Hello,

I've been searching here and online for an answer, but haven't found any descriptions of a problem similar to this...

I discovered this problem the other day after running down a rough dirt road with the 4 wheel drive engaged. I was driving down the highway afterwards and noticed the 4wd was still engaged (front driveshaft hum from spinning at highway speeds). I pulled off the hwy at the rest area and started doing some checking around.

The dash switch was in 2wd and the light on the dash was off, the hubs were in the auto position (not manually locked). I checked underneath to see if any of the wiring connections appeared to be disconnected or loose and found nothing. I went back to the cab and discovered that the headlights/radio hadn't shut off automatically, and also discovered the doorlocks weren't working. This led me to the fusebox where I discovered the fuse for the 4wd/security module was blown. I replaced it and thedoor locks / 4wd became operational again. I was able to get into 2wd and make it home. The next morning I discovered my door locks weren't working again, and the fuse was blown again. When I went to replace the fuse it arced in the fusebox and lightly welded the left side (input side) of the fuse in position before blowing it again. I was able to get the fuse out, but after replacing it again the new fuses do not blow, nor do the 4wd and doorlocks work...

I've used a test light and verified that I still have power at that fuse position, but haven't been able to go further with it yet due to a lack of time. I'm going to grab a volt meter and do some checking later today but would like some help with suggestions on where I might start (besides the back of the fuse box -- plan to pull it out and check the output side for that fuse to make certain it's connection is still good). Also, any suggestions for where I might locate the short that was causing the fuses
to blow in the first place? (if its a common issue...)

One other question: Is the security module the same thing as the GEM?

Thanks for any help you can provide!
Mike

 

I had a short while yesterday to start scoping out the problem, but still haven't located the cause. It appears the output side of the fuse holder for slot # 19 -- 4wd/Doorlock +etc module (input being the +12v is good) may have been knocked loose inside the fuse box. I can't see it in the slot for that fuse, and have determined that I have no power going to the 4wd control module / GEM (Circuit Board is labeled GEM).

So, my next question is this: For my 2003 F250 diesel, which colored wire coming out of the back of the fuse box correlates with the fuse #19? I'd like to remove it from the plug connector, add a fused Jumper directly inline with that wire so that I can continue tracking down my 4wd issue.

Second question, is there a free source online for the electrical wiring diagrams? I've used the site linked on this website for diagnostics help, but it links to a Motorcraft service page when I click their link for wiring diagrams.

Your help is appreciated and urgently requested as I have gotten stuck on mostly flat ground twice now in the woods (decomposed granite soils) where I work as a forester, and snow is in the forecast for the next day or two.

Thanks!
Mike

 

Welcome to FTE, Mike.

I'm sure someone will come along here shortly that can be of more help.

But I'll give you bump.

 

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