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Glow plug control module
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Mountain Pass
Joined: Jun 2006
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Glow plug control module
It's in a 2000 Excursion. I pulled the codes p0672,p0674,p0676, p0678. First I pulled the valve cover and checked the wire harness. All looked good and I added a quarter while I was there. Then I checked for continutiy between the black plugs at the conlrol module to the plug that goes into the valve cover. Good there also. I checked for resistence from the pins at the valve cover plug and was good there. I find it hard to believe that all the left bank glow plugs would go bad at once especially since I am getting such low resistance readings suggesting good plugs. Is there any way that the control module could go bad just on one side? Is there any way to test it? Any other places to look before I spend $200 bucks for a new module? Thanks everyone.
Post Fiend
Joined: Nov 2007
Posts: 9,549
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From: Payson, AZ
Half the GPCM can go bad. To test this swap the two connectors and see if you get the same codes. If the same codes come up the GPCM is bad. In all instances I have heard of when you get GP codes for all one bank it has always been the GPCM.
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Mountain Pass
Joined: Jun 2006
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Thanks. In the TSB it said not to swap the plugs. I figured it was because the module plugs not only go to the glow plugs but also commmunicate with the pcm. I guess it is time to lay down some cash.
Post Fiend
Joined: Nov 2007
Posts: 9,549
Likes: 14
From: Payson, AZ
They say not to swap the plugs because if a GP went bad it would give a code for the wrong GP, the corresponding one in the opposite head. But swapping them won't hurt anything, just be sure to swap them back.
Because racetruck
Joined: Apr 2007
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From: Monterey Bay, CA
Thread Starter
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Mountain Pass
Joined: Jun 2006
Posts: 197
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Yea, and it is a non-catalyized non-California station wagon. Guess they put them in all Excursions. Thanks duck fan for the link. I don't know if I can wait for shipping up here. That and the extra cost of shipping fed ex and I can probably match the cost at a parts store. With some discounts of course. Thanks everyone. I will let you know if replacing the module fixes the problem. I am now confident it will.
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Because racetruck
Joined: Apr 2007
Posts: 2,786
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From: Monterey Bay, CA
If the GPCM goes bad there are a few things it can do. There is a specific module code or it can throw codes for the even GPs or odd numbered ones.
The advantage to the GPCM is if one GP goes bad, you will set an SES light for just that one making replacement easier.
The advantage to the GPCM is if one GP goes bad, you will set an SES light for just that one making replacement easier.
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Mountain Pass
Joined: Jun 2006
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Update
Here is an update for those who care. I put the new GPCM in last night. Started the truck last night and this morning. It didn't throw anymore codes and started like all glow plugs were working (even though it was kinda warm this morning.) Looks like it did the trick. Thanks to all.
Cross-Country
Joined: Jun 2007
Posts: 96
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From: Just outside Chicago, IL
I realize I am posting a year later, but my Ex is starting hard in the cold. Are you guys SURE you get a SES light if the GPCM is bad? I get no SES lights, just hard starts.
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When you say starting hard do you mean long cranking or white smoke after start up?
Post Fiend
Joined: Nov 2007
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From: Payson, AZ
Of course the best thing to do would be to pull the codes.
Cross-Country
Joined: Jun 2007
Posts: 96
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From: Just outside Chicago, IL
Thanks for the fast replies guys!
When I say hard start, I do get great cranking (good batteries and white smoke), it usually takes a few tries before it will turn over and then it runs rough for a couple of minutes at about 1000 RPM. Then all seems okay. It's just the initial start that is tough in the cold. I hear the usual whoooosh of the cold air intake heater kick in FWIW, each time I key on. It seems to do that even in the warm weather too.
I will try disconnecting the GPCM connectors, one at a time and even swapping them. I have a code reader so I can see what that gives me. Current price for a new GPCM at that "Parts Guy Ed" is $124 which isn't bad if that fixes my situation.
Thanks to all......time to go out and see what happens!!
When I say hard start, I do get great cranking (good batteries and white smoke), it usually takes a few tries before it will turn over and then it runs rough for a couple of minutes at about 1000 RPM. Then all seems okay. It's just the initial start that is tough in the cold. I hear the usual whoooosh of the cold air intake heater kick in FWIW, each time I key on. It seems to do that even in the warm weather too.
I will try disconnecting the GPCM connectors, one at a time and even swapping them. I have a code reader so I can see what that gives me. Current price for a new GPCM at that "Parts Guy Ed" is $124 which isn't bad if that fixes my situation.
Thanks to all......time to go out and see what happens!!