Blowing fuses

[Bigfoot]

I'm not the best with electrical stuff. I have one trailer, when I hook it to my truck, it will eventually shoot a fuse on my truck, before I get home. It just shoots the running lights. Not the tail lights or turn signals. None of my other trailers are shooting the fuse. Obviously, it's something rubbing/shorting out. I've investigated the plug, and all seems normal. How in the world will I ever run the problem down?

 

[M-5]

gonna have to trace each wire till you find the bare spot. I have a sneaky suspicion it where the wire exits the tube chase it is in

 

[jltrent]

Rats may have sharpened their teeth on the wires. It happened to mine until I found it.

 

[talltimber]

First. I would hand trace the wires, looking for problems, if you can get to them.

Second method. Unhook trailer, take out bulbs (or unplug the harness, whichever you have), ground each wire at the hitch end one at a time checking the other end with a ohmmeter to ground. (a helper shaking the wires around to give them a chance to ground helps here)

Third. If all else fails, hook it to a battery charger and watch for smoke. Cut out smoke, splice wire.

Fourth. Totally rewire.

 

[lavacarancher]

Big, the lights are apparently wired a little screwy. The tail lights and running (clearance) lights should be on the same circuit, (brown wire on a flat, 4 wire connector). Turn signals (and brakes) are on separate circuits. Look at all the wiring especially where the wires run over the frame or other metal on the trailer. This is more than likely where the short is. Having found that everything is OK with the wiring check your light sockets and make sure the bulbs are the correct ones for the socket(s), that the pins on the bulbs are not in the wrong place for the socket. I don't know how old your trailer is or what kind of bulbs are used but (for example) some bulb have two elements inside and therefore two contacts on the bottom of the bulb. If you plug this type of bulb into a single contact socket it may short out, depending on how the contacts on the bulb touch the contact on the socket (make sense?).

If you get really ambitious you can rewire the trailer but make sure you insulate the wires as they pass over or around the metal.

One last thing, how many "running" lights do you have on the trailer and how big (amperage) is the fuse? Make sure these numbers line up.

 

[Bigfoot]

15 amp fuse. Probably a half dozen running lights.

 

[JMJ Farms]

First. I would hand trace the wires, looking for problems, if you can get to them.

Second method. Unhook trailer, take out bulbs (or unplug the harness, whichever you have), ground each wire at the hitch end one at a time checking the other end with a ohmmeter to ground. (a helper shaking the wires around to give them a chance to ground helps here)

Third. If all else fails, hook it to a battery charger and watch for smoke. Cut out smoke, splice wire.

Fourth. Totally rewire.

:lol2: And I thought I was the only one who ever tried this :lol2:

 

[tom4018]

Has it always done it? What type connector does it have? Sometimes look around the axles the wires get worn there.

 

[Bigfoot]

It just started it a couple of weeks go. I made a little trip tonight in it. It shot about 20 miles from home. Brake lights and turn signals still worked. I probably should have jumped out, and put one in, but I didn't.

 

[Brute 23]

What kind of truck? Chevrolet or GMC truck?

I had the same thing going on on my 15 Chevy 3/4 ton. It was only blowing the little 15A mini fuse for the running lights.

It was a weird deal because it was doing it with multiple trailers. There was a little stick jammed in the plug under the bumper that I thought was maybe causing it. I hooked back up to the trailer after I pulled the stick and it still blew tge mini fuse. I jerked all the wires off the trailer and re-ran them. It didn't blow after that. Hooked up to the other trailer and it didn't blow the fuse with it either. Almost seemed like there were two issue.

They did not put many spare fuses or a fuse puller with my truck. I went and bought a puller with a big assortment of fuses now.

 

[jedstivers]

I'm not the best with electrical stuff. I have one trailer, when I hook it to my truck, it will eventually shoot a fuse on my truck, before I get home. It just shoots the running lights. Not the tail lights or turn signals. None of my other trailers are shooting the fuse. Obviously, it's something rubbing/shorting out. I've investigated the plug, and all seems normal. How in the world will I ever run the problem down?

I'll text you a viedo tomorrow how to do a continuity test if I don't forget or spend all day wide open.
I can't describe it here. It's simalar to what tall timber is talking about.
You should be loosing tails too though. Something might not be wired right.

 

[talltimber]

First. I would hand trace the wires, looking for problems, if you can get to them.

Second method. Unhook trailer, take out bulbs (or unplug the harness, whichever you have), ground each wire at the hitch end one at a time checking the other end with a ohmmeter to ground. (a helper shaking the wires around to give them a chance to ground helps here)

Third. If all else fails, hook it to a battery charger and watch for smoke. Cut out smoke, splice wire.

