Can't connect to 2 PCMs - help!
 

Hey guys,

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.

A tech 2 alone will not program any module by it self. You either need a subscription to ac delco tech connect or a bootleg copy of the TIS2000 software. But the bootleg copy only supports up to around 2007 and possible some early 2008 vehicles.

Take the PCM out and try a bench flash, that will tell you if it's any good.

thanks for confirming that - the PCM is off to a tuner to bench flash and remove VATS. If it's the BCM, I may order a clone tech2 with the TIS2000 software and it looks like I can buy a 3 day membership to the tech site to get the data for flashing whatever I may need.

What vehicle are you working on? How did you conclude the BCM is faulty?

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.

Sounds silly but did you check the fuse or power at the port?

Sig lighter fuse works the obd2 hot in the truck platforms. Check there.

It's a '06 CTS-V. I believe the tech2 will work well still on this platform.

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.

checked IGN relay?

It just might work, I personally have no luck using my Tech 2 as a pass through & mines a genuine HP Tech 2 & Vertronix Candi module.

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.

Thank you - I will ensure those have continuity

Found my issue, one of the grounds on the back of the engine, the wire had broken off the ring terminal.

looks like we have a winner

yeah good continuity and the fuel pump starting turning on for a fraction of a second while testing the ECM fuses with a test light as it provided a little current flow.