I have been having really hard starts at under 40 degrees. I took truck to dealer to have diag done (100 bucks). They said all 4 glow plugs read 0 on the drivers side and are bad. Of course they gave me a repair estimate of 900 bucks to fix it. I told them ill look into it. So I was wondering how all on one side can go and none on the pass side. I have read about the GPCM going bad as well. I just installed 2 new batteries (motorcraft 850's) and a new stancor GPR last week. They batteries were due anyways. Is there a way to check the GPCM? Ill get another one if thats the case. Truck has thrown any codes or does it throw one if it is bad? any help would be great. thanks jeff

I think i just read that 7.3 does not have a GPCM only the relay which i know is working. any other ideas ?

 

The relay controls all of glowplugs. It is easily testable by putting a volt meter on the side closest to the drivers side, when you turn the key on it should have 12 volts for 10-15 seconds. If that checks out, take the valve cover off the drivers side take the wire off the glowplugs and put a test light from hit post to top of plug, if it lights up its good if not its bad. I think 01 up 7.3s had some sort of gp controller 00 back were controlled by the pcm but I'm not sure about that.

 

You will not have both a GPCM and a GPR. You have a F350, so is your truck a "California" truck? If you have 2 of the relays that look alike on the passenger side head next to the valley, you DO NOT have a GPCM (AIH and GPR relays). The GPCM sits where the second relay would be (GPR), and it is an aluminum square with two large plugs coming off it on the valley side. One plug is green, the other is brown. If you have a GPCM, it will throw a code quick if GPs are bad on either bank. A GPR does not throw a code.

 

What Mike posted.

Here's a pic:


Stewart

 

Yes thats for the replys, I do have the GPR, which I just replace a few weeks ago with the Stancor. Im 90 % sure now that my connector is melted under the valve cover causing the dead glowplugs. I am ordering the parts now for the job, here is what im ordering... (zd-11 motorcraft) 4 glow plugs, 1 set CCV viton o rings (MC), 1 valve cover gasket (MC), 1 undervalve cover harness (MC). I dont believe i need any more parts but anyone has done it please let me know. I will order later today from Riff Raff. All are Motorcraft parts so hopefully i wont need to go back into it. thanks Jeff

 

Sad part is, the dealership (during their $100 inspection) likely found that out and didn't tell you exactly what was wrong. That is how some of them do things...

 

Zero what... ohms? Many meters will read the glow plugs as zero ohms, which begs the question - what do the passenger-side glow plugs read?

Before ordering a whole bunch of parts and turning a few wrenches, I would get my hands on a multimeter and learn what I can about what's really going on in there.