Do you think i have a bad GPCM??

[craig031600]

Ok, a week or so ago i finished my head gaskets (cab removal). I also replaced all the glow plugs (Motorcraft) and both harnesses since i had the truck apart. The day after i finished the head gasket job the truck threw a P0676 code (cylinder 6 glow plug circuit failure). I cleared the code and it just comes back. I swapped the 2 connectors on the GPCM and threw a code P0683 (GPCM to PCM communication circuit). I then put the two connectors back to normal on the GPCM, cleared the code and now its throwing the first one again. Do you guys think i might have a faulty GPCM since i have all new glow plugs and glow plug harnesses???

[sinner6.0L]

possible one of the harnesses isn't seated all the way? they can be tough to push in sometimes.

Start with a resistance check at the glow plug harness connectors. A good glowplug should be around 2 ohms to ground

[craig031600]

Thanks man. I'll check that this week. It starts and round fine, just have that code coming up. Hopefully that's it. If the plug is seated on the glow plug would that mean I could have a faulty GPCM?

[craig031600]

ok, so last night i disconnected the black harness on the GPCM (for the even numbered cylinders) and did an ohm test. All glow plugs tested right at 1 ohm. Before this i pushed down on the glow plug connectorr, the angle my arm was at i couldnt tell if any of them pushed in any. I cleared the check engine light, if it comes back with a GP code, could i suspect the GPCM is faulty?