In the last 48 hours I've had to reprogram both of my key fobs twice. It's a 2001 F250 CC Lariat with 64k. Battery never lost power that I'm aware of. Each time I've turned the ignition to run and then stop 8 times, leaving it on run the final time. I the press a butting on each fob and it resets to the computer and things work fine. Not sure why it's getting unprogrammed. Any ideas?

 

Whatever stores the key fob info is losing it's mind. I wonder if the GEM has a CMOS battery in it that's dead? Or if it's flash, it's bad.

 

GEM? Sorry for my ignorance.

 

In the earlier F-series, it's the module that controls the doors, locks, and a few other things. Generic Electronics Module or something to that effect.

It's losing it's memory. There used to be an issue with the windshield leaking and the GEM getting wet - is the passenger-side carpet wet?

 

The GEM is on the driver's side, above the fuse box.

 

You are correct, it is on the driver's side.

 

The carpet was not wet on either side of the truck. I have noticed that it seems to happen only when the truck is hot. Not from running but from being parked in the sun. A few times now it's been fine in the morning, key fobs working like normal, but when I get out to my truck in the parking lot the key fobs won't work and I need to manually unlock the doors. When I get in it fires right up like nothing is wrong. Get home and try the key fob, it works fine. It's really strange.

 

"Hot" and electronics and intermittent function usually means that there's a bad connection on the circuit board (bad solder joint, for example) and when the board expands, the connection opens. Let it cool back off, and it starts working again.

It will, however, eventually completely fail.

First though, I'd see if the GEM connection is a good solid connection.