The Diesel Stop banner

Blowing fuse # 17

30K views 19 replies 10 participants last post by  drawmer 
#1 ·
I lost running lights, tail lights and instrument Illumination. I lost fog lights too. Fuse # 17 blows as soon as I turn the lights on. Any suggestions?
 
#2 ·
Sounds like short to ground in the running light circuit. /ubbthreads/images/graemlins/shrug.gif I'd look at the lights, are there any that have physical damage. I'd start there. Make sure there hasn't been damage from under the truck maybe at the rear shorting something to ground.
 
#3 ·
That's what I'm in the process of doing now. None of my lights have any damage to them and I agree something is going to ground.
 
#5 ·
Do you have a trailer brake controller installed?
If so unplug it replace fuse and give it a try, maybe the TBC is fritzed out.
Is # 17 the only fuse blown.?


[ QUOTE ]
Upgraded Headlight Wiring Harness, Diode Mod for Dims

[/ QUOTE ]

I dont have any experiance with the above could any of it be related?....R
 
#6 ·
Sorry, I've been gone. Yes 17 is the only one blowing. The Brake controller still has power to it so it's OK. I'm thinking the trailer wiring is on a completly different circuit. I'll hook up to one of my trailers in a moment to see if that works....Any other ideas?
 
#7 ·
Yep, trailer is seperated. Kind of a long shot, but does the fuse blow as soon as you put it in? The is the possiability that one of you S/T/T lights on the truck has a damaged filiment causing current to flow to the running lights circuit. I know this has caused all kinds of problems in the past.

Keep us updated /ubbthreads/images/graemlins/smokin.gif
 
#8 ·
Nope, Tried one of my trailers a while ago and no running lights. The brake and signal lights work on the trailer as on the truck, but that's it.

The fuse doesn't blow till I turn the lights or parking lights on.
 
#9 ·
ttt
 
#10 ·
To isolate a problem like that you need to take things apart. Have you done ANYTHING to the truck recently? Pertaining to the lights? If so start in that area of course. Try unplugging the trailer tow harness under the rear, the tail light plug under the rear, and you dont need to blow a fuse every time either, take an ohm meter, read from the brown wire on the tail light circuit to ground, it will most likely show a short, or VERY low impedence. Then if none of the isolation unplugging works, wiggle wires in the harness, see if the short goes away. Do it kind of slowly, so when it does go away you know what you were wiggleing!
Let us know what you find,
 
#11 ·
Mine started blowing one night when i hooked to a load of new equipment trailers to haul. Come to find out that it had to be the bottom trailer that they loaded was wired wrong or something. got back and hooked to my trailer and it has not done that since. Went through about 15 fuses from alabama to houston
 
#13 ·
if you don't find any bad lights or loose or damaged connections,start looking at wiring harness under truck for some damaged rubbed off wire insulation.bare wire might be shorting on frame or some other metal.happened to me not to long ago! /ubbthreads/images/graemlins/depressed.gifif its a little spot its pretty hard to track down.start at one end and work your way back.i did this three times before i found a tiny little hole in the insulation.
 
#14 ·
The only thing that I did was hook a new radio into my illumination circuit. I've cut that wire for now with no help. I even unplugged the new radio completely and the fuse still blows. I know, I don't put much in coincidence like I must have done something. But I’ve back tracked everything that I did with zero results.

I’m jumping through hoops today trying to finish up a few other projects and haven’t even had time to look at the truck. I have to leave for work this afternoon and will start back troubleshooting the problem when I get back home about a week from now.

Thanks for all the replies so far.
 
#16 · (Edited)
Hi Everyone, I have a very similar problem with fuse 17 blowing as soon as marker lights are turned on. My situation is that all 4 corners of the truck have a short with marker positive and ground, all 4 turn signals shorted with ground, and Positives of marker lights and all turn signals are shorted with each other as well. Its almost as if both marker and turn lights are touching ground somewhere. Ive took the truck apart and unplugged everything. Mirros, all lights on outside, instrument cluster, trailer brake controller and even the turn signal switch. Anything that could possible be shorting I unplugged. I also looked at all the wiring under the hood, under the body and at the rear under the bed. No signs of damage or shorting. I also plugged in a continuity buzzer on the bulb socket of marker light up front and tugged on every wire anywhere I could and no break in buzzing. I am just completely baffled as to how this kind of short is even possible. Strangely enough the turn signal fuse isn't blowing but I can hear the relay shorting out when they turn on. Am I missing something?
 
#17 ·
I had a similar problem recently where my running lights in the front stopped working. I had to take it to an electrical shop to have it diagnosed. They found that the wiring harness that runs on the drivers side down by the shock had rubbed through the loom cover and had shorted out 2 wires. Sounds a lot like the problem you are having. Mine only blew the fuse once, then it was fine (except my running lights still didn't work). Check that harness real good, I've heard of guys replacing shocks and pinching wires in that bundle before. Mine was just worn from vibration, that and the factory loom cover was not installed right. Hope this helps.
 
#19 ·
Checked that area, my truck is an 03 7.3 so my wires on the driver side run up under intake and battery. It doesn’t go near the shock. I’ve now dug into front doors and no shorting going to the mirrors. At this point is there even a way for me to narrow it down? I know there is a few trailer wiring relays by the brake booster area, but it would have to be 2 relays failing at the same time which is not likely on top of the relay shorting out. I looked on the diagrams and those are the only non wire related failure points. Everything is disconnected so it’s a wire short but where. I literally looked and rugged on every wire that contains marker and turn signals.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top