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Hey y’all, I’ve been trying to resolve a CEL that throws off P0683 - “GPCM 1 - to PCM Communication Circuit”. Engine runs fine, but clearing the CEL only works for 1-2 starts.
I got under the hood and inspected the GPCM. I’m not the original owner and it definitely looks like this has been messed with years ago. On the black wiring plug, I found pin 3 to be burned up a bit on both the male and female part of the connection. See photos. I cleaned up the connection and put it all back together to see if that would work. Couple of starts later, it’s throwing off that CEL again. And I actually had the engine stutter a couple of times (lighting up the glow plug light and some other fuel light in the dash for about 5 seconds).
Should I replace the GPCM? Or the pigtail with the black plug? Or that entire wiring harness for that bank of cylinders? The replacement wiring plug is about $70. The new GPCM plus wiring harness is around $300. The latter option seems like it would 100% solve the problem but also looks like it would be a total PITA to do since it’s difficult to reach each cylinder.
There’s some char visible on that long, top, center pin Pin 3 is burned up
If it was me I would replace the entire harness. With the burnt pins, you’ll most likely find some corrosion and blackening of the individual wires. This may compromise the new connectors if you chose to go that route. Yes it’s a pain in the ***, but in my opinion a much better repair.
After talking it over with Prosource Diesel, I realized that I actually need to do both. The glow plug wiring harness connects into a different wiring pigtail that wires into the GPCM. So I’ve got the entire kit on order.
has anyone done this? I’ve found a few YouTube’s on replacing the glow plugs and GPCM. If you’ve got any handy tips or tricks, that’d be appreciated.
Ford does sell a connector repair kit. What I would do is unpin the good wires and plug those into the new connector and then splice the bad wire to the enew wires. Every splice is done with a non insulated connector and covered with shrink tube. Usually there is only one bad wire, so one splice.
Ford does sell a connector repair kit. What I would do is unpin the good wires and plug those into the new connector and then splice the bad wire to the enew wires. Every splice is done with a non insulated connector and covered with shrink tube. Usually there is only one bad wire, so one splice.
I’ve got this AND the harness kit coming. Was planning to try the connectors first. In my 2-minute inspection I didn’t see anything wrong with the wiring but once removed from the connector I should be able to fan them out better. I’ve got a new GPCM coming also but I have no reason to believe anything is wrong with the one that is in there.
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