This is quite baffling. Last week Thursday we parked the truck (97 expy eddie 5.4) at the local TSC for 3 hours in the rain. Upon start up the rear wiper and drivers window wouldn’t work (others did) and the 4x4 indicator and OD off lights were flashing on and off while in 2wd. When I put it in a4wd it would cycle between a4wd and 4hi We drove home and the following day nothing worked, absolutely dead. The battery and alternator are both less than a year old. It won't jump start either. I Can’t get codes because it won’t do anything. Anyone have any suggestions?

 

GEM module....Windshield leak...... Big PITA! Sorry.... wish I had some good news for you.

 

Goody! Where is it?

 

It is under the dash on the left side of the truck. You will need to remove the lower panel under the steering column. Then remove the fuse panel. It is located in the fuse panel. The entire fuse panel needs to be replaced. Before I did this I would check all the fuses to make sure none of them are blown. This is a common problem on the Expys. If you do a search for GEM module you can read into more detail.

 

Have the windshield resealed first, and verify it's watertightness before replacing the GEM.

 

Thanks everyone. We are on it. I'll keep you posted

 

A new fusebox and GEM later and we are good as new. I am waiting on a reseal of the windshield to make certain we don't have this problem again.
Thanks all

 

Glad we could help

 

Long post ... but very thorough.

My 99EB expy had the radio die while driving down the road. I shifted to neutral, shut the engine, restarted and the radio came back on. When I shifted back into drive, it died again. I did this two more times then arrived home.

In the garage, turning off the key, the heater and instrument panel stayed on with the key in my hand. Rocked the key a few times and all went off.

Fast fwd to 9pm.
Went down to the garage to empty the trash and heard the truck blower running. Walked over and it stopped. Waited a minute or two and it started again then stopped. Looked in the window at the dash and when it started again the blower ran and the instrument panel lit up like the key was in run. Also the antilock brake system was testing itself.

Spent till 01:30 am looking for the problem, wiggling plugs, removing fuses, shaking wiring harnesses even unplugged the remote starter ... could not find the trouble. Disconnected the battery, put on chargeer and went to bed.

Next am, connected the battery ... still the same problem. Took my 1/2" wrench with me to work, parked the truck, still same problem, undid the battery went inside. Checked here for information ... found all I needed to know about leaky winshields, fuse panels and GEM modules.

Went home that evening, still same problem. At 9PM, with the battery still disconnected, I removed the driver's kick panel, knee panel etc to expose the fuse box. Using a 10mm socked I removed the two very large plugs that connect to the fuse panel.

A dozen or more screws later I had the fuse panel and GEM in my hand.

Looking up at the black plastic mounting block that the fuse panel just cam out of I could see where the water had ran down the top curve of the bezel and landed on the back side of the fuse panel and GEM.

I'm an electrical engineer with a few automotive designs under my belt, so I had no problem playing with the GEM and here is what I found. The GEM plugs into the back of the fuse block. Removing the screws allows you to wiggle free and unplug the GEM - box and all.

The GEM box is black plastic with just three plastic clips holding it closed. The cover of the box is molded with round overlaping edges and has no holes. Thus water dripping on the box can not get into the electronics.

Opening up the box shows the circuit board mounted on stand offs, solder side up with a 1/2" border all the way around and the plug sticking through the back about an inch up.

Even if water got into the box, I don't think it could reach the circuits. Because of the back tilted mounting angle of the fuse panel, water would run out the side vents and the cover itself long before reaching the circuit board. There was no sign of water marking on the inside of my GEM. In MY OPINION there should NEVER be a reason to replace the GEM for a water problem.

I reasembled the GEM and turned my attention to the fuse panel.

Observation of the bottom of the panel (where the large plugs connect) shows water staining along the entire bottom where the plug sockets and the forward tilt mounting of the box formes a cup for water to collect in. Water marking had made it past the first row of pins to just short of the second row. I could see where arcing had traveled from one pin through the water to another pin. ( explains that electrical smell I had ... probably making hydrogen )

The fuse panel box is riveted shut by the bolt sockets of the large plugs so it cannot be opened. It can be slightly pried open along the bottom edge enough to shine a light in and look around. I observed that the panel is just a BUSS protector for the many BUSSES that run from the pins to the fuses to the relays etc.

The BUSS network is made from thick heavy metal that, in my opinion, would not corrode enough to degrade the performance of the electrical system for quite some time.

While I had the bottom slightly pried open, I very carefully hand drilled a few tiny holes in the bottom seam of the plastic box that would allow any trapped water to escape.

By 3:00am I had the whole thing dry, digital pictures taken, truck reassembled, and drove into town for gas. All went well and still is.

While reassembling, I noticed the pocket in the frame under the door moulding where

The next day I took the truck to Portland Glass ( a glass doctor company ) and told them my story.

They rough quoted me $65 for a "edge reseal", $100 for a "remove and reseal", and $275 for a "replace the windshield we broke while trying to remove it and reseal it". I wished them luck and got a lift to work.

Later that afternoon I picked up the truck. They said the winshield was factory original and that 50% of it was never sealed ... a factory defect. They said you could put one hand inside and the other outside the winshield and rock the glass in and out with ease. the water intrusion was very old and very obvious around the driver and passinger sides.

They said this was a significant hazard in accident, as the winshield could fly off and become a projectile while leaving me unprotected.

They charged me $75 for a "remove and reseal" as it came out very easily.

Well thats MY story ... don't call me if anything you do with this information does not work out for you. I'll load up the digital pix as soon as I can.

 

Could this also be the reason my passenger side "in the mirror" blinker stays on with the key out of the ignition? This is on an '02 Expy.

 

cracked windshield, leaky seal, affecting computer module, mine did same thing till they replaced windshiled and computer. luckily it was under warranty.

 

OK, I'm no electrical engineer or anything but your post definitely got my attention. I am quite certain that I have a short that is somehow connected to my radio and to my electric windows. I have an 03 Expedition XLT. From time to time, the radio will work just fine & other times it will shut off. When it does this, sometimes I hear a semi-welding sound somewhere in teh passenger side of the panel but ALWAYS leaving teh window inoperable also. If I hit a bump just right, it may come back on, sometimes if I tap my dashboard (lovingly) it works, too. My question is, why in the world are these two things related. How can I get to it without destroying everything in my truck. Any ideas? All help and advise is GREATLY appreciated!

 

I believe the only common point you're going to find is at your ignition switch or a ground wire.

 

Pull the plastic kick panels and inspect your ground connections.

Steve

 

Thanks a ton! I appreciate all your help!