Hi, it's my first post. I should have signed up sooner. I have a 1997 Ford Expedition 5.4, Eddie Bauer. I have owned it for about for three years and put around 30,000 miles on it.

It's starting to go downhill. I wish I had taken better care. It's not like I have been particularly hard driving. I don't off-road, I try to drive in a way that saves gas, not too fast. I just haven't stayed on top of things like I should have.

For the first two and a half years the truck was great. Not any problems at all. Over the last couple of months though, several things have started to happen, like the alternator died and I shot out a spark plug.

But today was really weird. I haven't had a chance to look into it, since it happened right before it got dark outside. I started the truck to drive to the store and after the normal sounds and dash lights went off I heard another beep. I thought it was strange. I started driving and it felt like it wasn't shifting the automatic transmission into second like normal. It wasn't. It's not too bad, it just revs to about 3000 rpms and I think normally it revs to about 2300. After getting on the highway it seemed as far as I could tell to shift through the other gears like normal.

However, in addition to this, and I'm trying to keep this short so people don't lose interest, but I'll be glad to elaborate if you need more information, several other things happened. Here is all the information I have.

Today :
It stopped raining, but it has been raining continuously for weeks.

The driver side window is up and won't roll down.

The speedometer doesn't work. At all.

Several times while driving, the dashboard beeped and some dash lights flashed. It was quick, but they seemed to be 4x4, AWD and a couple others.

I think a couple days ago the airbag light came on. It may have been on before. Just throwing that out there.

The heater/vent stays on even after I turn the truck off and take the key out.

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This is all very weird. I'm sure it's all related and I think it has something to do with the rain. I'm really not very knowledgeable about fixing cars but I just think water got into something and caused problems. Any ideas good people?

It's a hard topic to google! How do you put that into the search bar? I have to drive south in the next week, only about 500 miles away, but I really need my truck to get me there on a stress free trip! I also don't want to damage anything.

From what I could google, a couple items stood out. I have something on top of my rear axle. In the middle, called a VSS? It monitors speed to help the transmission shift. I also have something called a GEM. I think it's a control box for my electronics, but I can't find any more information on it.
It could be a fuse issue.

I'm really hoping this isn't something big that costs a lot of money and time to fix, but there you know, who really doesn't when their car has issues?
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TL;DR

Or to dum it up:

After weeks of heavy rain on an older truck with leaks, my speedometer goes out, my driver window only won't go down, the transmission revs too high to shift to second, the heater stays on even after the key is out, the dashboard beeps from time to time and some 4x4 lights flash.

 

Leaky Windshield Syndrome.

Water leaks down into the GEM module and the fusebox and causes all kinds of havoc by shorting multiple circuits together or enabling or disabling functions.

Get the windshield re-sealed (or replaced) and dry out the fusebox and GEM module. If you're lucky, there will be no permanent damage. Otherwise, replacing the GEM module and/or fusebox may be necessary.

 

After you get the windshield resealed it could take days or weeks for the GEM to dry out, depending on how warm and dry it is there.

 

Electric space heater and a box fan will speed things up.

 

If I want to dry out the GEM can I remove it? ,where is it?

Can I drive like this in the meantime? Can it cause the car to stop running completely?

 

If you can remove it that would be best, connectors and the like can hold moisture for a long time otherwise. Water doesn't really hurt electronics, but operation or applying voltage is what kills them.

 

So I'm looking online and some people say the GEM is beind the glovebox, is that true? So by driving around I could fry the module? Should I spray something on the connectors?

It's oregon, it's not drying out for a long time.

 

The GEM module is on the back (top) side of the under-dash fuse box.

 

Oh ok, so it's right above the foot operated parking brake. I don't know what I read that said it was in the glove box.

A couple weeks ago my windshield wipers stopping working for a couple days, again after heavy rains, I'll bet this was why. The GEM got wet.

 

If you can, clean out any connectors or pc boards with a non residue type solvent.

 

Can't really get to the pc board that easy in order to use solvent.

 

Yes you can remove it but it'll take several hours to do so. You have to disconnect the battery, and then remove the under dash fuse box to get to the GEM on the back side of it.

I would first run a hair dryer up there for a bit to speed up the drying process.

 

The GEM doesn't affect the engine since the engine has it's own computer. As long as nothing safety related isn't disabled you can drive the vehicle.

 

Thanks. I'll pull it up today and put a hair dryer to it. It has been RAINING!

So there is a good chance once it dries out the electrical things like the speedometer will start working again?

What kind of spray would you put to it? WD40 or a dielectric silicone compound?

Thanks so much for all the help!

 

Neither. Look for an electrical contact cleaner.

You have to stoop in the inflow of water first, otherwise you'll waste your time' Speaking of time, you don't have much because you have to get it dried out before corrosion starts. Once the electrical stuff corrodes, it will need to be replaced.