When I take the key out of the ignition and leave my '02 F350D, electrical things just keep right on working. Like the radio,all the stuff that should shut down. If I lock the doors with the lock/unlock button, the driver's door lock unlocks itself after a few seconds. If I've got the headlamps set over to auto turnon at dusk, come dark the lights will turn on.

I'm thinking this is the gem mod. Right? And easy to get to of course, right in the middle of the dash I'm told. Over four hours labor.

I was told this problem was caused by a faulty windshield seal that allowed water to run down through the firewall and over time, ruin the mod. Anybody heard this? So is there a Ford bulletin on it?

 

Common "leaky windshield syndrome", sounds like.

On an F150, the GEM module is above the fuse box, upper left side under dash. Severe cases may require replacement of both the GEM module and the fuse box, in addition to repairing the windshield leak.

On the F-SuperDuty, the comparable functions are controlled by the VSM (no GEM module). It's up under the dash as you described.