View Full Version : fuse keep blowing

08-10-2005, 02:51 PM
i keep blowing the fuse for the trailer lights in my trucks fuse box. what causes this and how to fix???

08-10-2005, 03:16 PM
Well, a fuse will only blow for one reason, there's too much current flowing through it. So, one of two things are happening, either there's a short somewhere, or the load was increased somehow. (Did you add any lights to the trailer?) Check the wiring particularly near the front, sometimes a tight turn will pinch a wire and cause a short. Maybe also check near the gate if you have any wires in that area that may have been pinched. Sometimes it's something has hit a wire underneath and done it too.

Which particular circuit is it? If it's brakelights, for example, follow those wires around the trailer.

Of course, I'm assuming that it doesn't blow a fuse when the trailer is disconnected, which isolates it to the trailer.

08-10-2005, 04:36 PM
yea its the brake and turn signal fuse for the trailer lights.what a pain in the ass these light are!!!!!!!!!!

08-10-2005, 04:51 PM
get up under the trailer and look at the wires as they go through the frame . Im assuming that in the frame there are holes cut or drilled that the wire runs through. Check the wires where they go through and make sure they have not rubbed the frame enough to strip the housing off of the wire. This used to happen to me all the time. Now when i get a trailer on day 1 i automatically get under it and wrap the wire with electrical tape to prevent this. Its an easy repair. Just wrap the exposed wire with electrical tape and off you go. IF this is found to be true on your trailer while you are already under the trailer go ahead and wrap the other places and wires as well so that it doesnt occour again and cause more down time. Let me know if you need anymore info......... You know i heard froma trailer repair shop that duringthe average 10 year ownership lifespan a trailer the wires are repaired/replaced an average of 7 times. What a PITA.

08-10-2005, 08:19 PM
i plant art:
i never heard that before. i ll check that out 2morrow and see whats up. hopefully that will fix it


08-11-2005, 12:38 AM
Check your ground connections at the trailer brake/turn lights..Nine times out of ten this problem stems from corrosion/junk build-up where the light is grounded at the trailer. Pull the lights off (ground is often underneath the light) take the ground loose, sand/grind trailer to bare shiny metal at the connection point, and re-install the ground using a stainless star-type washer between the bolt and trailer.


08-11-2005, 12:44 AM
vaham- tghe fuse wont blow from junk/corrosion around the connector.... it just simply just wont work.------ crawl around it will fix the problem 10 out of 10 times....... i cant tell u how many times ive done this for people....... its the last thing that someone ever thiks of/ does just simply b/c it doesnt cross their minds.

08-11-2005, 01:07 AM
You are DEAD wrong !!!

If you do not have a good ground connection at the trailer lights, then when your turn signal is on, the harness is forced to "pull" ground through the unenergized brake light feed, which works okay until you tap the brakes, energizing the line and blowing the fuse... If you are so educated as to 12v electrical systems, why don't you know this ?

08-11-2005, 01:16 AM
I've also used a short piece of hose 'slit' along the side to wrap wires that are rubbing (assuming there's room), either tape it at the ends, or sometimes some cable ties will hold it in place. In reality, trailer lights aren't real difficult to fix, the problem is that they are extremely time consuming. (So, for you solo guys, this is something that can cost a lot to have repaired, or cost you little if you have some time available now and again.)

I now keep a supply of stainless steel nuts/bolts washers for mounting trailer lights and ground connections with. I also use anti-seize where ever I can. (Have to remember that my trailers are often exposed to salt in the winter time.)
I also solder all connections possible, and seal with heat shrink tubing. A little general purpose grease on the base of bulbs helps cut down on corrosion.

Remember, there are only 4 common circuits on trailers.
Taillights/clearance lights
Left brakelight/turnsignal
Right brake light/turnsignal
Electric brakes

A test light is your best friend on these repairs. Use it to help isolate the problem areas. (I also keep a roll of wire around with an alligator clip on one end to ground, long enough that I can use the same ground point to test all lights.)

08-13-2005, 03:14 AM
bobcatnj- so did u get it fixed.. what was the problem/solution?

08-13-2005, 09:32 AM
no i checked the wires and put tape where the wires go through the trailer underneath. still no luck. its been way 2 hot these past couple days to mess around with it and get a pissed off over the damn lights. maybe i'll just re wire it again