Fourth. Totally rewire.

:lol2: And I thought I was the only one who ever tried this :lol2:

I've done it several times on road trailers. It's the last resort but it does work in a grounded situation, and that sounds like what he's got. The thing is, I believe you would have to have an older charger that stays on. I don't think the electronic chargers like I use now would start charging if it senses a ground condition.

When somebody showed me how to do it the first time many years ago I thought we had set it on fire :lol2:

 

[jedstivers]

First. I would hand trace the wires, looking for problems, if you can get to them.

Second method. Unhook trailer, take out bulbs (or unplug the harness, whichever you have), ground each wire at the hitch end one at a time checking the other end with a ohmmeter to ground. (a helper shaking the wires around to give them a chance to ground helps here)

Third. If all else fails, hook it to a battery charger and watch for smoke. Cut out smoke, splice wire.

Fourth. Totally rewire.

:lol2: And I thought I was the only one who ever tried this :lol2:

I've done it several times on road trailers. It's the last resort but it does work in a grounded situation, and that sounds like what he's got. The thing is, I believe you would have to have an older charger that stays on. I don't think the electronic chargers like I use now would start charging if it senses a ground condition.

When somebody showed me how to do it the first time many years ago I thought we had set it on fire :lol2:

Can also use a hot battery instead of a charger.

 

[hillbilly beef man]

First. I would hand trace the wires, looking for problems, if you can get to them.

Second method. Unhook trailer, take out bulbs (or unplug the harness, whichever you have), ground each wire at the hitch end one at a time checking the other end with a ohmmeter to ground. (a helper shaking the wires around to give them a chance to ground helps here)

Third. If all else fails, hook it to a battery charger and watch for smoke. Cut out smoke, splice wire.

Fourth. Totally rewire.

:lol2: And I thought I was the only one who ever tried this :lol2:

All electronics or electral devices run on smoke. If you let the smoke out, it does not work anymore. ;-)

 

[Nesikep]

I use the smoke method as well when I have to, but doesn't work very effectively on intermittent shorts

If it didn't used to blow fuses, the problem probably isn't too many lights on a circuit but a short to ground.. if it's always been problematic changing to LED lights goes a long way in reducing load.

If the lights work for a period of time after you hook up, I'd connect it all, put a new fuse in, work at night, and then start jiggling wires.. sometimes having an assistant can help if they can tell you when lights start to flicker while you're under the trailer.. As many have said, the problem is probably where it goes over a frame rail or other metal and has rubbed through over time.

 

[Bigfoot]

Fooled with it, what time would allow today. Shook the trailer, and wiggled wires. Couldn't get it to blow. Ran a town over, to take the girls to ride, and blew somewhere along the way. I turned the running lights on for the trip, to see what would happen.

 

[Nesikep]

I use the smoke method as well when I have to, but doesn't work very effectively on intermittent shorts

If it didn't used to blow fuses, the problem probably isn't too many lights on a circuit but a short to ground.. if it's always been problematic changing to LED lights goes a long way in reducing load.

If the lights work for a period of time after you hook up, I'd connect it all, put a new fuse in, work at night, and then start jiggling wires.. sometimes having an assistant can help if they can tell you when lights start to flicker while you're under the trailer.. As many have said, the problem is probably where it goes over a frame rail or other metal and has rubbed through over time.

 

[Philip-TX]

What kind of trailer connector are you using? 4-pin, 6-pin, 7-pin ?

My truck has the 7-pin so I has several adapters....

Often time the 12v and the e-brake need to be switched with in the adapter.
You need to check where the 12v is on the trailer side as well as the truck side, and also the e-brakes. Some time the center pin is 12v, also.

I have bought several adapters and had to open them up and switch the blue and black (if I recall) wires.

I keep this in my glove box for times when I come across this problem.

 

[Bigfoot]

Well, you can't smoke it out. I guess I'll have to throw some money at the problem. I'm heading north of me, in a couple of weeks, and they are hard on trailers up that way. Plus, I think it's foolish to pull without lights anyway. Definitely not the truck I went all weekend with another trailer, and never a problem.

 

[tom4018]

Well, you can't smoke it out. I guess I'll have to throw some money at the problem. I'm heading north of me, in a couple of weeks, and they are hard on trailers up that way. Plus, I think it's foolish to pull without lights anyway. Definitely not the truck I went all weekend with another trailer, and never a problem.

Wish you were a little closer so I could help you with it.