Friend of mine picked up a 2002 7.3 CC LB F250. He suddenly got the the check engine light and when we scanned for codes we got the P0670 and the P0683.

We did some research and everything points to the GPCM since this is a California vehicle.

Since my Ex is the same year we decided to swap the GPCM's between trucks but the SES light did not go out.

My Questions....
1. should we have driven the truck for a certain amount of time after the swap for the SES light to go out?
2. Do we need to clear the codes after the swap then drive it around to see if the light comes back on?

We didn't have enought time to drive it around after the swap but left it running for a bit to see if it would go out.

Tim M

 

There is most probably a circuit problem and not a mechanical issue. Somewhere along the circuit it is open or has increased resistance and the PCM is reporting that as out of range.

Try removing the PCM Harness and cleaning it with CONTACT CLEANER and do the same at every point up to and including the GPM.

In the process, you can use a VOM to check the continuity of the circuit.

 

Simply swapping the GPCM won't clear the codes. Get a code reader, clear the codes and see if they come back with the new GPCM. Or disconnect the batteries for a few minutes.

 

I had to put mine back in because I needed the truck. I should have more time to swap it again and ill clear the codes this time.
Ill have him take it for a bit of a drive and hope the code doesn't come back.
Tim M

 

Ok, my buddy is working till 5:00 today and so our goal is going to swap the GPCM again, double check the connections, clear the codes, and go for a joy ride and hope the check engine light does not return.


Thanks guys for the help so far.

Tim M

 

Update....

We swapped the GPCM and cleared the codes and he drove it around up to today without the engine light coming on.
He was able to get his smog check done so he will return my GPCM and pick up a new one for himself.

Lesson learned ...clear the codes or disconnect the batteries. I won't assume the code will clear up on its own next time.

Thanks guys.

Tim M

 

Glad you got it sorted out.