200 F350 Crew Cab 7.3, if the truck is parked nose down and it rains heavy or snows I get bad problems. One being the heater fan will run without the key turned on. The other is I will loose my speedometer and the over drive light will flash. Once things dry up (?) everything is fine. This has happened to me twice now, this only happens when the truck is parked with a slight down hill position. Any ideals? I do leave the settings in a defrost, high heat, high fan position so the truck can defrost and be warm when I am ready to leave.

 

Check to see if the windshield has a leak that allows water to collect around the central junction box and other electrical control modules.

Look under and behind the dash in the area above the steering column. If it is wet there, you probably found the problem.

Lou Braun

 

Do uhave a remote start ?

 

x2, my Zu dids this, I just park it nose up hill now

I went through and pumped silicone under the seal around the windshield, no problems ever since.

 

I do have a remote start, it is part of the alarm system, controls windows also.

I will check under the dash around the steering colum and see if I can find any water.

I appreciate the help.

 

Remote start may be a source of problem too. Those usually power the ignition 1 & 2 wires which could be the source of heater coming on at random times. Hopefully u have the schematic on it and can check into that as well.

 

Sounds like water is finding its way into your GEM module. Correct ASAP. Those babies aint cheap. If nothing else wrap a piece plastic around your fuse block. Your GEM is mounted to the back of it. Then fix your windshield leak.