Trailer wireing,

[Willie]

??? Question for the electricians in the bunch and maybe some special help from the head honcho here........The last 2 or 3 times I have hooked up the trailer lighting plug, the fuse on the truck for the brakes and tail lights blows. I realize there is a short somewhere, but is there any way to test for it without just re wiring the trailer.....My main problem is that the truck and trailer are down the shore and I am back home in PA. How does one test wiring for the short. Thx, in advance Willie 010

[al_e._gator]

Get an ohmmeter and connect one lead to the trailer frame then connect it to each connector pin in turn. You should only have continuity to the white wire/ground pin at the connector all other wires should be open to ground. If you find a short visually inspect that wire for abrasions and check the light socket for damage, corrosion, or shorted excess wire. I have seen the last in many standard trailer lights because of the type of push fit connection use inside the light housing.

[Harry]

Gator has some good info and is on track.

I might also ask, is it blowing the fuse as soon as you plug in the trailer lights , or if you step on the brake pedal ,turn on running lights, or turn signals?


See where I'm going with this? If it's just when you step on brakes,,,etc, you can start with that circuit.

But like Gator said trailer sockets are a big concern and cause a lot of problems. That and bad grounds, but they usually don't make fuse's blow, just make the trailer lights go whacky....

Let us know how you make out, or you can call me if you need to.

[Willie]

I had it plugged together and turned on the headlights. The truck had tailights, the trailer did not. I tried to get the plug tighter and thats when the fuse blew. Come to think of it the brake pedal was never touched. Willie

[Harry]

OK, The headlights were on, and you pushed and twisted the connector to make a better connection right? That's when the fuse blew?

1) Maybe the pin in the connector wasn't lining up right & got pushed into the pin next to it cuasing the blown fuse?

OR

2) If not, I would test the truck connector and identify the "running light" circuit (since you said the headlights were on when it blew)
Once you find which wire on the truck is the running light wire(s) you can see which one on the trailer is the same.
Check that wire for pinch points or loose connection, and bad sockets.........

[Willie]

Thanks a lot for the info. When I get back down I will give it a go then probably give you a call. . Have a meter, but never really used it. Willie............. 010

[Harry]

No problem.
I have a meter too, but a 12 volt test light is all you really need.( I got one of those too)
Give me a buzz and if I am able, I will shoot over and we can get it fixed up for ya....

[Willie]

Oh by the way, Sat. morning I got to working on the trailer and decided to just run the new wireing harness. Just kinda taped it to the outside of the trailer, figured it would hold for a couple of launchings and the trip back to PA. after we did this I needed a 15 fuse for the truck and only had a 20. SOooooooooooI put it in and hit the trailer lights, within 2 seconds had some smoke by the left tailight, then the fuse blew. We found the short. You know the little clips they give you to att the wires to the trailer, well this one had cut through the insulation. after rewrapping that bad piece, all is well and I have lights again. Oh I did replace the fuse with the proper rating this time. 010 010

[Harry]

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