Hey guys, I'm completely baffled right now. I have '99 Lincoln Navi 4X4 5.4L intech with big electrical problems. Started a little over a week ago with my heater blower running on its own without a key after it had been parked and off for several hours. That stopped a few days later, but then the stereo would shut down for a few seconds and then power up again after shifting into a different gear. Then wipers started having a mind of their own, then no dome light, 4X4, power windows, and finally now the truck won't shift out of park due to the brake safety switch not recognizing my foot on the pedal.

I continued to drive it until the "not shifting out of park" started and I nearly got stranded at work. After trying to engage all the accessories I could think of and whacking the fuse box with my hand, it still didn't allow me to shift into drive. Then suddenly, several relays in the fuse box went bonkers and only then could I successfully get the shifter into drive and get home. I have kept the truck in the garage now for the past 2 days.

Based off a lot of internet searching, I decided to order a used GEM module from eBay and installed it today. During the install, I was surprised to find absolutely no tell tale corrosion or moisture in either the GEM or the fuse box. The harnesses and underside of the dash showed no signs of rust or moisture. After installing the replacement GEM module, all of the same symptoms that existed right before I pulled the original out remained. These symptoms currently include: not shifting into drive, no 4X4, no power windows, no stereo at all, no wipers at all, and no dome lights.

I would hate to throw in a new fuse box and not have it make any difference. Other than that, I am at a loss. I would appreciate any suggestions, thanks.

 

Have you looked chew marks on portions of you wiring harness where the little critters can get at?

 

Well, you are going to have to do "real" troubleshooting with a meter instead of just searching the internet....

 

Thanks, I will look for that.

 

I'm fine with that, however, you have to forgive me for at least going after the easier/common solutions considering it is currently 12 degrees in my garage.

 

A kerosene heater is your friend at times like this.

 

This thread seems interesting, I plan on doing a closer inspection of the fuse box when the weather warms back up a little.

wierd eletrical problem - Ford Expedition Forum

 

---SOLUTION-----

I finally fixed my Navigator today, it did wind up being the fuse/relay box. I took apart the original fuse/relay box and did find evidence of water and corrosion. I cleaned it up and managed to get it back together and reinstalled. However, several of the same problems continued.

The thread from the link I posted above makes mention of a "hidden" relay that is built into the box and is not serviceable. I decided to pick up a used replacement fuse/relay box on eBay for about $70. It fixed all the problems and now I just need to take the Navi in to get the windshield resealed.

Moral of the story is electrical gremlins on these vehicles are not always a faulty GEM module. It can sometimes just be the fuse/relay box. If you take out the GEM module on one of these trucks and it looks totally dry and corrosion free, replace the fuse box first. Hope this story helps someone, thanks.

 

Thanks for the follow up info. I recently picked up a '97 with similar problems. Got it for a steal so I've been attacking my gremlins with no luck. I was going to buy a new GEM this weekend but I'm going to check fuse box first. Do you know if the functions (volume,CD) of the radio are controlled by the GEM as well? Mines freaking out. I hope your solution fixes mine cause I'm going crazy. Thanks


Bernie

 

I'm not sure about the radio acting weird, mine just powered off completely when it was acting up. just a heads up too, the fuse box is not meant to be serviceable. I was able to get it open with a dremel tool, but it's tough to do without completely destroying it. I did it expecting to have to replace it anyway, but hoping to get some answers . I cleaned it up as it had evidence of water and corrosion on the inside with the hope that I could get it working. However, the part that failed completely is not reachable even after cutting the box open. Again if the GEM looks clean upon inspection, just go ahead and replace the fuse box.

 

I was planning on replacing both at the same time. I only want to take the dash apart once. Thanks again for your help.


Bernie

 

No problem, good luck.