Electrical Problem

[camobronco]

Summary: explanantion of diagnosis for rough idle and no power, which got worse over a day. key words: IDM, uvch, vcg, glow plugs, injectors, CPS.

Long, but a good read.

This is told about my 1995 F350 CC LB with DIY intake, straight exhaust and no other mods.

Here is my situation, I tell it to maybe one day help someone else:
On a Friday afternoon driving my truck around, suddendly my truck lost any pulling power. It was still running, but barely. Plus I had the dreaded CEL during this. It did this for about thirty seconds, then picked back up and ran fine. My next trip out the same day it happened again, this time twice. I limped it back home. While at home I was moving the truck around the yard, was running fine, then same issue, but this time I was at idle. So, I realized that it could barely run at idle. At this point it never made it back to running good.

I got on my favorite website (powerstroke.org) and started researching. I do not have a code reader and it was undrivable. First diagnosis was CPS (Cam position sensor). I picked one up from O'reilly's, just hoping this would fix it. NOPE!!!. Back to my favorite website. Well, at this point I used the trusty multimeter to start checking resistence on the vcg harness and uvch. Whle checking these I realized that two vehicle harness side plugs were melted on the glow plug wires (one on the passenger front and other on the driver rear), but all the resistance still read correctly. While checking these I realized that only the drivers bank of injectors was functioning. That is when I started to suspect the IDM. I came across this document. http://www.ford-trucks.com/forums/at...chmentid=47977 which allowed me to check all the wires from the harness plug at the IDM. While following steps on this sheet I failed one of the test, which led me to the passenger side vcg at the front plug. I had already checked the resistance, but I did not check to see if they were grounded. I check each of the five against the chassis ground and they all were grounded. At this point I took off the valve cover and checked the passenger front uvch, which checked out fine. The problem was a short in the valve cover itself.

My plan is to replace the two melted vehicle side harness plugs and both valve cover gaskets. I just hope that this issue didn't take out the IDM.

I would like to ask a question: should I go ahead and replace any of the uvch, or other vehicle side harness plugs that are not melted, or glow plugs?

Will update when back running.

[Patrick Feeley]

If any of the pins in the gasket were torched, I would change the UVCH (or external plug), depending on which side of the gasket pin(s) were scorched. Cheers!

[camobronco]

I found a valcve cover gasket kit from O'relly's for 64.99/ea. This kit included the valve cover, uvch, and repair pigtail for vehicle harness side. I went ahead and ordered two. Still trying to decide if I want to change my glow plugs and am hoping my IDM isn't fried.

[madpogue]

If it's running at all, the IDM is _probably_ okay. Even if it's not starting, if it ran (even badly) until you shut it off, and simply won't restart, you may still be out of the woods wrt. the IDM. Esp. if you see any white smoke while cranking.

Are those gaskets/harnesses the Dorman brand, by any chance? They don't have the best reputation. No doubt better than the toasted parts you have now, but they've been known to short out and/or fail. One guy even had one short to ground only when he tightened (to spec) down the valve cover; drove him crazy 'til he actually saw the ohmmeter respond as he turned the wrench....

[camobronco]

It does run, and no white smoke.

They are dorman brand. I have heard mixed reviews, but that goes with about any parts you order. Oh well, already on order. Will let you know how they do.

[camobronco]

Got it fixed. The passenger side was the problem side, but I went ahead and replaced both sides. Cranks faster, idles better, and runs amazing well. I am glad it didn't take out the IDM. Total project from initial finding to parts install took 4 days and ~$165.

Thank you powerstroke.org