I have several electrical problems that all started at the same time. When I start the truck it dings a few times under the glovebox also the speedometer stopped working and the heater fan stays on when the key is off unless I turn the control switch to off. I had this problem about a month ago for about a week, then it kinda fixed itself haha. any help would be appreciated this truck is a 1998 F-150 Supercab 4X4 with a 4.6L and an Automatic

 

sounds like you have symptoms of a leaky windshield and water getting into the GEM.

try a search with the keywords "GEM" and "leaky windshield"

check out this thread, specifically post #4
https://www.f150online.com/forums/el...r-windows.html

 

Here I thought I had a problem all to myself, lol. Mine is doing the same thing but the airbag light stays on also. I just did a ton of searching and found instructions for removal of the GEM but nothing saying how to repair it. Can you just take it off the fuse block and clean the contacts and put it back together without programming anything? Some of the posts I've read contradict each other so I'm a little confused on the issue.

BTW, here are the instructions I found for removal. They were linked in another post on this site, http://www.mediafire.com/?m9dcm0mgnvb