1999 electrical issues

[Justinwolf]

Hi, I have a 1999 Expedition, I’ve been having issues I believed to be related to the GEM and water leaking in. Dashboard warning lights flashing, cabin lights coming on and the car starting by itself, even when already running, and most recently the stereo and 4wd not coming on.
I just replaced the GEM today, and haven’t driven it long enough to confirm what it if anything it did fix but immediately I noticed that the stereo and 4wd aren’t working.
They come on for a minute and then go out. Was hoping the 4wd was just a light not coming on but the 4wd itself doesn’t seem to be working.
My next thought was to replace the fuse box itself? I tend to think there could be water in it causing shorts or corrosion..
Any thoughts before I head that route? It was a giant headache getting it out and back in, can’t say I’m looking forward to doing it again…
Thanks for any input

 

[Kevmobile]

car starting by itself is definitely GEM-related. Can you verify your build date (pre or post facelift)

Have you verified there are no vacuum leaks at the actuator? You can use a disposible vape with a tube as a smoke machine to see.

Also, have you verified 12V at the transfer case motor?

Check your transfer case relays (see forum).

I don't believe the stereo is controlled by the GEM. This could be an issue with the fuse box. Again, check for 12V at the stereo connection and report back.

If someone could please chime in with a wiring diagram

 

[Justinwolf]

So, had a chance to drive it and a good number of the issues are resolved..
The stereo however continues to blink on and off..
And the biggest problem is the the 4wd which previously would not come on is all of a sudden not going off..
I’m hoping all of this can be related to the fuse box itself being corroded or wet? My knowledge of car wiring is minimal and that’s already pushing
my abilities.
I’ll probably order a new fuse box and give it a go but in the meantime does anyone have any ideas on how to get the 4wd to disengage?

 

[Kevmobile]

So, had a chance to drive it and a good number of the issues are resolved..
The stereo however continues to blink on and off..
And the biggest problem is the the 4wd which previously would not come on is all of a sudden not going off..
I’m hoping all of this can be related to the fuse box itself being corroded or wet? My knowledge of car wiring is minimal and that’s already pushing
my abilities.
I’ll probably order a new fuse box and give it a go but in the meantime does anyone have any ideas on how to get the 4wd to disengage?

You would be best off replacing the GEM. Also, you can do the brown wire mod to get rid of the 4x4 cutting in/out on its own