Hi Guys,

I started a thread yesterday (O/D Flashing and Fuse Blowing Help Needed), but as I have worked through my issue, I think I have isolated the problem and I think a new thread would be better to keep everyone from having to read so much backstory.

Whenever my center dome light is activated, I blow Fuse #8. This happens whenever a door is opened or if I twist the headlight switch. Blowing this fuse seems to cause tons of problems - odometer and speedo don't work and tranny goes into limp mode.

It blows the fuse whether or not there is a lightbulb in the dome light. I have a Power Probe III and ECT 2000 and fluke multimeter at my disposal but don't really know how to use them all that well. Hoping someone might give me a clue on how to start to troubleshoot this circuit in a logical way...

Thanks!

 

That circuit also lights the bed illumination lights on the cab roof, and the courtesy lights in the doors. Remove them all and replace the fuse. If it blows again, there's a wiring problem. If it doesn't, start reinstalling light bulbs until the fuse blows; then you've identified the culprit.

Is this a crew cab truck?

 

It is a crew cab truck - 97 F-350 Crew 7.3 250K on odometer.

Will try what you mentioned - thanks.

 

Just did the lighbulb test recomended in second post - all lightbulbs out and fuse didn't blow...good news. Put lightbulbs back in and fuse still didn't blow. Hmmmm...

Closed all doors one by one and when I closed the passenger rear door, fuse blew. Well - finally found some wiring between door and frame where the insulation had cracked and was probably shorting out on the door frame.

Wow - wasted a lot of time on this - mental note to self - always start with a solid inspection and know pattern of wiring before looking deeper.

Thanks everyone!

 

The rear doors on the crew cabs are kinda known for this. I wouldn't say it was wasted time; you took a methodical approach and narrowed down the problem without spending a lot of money on parts, and without paying someone up the wazoo.

 

Thanks again for the help, Madpogue - you are right, hardly anything spent on parts or repair and hopefully next time I will be a better troubleshooter from the get-go.

Electrical issues are tough ones - glad they don't happen too often...