PCM not communicating

[stone150]

I'm in the process of rebuilding a family member's 2012 Camaro SS, it is a theft recovery and I dropped the engine/trans out of a 2015 car. I also had to change out the fuse block, pcm, ignition area, and gas pedal as these were stolen or damaged.

We had a company come by to reset the theft modules and they said the PCM is not communicating. the engine harness is slightly different on the 15, but from the wiring diagrams, the main stuff is all the same. my only thought is I some how damaged the fuse block while installing it or I accidentally tried to start the car and it bricked the PCM, but I don't even know if that is a thing.

Any thoughts?

[SSMickey]

First check powers and grounds at the PCM. Is this a car an auto or manual trans. GM has the data lines set up in such a fashion that if a module goes bad or a data line gets broke, you will lose communication with all modules behind the bad one. You need to check and see if you have lost communication with any other modules.

[stone150]

Originally Posted by SSMickey

First check powers and grounds at the PCM. Is this a car an auto or manual trans. GM has the data lines set up in such a fashion that if a module goes bad or a data line gets broke, you will lose communication with all modules behind the bad one. You need to check and see if you have lost communication with any other modules.

The car is an Auto, The 2015 was running when I parked it and pulled the engine a few weeks later.
On the 2012, I'm just not too sure the only thing from inside the car that was touched was the onstar module was removed, gas pedal taken, and the ignition module damaged and ultimately replaced with the 2015 parts. I've worried that the extra pigtail on the 15 engine harness is preventing something from firing up, but based on this thread:

https://www.camaro5.com/forums/showthread.php?t=457304

it sounds like that is for the electric power steering only, which was my assumption all along.
It sounds like at this time there is a connection missing or the PCM has some how gotten damaged in the move.

[SSMickey]

Just looked at the wiring diagram for a 15. The High Speed GM LAN runs through the Power Steering Control Module then to the PCM. Without the PSCM there is a break in the network. That's why you have no communication with the PCM. Best option is to get the correct harness, but you could try jumping the data lines at the PSCM connector and see if you get communication back. The problem is the PSCM is on the High Speed GM LAN and the Chassis High Speed GM LAN.

[SSMickey]

Try this if you want, but I take no responsibility.
All of this is done at the PSCM connector.

jump pins 4 & 9(tan)
jump pins 3 & 8(tan/black)
This is the High Speed GM LAN

jump pins 2 & 7(light blue)
jump pins 1 & 6(dark blue)
This is the Chassis High Speed GM LAN

This leaves pin 5, also light blue, but its a comm enable line, or a wake up signal, so it shouldn't matter.

Hope this , but again, your best solution is to get the correct harness.