F350 horn blows and dome light comes on randomly

Try grounding the horn with a test light off of each lead. If energized, the horn should sound if it's good. If it doesn't, and the test light lights at the horn, then the horn itself should be replaced.

For 1999 Ford Truck F350 Super Duty P/U 4WD 7.3L Turbo Diesel 8cyl the Flasher is located: Behind center of instrument panel.

Hope this help to fint it (remember comment and rated this).

find the horn and tap it with something sounds like its stuck

Bad switch on the light or bad door switch.

you have somewhere short which is draining your batteries.

that fuse powers pcm fuel heater and some other things. when the fuse blows the pcm shuts down. causing it to not run. usually its the heater that is bad. it is located at the back driver side by the fuel pump. you can unplug it and see if it starts. if so you will need to replace the heater

It is the fuel heater, All you have to do is unplug it.

there is a short in the horn wiring, you may disconnect the horn relay, that the easiet thing to do. owners manual should have a layout of where the relay is. Steering wheel switches most likely.

I think your horn relay is making contact from behind your horn buttons on your steering wheel. Usually as time creeps up the insulation that is placed on the positive lead for the horn gets worn out from constant horn action. If it is worn down the horn is touching a ground and completing the circuit and thus making the horn sound. I would start with that first before getting more technical. Let me know. Gabe

is it under the grill toot horn and locate