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Discussion Starter · #1 ·
97 F350 - stock - no extras at all.
Short background for my problem - Very dark night - I hit a huge hole in the road with the left front tire - like hitting a brick wall! It jolted the entire truck.
#4 DASH fuse instantly blew (it controls the running lights / instrument panel / warning chime - buzzer / and turns on the relay for the fuse for the trailer lights under the hood)
However - I tried to replace it - and it instantly blew again.
I looked for the "problem" (bulbs / wire / etc.) but found nothing obviously wrong.
Replaced the fuse again - it took - and worked for several weeks.
Then - out of nowhere - it blew one morning. It instantly blew 6 or 7 fuses as I searched for the problem on the side of the road on the way to the jobsite (truck full of workers). Out of nowhere - the 8th fuse took and lasted several weeks.
This same scenario repeated a couple of times - and again yesterday.
However - yesterday it would not stop blowing fuses - so we made it to the jobsite with emergency flashers - until daylight.
After the truck sat for a few hours - I tried to replace the fuse - and it instantly blew.
When ready to leave for home - I tried again - and it took. It worked all the way home and all evening while I searched for the problem (cheked and rechecked bulbs / shaking wires EVERYWHERE - spraying water on external wires / etc.)
I just replaced the dash headlight / park and dome light "Push / Pull" controller - hoping this might be the problem. (One connector on the harness plug had a very very slight brown burn stain - but not bad at all. The unit itself looked OK - but now it is replaced.
I hope its not something on the back of the instrument panel.
My mechanic said it might also be the controller assembly on the steering column (wipers / blinkers / high beam) unit. I'll try it next - but I thought that unit only controlled the headlights - I didn;t think it had anything to do with the "running / park" lights???
The problem is that when I have time to "test" for the "problem" - the fuse won't blow!
Any ideas if the Push / Pull controller is NOT the problem?
 

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You have a long road ahead of yourself trying to figure this one out. Somewhere there is a wire going to ground that is shorting out the circuit and that can be a bear to find.

I would start by looking for any loose wires or ones near a ground such as the frame, bumper, or body panel.
 

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Starting right the truck at the firewall, trace the wires back.
Pay close attention to the trailer wiring.
If no that, I would look into the cab light wiring.

Sent from my SAMSUNG-SM-G890A using Tapatalk
 

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Use this site to locate everything on that fuse:
Search Wiring Diagrams

On the same site, you can check for TSBs similar to this one:
 

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Discussion Starter · #5 ·
I changed out the main (push / pull) park / headlight / dome light unit - and so far the 15 amp fuse in the # 4 position of the dash fuse panel is holding. I think that the coil / resistance spring on the dome light resistance dial was shorting out.

So far so good - 250 miles - no blown # 4 fuse!
 

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Discussion Starter · #7 · (Edited)
I'm not sure - according to the text on the inside of the fuse panel cover - it controls the running lights / instrument panel and dash lights / warning chime - buzzer / and turns on the relay for the fuse for the trailer lights under the hood
 

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I changed out the main (push / pull) park / headlight / dome light unit - and so far the 15 amp fuse in the # 4 position of the dash fuse panel is holding. I think that the coil / resistance spring on the dome light resistance dial was shorting out.

So far so good - 250 miles - no blown # 4 fuse!
I had the same experience. Replaced all the cluster back light bulbs at the same time and it looks great now.
 
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