Where can I check the ground for pcm, it appears its not grounding my gpr, can I manually ground my relay and leave it that way or is there a ground on the pcm I can check?

 

The PCM only grounds the GPR when the oil temp is cold. The ground is the aft small post on the GPR. If you are checking it with a volt meter or a test light it will show power as it is attached to the coil on the GPR. You can simply apply a ground to it for testing to check the GPR.

Have you verified the GPR is working properly? Usually they are the fail point.

The ground wire out of the PCM for the GPR is pin 101 on the 2002 trucks. Should be similar or close on the other ones. Look for the violet/orange wire.

 

which of the small posts do I ground to check if the relay is working? the one with the red wire?

I'll just rig up a wire and attach it to the battery ground then connect it to whichever of the small posts

 

by the way thanks for quick help I'm kind of freaking out because its starting to get cold here haha

 

GPR Operation

 

please disregard this thread and go to this one

https://www.ford-trucks.com/forums/1...l#post10867068

sorry for confusion

 

When putting in a replacement ECM, can I test it without mounting it to the firewall?

 

In theory, yes, but in practice... the 104 pin wiring harness at the firewall isn't long enough to place and support the PCM anywhere else but where it is supposed to go.

I have run a PCM in this application unmounted, with the PCM laying on the floor where the center "20" seat or console would normally go, but to make that happen I had a 104 pin extension harness, in the form of a break out box.

The PCM has multiple ground pins, and is grounded through the 104 pin harness, even if the metal case of the PCM is not in contact with any metal spring tab on the mounting cradle screw.