Hey guys, I posted a thead 6 months back regarding the infamous electrical gremlins caused by the windshield leaking into the fuse box/GEM module. Here it is if you want the background.

https://www.ford-trucks.com/forums/1...-persists.html

Unfortunetely, problems have returned. When I shift from park to drive or reverse, the radio turns off and the basically all the accessories won't function for 25-30 seconds. Then everything works fine until I shift gears again. Oddly enough, I discovered that when I pull the 5 amp fuse (location 20), everything works perfectly. The description of the circuit via the owners manual lists: Audio, Four Wheel Air Suspension (4WAS) Module, Memory Module, GEM Module, Digital Transmission Range Selector.

1. I had the windshield replaced in January and I took the Navi through the car wash with the dash apart to verify no water is getting in at all.

2. I just replaced the fuse box with a brand new one from the dealer on Friday. ($315)

3. I have 3 used GEM modules in my possesion, 2 have re-soldered contacts. I tried all 3 and each one left the Navi with the exact same symptoms. So I am ruling out the GEM for now.

4. I have inspected all related wires and harnesses that can be reached with reasonable effort and did not find any evidence of pinched wires, corrosion, or shorts.

5. I bought a new Digital Transmission Range Selector today, but have not installed it yet.

If the DTRS does not fix the problem, what possible consequences will I face if I just drive with that fuse pulled? I have yet to find one single function that its preventing from working, but obviously Ford put the circuit there for a reason. Thanks for any help.

 

I just installed the Digital Transmission Range Selector today. It made no difference, fuse pulled and everything works perfect, fuse in and the accessories cut off for 25 seconds when shifting gears.

Anyone know what this circuit actually does?

 

It does several things: Audio, Four Wheel Air Suspension (4WAS) Module, Memory Module, GEM Module, Digital Transmission Range Selector.

 

Yes, but all those components still work even when the fuse is pulled.

 

Are we talking about the #20 fuse under the dash or under the hood?

 

Under the dash.

 

Pull fuse #24 from under the hood and see if the accessory blanking problem is still there. The tranny probably won't shift at all since this is the shift solenoid circuit. But what I'm trying to see is if one of the shift solenoids is problematic and drawing down the power.

Also, did you happen to notice if pressing or releasing the brake pedal affects the problem at all?

 

I thought so, just wanted to make sure. The #21 fuse under the dash provides power to the #20 fuse. So you might want to make sure fuse #21 is okay as well.

 

Fuse 21 was fine, pressing and unpressing the brake made no difference. The accessories still blanked after pulling #24 under the hood and shifting the gears.