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I have a 2001 Ford Excursion 7.3 diesel. My service engine soon light came on about a month ago 400 miles. The other day I was on the interstate doing about 70mph and it started to shake and run rough. When I would back off the pedel it would smooth out a little but it still was running bad, it was loosing power and I just made it home. So the next morning when I went to start it, it continue to run rough and blow out white smoke. Finally after starting it a couple of times it wouldn't start at all. Had to tow it to the dealer and they said it was the fuel pump. They replaced the fuel pump and I drove it home about 20 miles. The next day the service engine soon light came on again. Took it to autozone they said it is throwing the following codes--- PO672/PO6743/PO676/PO678. This means something is wrong with the glow plug circuit #2#4#6#8 all on the drivers side. Could a faulty glow plug module do this and if not can someone tell me what it might be.
Thanks Bill.
How is the truck running now with the SES light on? If the truck is running good, then yes, I'd suspect the controller. Try getting the codes cleared, swap the connectors, and see if the codes don't show up for the other side of the motor (1,3,5,7).
If the engine is running rough, then I'd suspect a loose wiring plug under the valve cover (UVCH)
Well' I swaped the connectors and went back to autozone. They pull another code PO683 which means ECM has detected a communication fault with the glow plug module circuit. So I will swaped back to the begining and go back to pull another code. Are you sure the two connectors are interchangeable they look the same just one is black and one is green. I'm thinking the color is only for right or left bank.
I swaped the connectors back to the begining and the service engine light won't come on. Maybe its fixed! or maybe it need to be a cold start. Anyway I'll wait till tomorrow morning and see.
No, they're not interchangeable, but as you've discovered, swapping the plugs for a little bit is a useful diagnostic tool.
Odds are, your CEL will come back on soon enough, and the codes will be similar to the last time. Unless you're lucky enough to just have had a loose connector on the GPCM, it sounds like you'll soon be needing a new controller.
Hey F350, I think it's the controller too, I guess I'll keep driving it till the ses comes back on. Right now its running great, we will see how hard it is to start tomorrow, I wished that when I swapped the connectors the 1 3 5 7 would have showed a code, Because if it is the controller it's not so hard to change out. I don't know if I want to tackle the glow plugs if that what it turns out to be. If you remember when this first started the truck had to be towed to the dealer because it would'nt start. They said it needed a fuel pump, so they replace it, and that did the trick. I think that they should had picked up five codes, what do you think? My SES light was on a long time before it finally quit on me.
I am going to second the GPCM. There seems to be a rash of them going out lately. You are the third Ex owner in 4 weeks. Partsguyed has them for about $122.
You can check the glow plugs with an ohm meter. On the inboard side of the drivers head you'll see a long plastic connector. Unplug this and you will see 9 flat pins inside there. Place one lead of your meter against a good ground, and then ohm the front 2 and back 2 pins at the valve cover connector. A good glow plug will have a reading of less than 2 ohms.
Hey guys, SES light came on this morning, so I went to the dealer and got a GPCM and change it. We will see if this is going to fix the problem, have to wait till morning when its cool. I thought you could run a test with the ohm meter, but did'nt know how.
Well, Went out this morning to start my excursion and the service engine soon light did not come on. I think it's fixed, looks like it was the glow plug control, will find out for sure in due time. Special thanks to Chris and duck fan for the imput.
Bill.