1990 F250 XLT Lariat 4x4 7.3 IDI. So here's where I am at. Sunday I went out to my truck and had no dome light or stereo. Both of these worked on Saturday. Last time I had a little problem like this show up was in my E150 van about 10 minutes before everything went out and I realized the alternator was shot. So I broke out the multimeter and checked some things out to see if it was happening again. Both batteries showed 12.25ish with the engine off. They were around 14.14 with the engine running. So I didn't think it was the alternator. I then proceeded to check the dash fuses. I pulled the fuses for the stereo, dash, instrument panel, etc. All showed good. I did notice that when I turn the key to the "on" position (not to the point where the wait to start illuminates, just the "on" where the fan or stereo comes on) there is an audible click about 1.5 seconds afterward. The "Rear Antilock" light blinks for a split second and goes away right when you hear the click behind the dash. Also, the "Engine" light is illuminated when the key is turned on, but goes away if I actually start the truck. Sorta scratching my head as to what to check next. I did disconnect both batteries and let it set for a beer. Same situation when I reconnected.

Anyone chase down something weird like this already? I ordered a whole new set of fuses. Figured might as well spend $12 on amazon and replace the who knows how old fuses I come across since I will likely be pulling a lot of them to test.

Any help is appreciated.

 

I think my next step will be to check all my grounds. I was fussing around near the wiper motor a couple of days before this started. I may have bumped the ground that is located near there. Just a wild guess. I didn't drive that truck to work today, so I am just reading through all sorts of forums about all sorts of electrical gremlins. Trying to check the simplest things first.

 

Fuse #8 feeds the domelights and the radio memory. There are two fuses for the radio. 11 and 8.

 

Both of those were good when I pulled them. At least according to the connectivity function on my multimeter. I checked most of the fuses when I was under there.

 

Put the meter in dc mode and see what voltage you have on both sides of fuse 8. Should be hot with the key off or on.