Can't connect to 2 PCMs - help!
Car cranked fine 2 weeks prior. Been finishing my LSA build on the V1 and no further work or wiring was done in the meanwhile. Tuner came over to put a base tune on with HPtuners. He was never able to connect. While connected to the OBD2 port and trying to get a connection the voltage was low - less than 10.5V because my radar detector alarmed. Hooked up a battery charger and voltage stayed in the 12s while we tried another PCM that I had for this car.
Here's the issues - neither pcm will connect to any scanner. both are in theft mode. doing the key relearn does not reset the security lock light on cluster.
Any ideas if I maybe fried the body control module during that initial hookup try? I wonder if that is the common problem?
Thanks, stuck right now and thinking about buying a tech2 clone if I need to buy a BCM as I believe it needs programming.
Take the PCM out and try a bench flash, that will tell you if it's any good.
Take the PCM out and try a bench flash, that will tell you if it's any good.
Using a Tech 2 as a pass through is hit & miss....Mostly miss on vehicles that use CAN, You will most likely need a GM MDI.
Yes the cig and obd2 both have power. I am only suspect of the BCM because I have a backup PCM that has worked for this car and neither will connect to a scanner, both are in theft mode and the key relearn does not work. BCM may be a common problem? I honestly don't know what powers it has on the PCM but I do know it's involved in the theft stuff. All lights and functions work on the car other than the no start condition and theft mode.
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Yes the cig and obd2 both have power. I am only suspect of the BCM because I have a backup PCM that has worked for this car and neither will connect to a scanner, both are in theft mode and the key relearn does not work. BCM may be a common problem? I honestly don't know what powers it has on the PCM but I do know it's involved in the theft stuff. All lights and functions work on the car other than the no start condition and theft mode.
You should be able to communicate with the ECM unless it has a missing power/ground.....OR.....the GMLAN data lines are damaged/shorted.
Your car has a VERY simple GMLAN BUS......
Pin 53 of the C3 ECM Connector is wired to Pin 6 of the DLC Connector. (Tan/Black wire, Negative side of the BUS)
Pin 33 of the C3 ECM Connector is wired to Pin 14 of the DLC Connector. (Tan wire, Positive side of the BUS)
The ECM is the ONLY GMLAN component in your car, Every other module is Class 2 Serial Data.
You should be able to communicate with the ECM unless it has a missing power/ground.....OR.....the GMLAN data lines are damaged/shorted.
Your car has a VERY simple GMLAN BUS......
Pin 53 of the C3 ECM Connector is wired to Pin 6 of the DLC Connector. (Tan/Black wire, Negative side of the BUS)
Pin 33 of the C3 ECM Connector is wired to Pin 14 of the DLC Connector. (Tan wire, Positive side of the BUS)
The ECM is the ONLY GMLAN component in your car, Every other module is Class 2 Serial Data.








