So, I go out to get something out of the truck today & I notice there are no dome lights. I go back out later to investigate & find I have no glove box lights or under hood lights either.
The 4x4 switch does nothing, no lights, no relay clicking in, nothing.
The red THEFT light in the dash doesn't come on when locking the doors.
The wipers no longer work (they did just the day before when I added wiper fluid).

The door locks still work, headlights, fogs & stereo are ok.

I've checked every fuse in the cab (especially #27.. I believe it controls most of the things that are not currently working) & under the hood that I can find & all are good.

Am I missing something here??

I've had similar issues in the past (wipers & turn signals quit, but after replacing the multi function switch, everything was ok).
The dome lights have been out before, but usually spraying wd-40 in the door switches fixes this.

Thanks for any info

 

24 hours & Nobody has any ideas? Really?

I've seen there have been quite a few "bans" & "i'm leavings" lately, but I was sure somebody would chime in here....

 

Maybe a bad GEM module. It controls all of those things I think.

 

i think the gem module fuse is blown

 

Check condition and security of ground G101 - driver side near the battery, bolted to the radiator support.
Also check G103 - underhood, driver side, halfway back, bolted to the inner fender apron.

 

Thanks Bob,
All the grounds are tight & no corrosion, but I'm going to remove all the bolts/ring terminals & sand off the connection areas again as soon as I get a chance. I even checked for corrosion in the battery terminals.

Note: I replaced all the OEM grounds and connectors with 1/0ga wire when I upgraded to a 200a alternator.

Later the same night everything went haywire, I went back out to check & everything worked perfectly. Today, the same problem as before.

Luckily, it wasn't raining, I didn't really need the interior lights or have the need for 4x4 when I had to go out of town today.
Theft light probably wouldn't keep anybody from breaking in & stealing my pack of gum out of my cup holder though.

Ford said it "might" be a bad module (I'm guessing the GEM as mentioned before) but they'd have to diagnose it at the wonderful cost of $75 per hour.

 

Wiggle test.

Put someone in the cab watching, while you wiggle wires.