I drive a 2001 f-150 lariat and every time when it rains my electronics decide to have a seizure. The symptoms include the following:
1. Radio will stay on when the key is completely out of the slot
2. headlights will turn on / flicker even with the switch off
3. 4wd will try to turn engage going 70 down the highway (not recommended)
4. The starter will try to engage with the key out of the slot
5. interior lights will stay on no matter what
6. the ac/heat will blow even with the motor off
7. the dinging sound like the door is open will play constantly

If anyone has any tips or solutions please help

 

Your windshield leaks
It leaks water on your GEM which then goes nuts....

Get the windshield resealed
Dry your GEM and clean any corrosion

 

Agreed with above.

It’s unfortunate that you can’t harness that mess into a legit remote start function.

 

Water is also getting into the fusebox which is underneath the GEM module.

Dry it out, keep it dry, and cross your fingers that there is no permanent damage.

 

I had exactly the same problem/symptoms on my 2003 Lariat and decided to bite the bullet and replace the GEM module. Although many guys say the water is getting in from the windshield, I don't think that is always the case. One recommendation I got was that there may be a fine crack in the body seam below the windshield (photo attached). There is also what appears to be a sound dampening "sponge" in that area that holds the rainwater from draining, allowing the water to drip slowly into the crack in the body seam. After I replaced the GEM, I lathered that seam with silicone caulking and after several heavy rains, have not had the problem again.
This link is a good short how-to video to remove the GEM.

You Tube

This link is also a thorough explanation for removing the GEM, but goes on and on about how to repair the GEM.

You Tube

I bought a used GEM on ebay, but decided I didn't want to risk it, so I spent more for a rebuilt one from Rock Auto.
Hope this helps,
__________________________________________________ __________________
2003 Ford F150 “Lariat” supercab stepside 1/2 ton P/U 2WD 5.4L EFI 2-valve; 8-cyl

 

Interesting. What do you think caused that crack?

I know mine was windshield, top dead center, since it would drip down from above the mirror and leak from the pillar handle if it rained hard enough.

 

Yep, that's where mine leaked. In the area anyway..it was the cab body overlap. The overlap is half welded and half silicone. In my case, the silicone sealer eventually dried out and fell away. It leaked pretty good between the welds. Tested that by forming a barrier around the area with plumbers putty and filling with water. That was the leak alright.

 

just test it. get a water hose and move around until you find the leak. mine was the windshield as well, passenger side upper right corner. pretty easy to verify.