Hi Y'all,

My '99 has decided to go haywire so I'm wondering anybody else has had any of these symptoms? It seems to be worse or more likely to happen after a rain.

As I'm idling the starter will randomly kick on and off.
Starter kicked on once while car was completely off and key removed.
Wipers, radio, dash gauges, work intermittently (they kick on and off on their own but usually all at the same time).
4x4 light will turn on & off (and i hear clicking, not sure if 4x4 is actually engaging or not)
Odometer comes on & off.

I'm hoping there is some wiring harness that these all go to that I can track down if they are shorting together or something but I'm having trouble finding a service manual/full wiring diagrams.

I did find this diagrams link but I'm not clear on how the diagrams all go together:
Search Wiring Diagrams

Thanks for any help!

 

sounds like your GEM module is flaky. The bigger concern is it might be that way because the front windshield is leaking. Have you had some steady rains or hard rains lately?? So you'll have to make sure it is sealed up.

 

Thank you! I have looked up ecm/pcm issues previously when something went goofy but that didn't seen right and the issue was never consistent enough for me to diagnose further.
This definitely seems like a gem issue from what I have been reading about them now.
I'm in MN and we have had both heavy and steady rain intermittently for a couple of weeks, hence my consistent issues now. I don't drive my truck but a couple times a week though so I'm sure there have been times of rain that I didn't use it until it dried out.
I'll pull it out tomorrow and see if there seems to be moisture/staining under the dash or corrosion on the part.

 

I have the same odd assortment of symptoms. I have to turn on the wipers as soon as I start the engine. They won't shut off until I shift into neutral or turn off the engine.

 

I would be thinking all this action has a common relationship with the ignition switch.
The Gem has nothing to do with the start circuit unless there are unusual conditions.
If the Gem were to get corroded, wipers, 4X4 and possible other Gem controlled circuit might be affected.
It all could begin with a leaking windshield or hood cowl that gets to the GEM across the dash ledge then down the steering tube to the ignition switch and ends up on the floor.
If the leak has gone on long enough, maybe the ground connection behind the driver kick panel has also corroded from water wetting so long. This would affect a lot of circuits including the dash display.
They are all under the dash area.
You have to see it if that's the case.
Good luck..

 

Excellent, thanks.

I started at the ignition switch because the starter would not stop running even after the key was removed. Now, at times as soon as the key is turned to the run position, the starter will engage.

At other times, the starter would engage even if the engine was running or whenever it was shifted through neutral.

This pointed to the Neutral Safety Switch. Then the truck wouldn't start in neutral and it engaged the starter every time the transmission passed through neutral. The second NSS solved that with an occasional starter engagement as soon as the key hits the run position.

I ran out of ideas and replaced the starter solenoid. Same weird start issues, only it's intermittent now.

I checked the grounds I could find behind the kick panel. They were badly corroded and showed a solid but rusty ground. I will move the ground to a clean location.

NOW I have to turn on the wipers as soon as I start the truck and the wipers won't shut off unless I'm in neutral or turn off the engine. PLUS there is a short in Fuse 1 (radio) which is blowing fuses as soon as they are plugged in. (Also no map lights, under hood lights, or glove box light)

Thus, I was thinking the GEM. I still think it's a bad ground somewhere, I just can't find it.

Update:

The problems are worse when it is near 20 degrees outside. This morning ALL of the weirdness returned. There was a loud click from under the dash and the pungent odor of ozone and burned plastic. Temperature related fault make me think of something with tight tolerances. I'm pulling the fuse panel and GEM to look for any signs or arcing or corrosion.

 

I was also having starter issues when my truck went wild, same as you where it would kick the starter while already running. Once I walked up to my truck after work and it was turning over in the parking lot trying to start itself with no key in the ignition. I replaced GEM as well as my windshield (that was presumably leaking onto the GEM) and so far all issues (4x4 turning on and off at will, radio cutting in and out, wipers turning on and off, windows not working intermittently, the gear shifter position affecting electronics) have been fixed, though the windshield place told me that they did not see any signs of leaking. It is still winter in MN so I am waiting for a good rain to see if any of these problems come back. But, I would say your GEM is probably bad since replacing mine has fixed all of my issues to this point.

 

That also explains the smell this morning.

So does anyone have a spare fuse panel laying around that will fit a 2002 F-150 XLT 4.2L?

The GEM is a replacement. The inside is pristine, the outside has a coat of poorly applied spray paint. Several of the pins on the panel show corrosion and there are watermarks on the panel.

 

That'll do it! I would be sure to tackle the water leak source as well, otherwise you'll be doing all of this again before you know it. It took me 2 GEM replacements to finally get my windshield replaced, and as previously stated now I'm just waiting for winter to end so that I can see if that did the trick.