Glow Plug Control Module Question

[dodgemason]

Is it possible for the GCPM to not shut down after the 2 minutes and slowly draw down your batteries as you drive since the alternator cant charge as fast as the GCPM is drawing down?

 

[blacksnapon]

Is it possible for the GCPM to not shut down after the 2 minutes and slowly draw down your batteries as you drive since the alternator cant charge as fast as the GCPM is drawing down?

Anything is possible, but I've never run into that. I'd come closer to believing a radio or something else not shutting down.

 

[dodgemason]

I've gotten a code that said something like gpcm communication failure. The tech cleared it and said it might be bad wiring because the itself tested fine. Code came back and I was told not to worry about it unless it was hard to start in cold. Then after a couple of months I went out and when I tried to crank my batteries were dragging for a day when cranking and then went dead. I can't find anything else that's drawing from them

 

[Blue Goose]

Have you tested the alternator? I had an alternator go out where it was putting out enough juice to keep the idiot light from lighting but wouldn't put out enough juice to keep up with all of the electronics etc. it takes to run the engine and truck... The more I drove, the more it drained the batteries...

 

[dodgemason]

I did test the alternator and it tested fine. I've gone through the week and the check engine light has come on and gone back off on several occasions. This makes me wonder if I've got some kind of wiring issue

 

[blacksnapon]

You might check pin fit on each connector terminal.

 

[jebadiah04]

It's possible for the relays to actually stick in the on position. They have a powered coil ton push them in but rely on a light spring to pull them back. It is very possible for the relays to be doing that especially in the cold weather. I've seen it happen on other relays.

 

[dodgemason]

Now the engine light comes on for a few days then goes off. Also notice that when the light is on my batteries drain. Wonder if it's the module or bad wiring

 

[blacksnapon]

If its the same dtc, diagnostic circuit tests are in order to determine if its a wiring or module problem.

 

[dodgemason]

i had my batteries tested and both failed. installed two new batteries pulled the hrnesses off the gpcm and cleaned them and the light went off. havent had a problem till this weekend. I was on a long trip and my degas bottle puked coolant everywhere. Now the lights back on. could the coolant have affected the harness below where it goes to each glow plug?