would a ECM I bought programmed already with my vin bring dic back to life? BCM? I know the wires I cut was power ground audio and serial data class 2 wire. I repaired the wires solder and heat shrink wrap.
Sounds like you still have the serial bus shorted. Try disconnecting the digital radio receiver at the star connectors.
C6 is a little different than the C5. It still has the C5 style Class 2 datalink but the major controllers are connected on the high speed GMLAN. The BCM is the module where these two controller networks come together.
Here are the schematics from an 08 which should be very similar for 05 through 12:
Manual Transmission High Speed GMLAN
Automatic Transmission High Speed GMLAN
Power/Ground and Class 2 Datalink Schematic:
Heck, you can disconnect almost everything. I think you only need the VCM and BCM to get communications with the ECM to work. For the car to run you might also need the RCDLR. So you could disconnect the star jumpers and just jumper wire those 2 or 3 modules. I'd try the BCM and VCM first and see if the GM TECH2 can see the BCM and ECM then add more in and ensure the TECH2 can still communicate with the modules added.
I doubt it's the ECM or BCM. The dealer is just wasting YOUR money learning how to properly troubleshoot this type of issue.