Trailer Brakes Locked

[mrmhoffman]

Please help...I'm a trailer brake newbie. Just bought my neighbor's horse trailer which has trailer brakes. I pulled this trailer last hunting season with my old 1500 Silverado w/o trailer brake controller...no problems. Since then I traded up to an '01 2500HD Duramax, which I can see it used to have a brake controller before I bought it. Now when I plug into the trailer the trailer brakes lock up. If I unplug, the brakes release. When plugged in, all of the lights, signals,etc work just fine. Where do I go from here? Is it the truck or the trailer? Thanks.

[DmaxMaverick]

Welcome to The Diesel Page, mrmhoffman!

Click on the link in my signature and open "diagrams". There is a trailer wiring diagram that you can use to verify your truck is wired correctly. Sounds like maybe you have a couple wires reversed, and are putting constant 12V to the brake circuit. If your truck wiring is correct, the trailer may be suspect. Also, check under the dash just to the right of the E-brake for a wire harness plugged into the top left of the circuit block. If it's there, be sure the wires aren't connected to each other. If you are not using a brake controller, you can just unplug the harness from the block, but save it for later.

Good luck!

[RVC]

If you have the 6 pin connector, some trailer manufactures put the brake wire in the centre pin
which is where the GM 12v power is placed on the truck. Move the trailers brake wire to the S terminal. If the trailer is a 7 pin it will still require the moving of the brake/stop wire on the trailer.

[Spindrift]

Excuse me for asking the obvious, but is the sensitivity control turned up all the way?

[MIKE MOG]

I HAD A PROBLEM THAT WHEN MY HEAD LIGHTS WERE ON THE TRAILER BRAKES WERE APPLIED. FOUND THAT THERE WAS A BULLETON ON THIS. THE PANEL IN THE TRUCK WAS WIRED WRONG AT THE FACTORY. I REMEMBER THAT I HAD TO SWITCH 1 OR 2 WIRES. LET ME KNOW IF YOU NEED TO KNOW WHITCH WIRES AND I WILL LOOK UP
THE INFO.
MIKE

[DmaxMaverick]

Originally posted by MIKE MOG:
I HAD A PROBLEM THAT WHEN MY HEAD LIGHTS WERE ON THE TRAILER BRAKES WERE APPLIED. FOUND THAT THERE WAS A BULLETON ON THIS. THE PANEL IN THE TRUCK WAS WIRED WRONG AT THE FACTORY. I REMEMBER THAT I HAD TO SWITCH 1 OR 2 WIRES. LET ME KNOW IF YOU NEED TO KNOW WHITCH WIRES AND I WILL LOOK UP
THE INFO.
MIKE This happens when you use a 2001/2002 brake harness on a 2003 or later. They are wired different, but the plug fits.

[arveetek]

Originally posted by RVC:
If you have the 6 pin connector, some trailer manufactures put the brake wire in the centre pin
which is where the GM 12v power is placed on the truck. Move the trailers brake wire to the S terminal. If the trailer is a 7 pin it will still require the moving of the brake/stop wire on the trailer. RVC has hit the head on the nail. The common 6-way plug used on most horse trailers is fairly standard except for the brake and battery charge line wires. They can be wired up either way. I run into this problem all the time, and all you have to do is either swap the wires inside the plug on the trailer cord, or swap the wires on the truck. If you're using a 7-way to 6-way adapter on the truck, the adapter will come apart, allowing you to swap the wires.

Casey

[MIKE WIENER]

Not on the same subject. But thank god for trailer bracks. just last week on my way for a week of R&R. Had to make a panic stop with my 12000# 5er. from about 55mph full brake had that pedel as far as it would go. Anti locks working traler in verg of lock up stoped with about one inch to contact. Not good when a car stops on fry. for no reson and the person in front of you stops 20 cars short of every thing. and dois not look behind to see what is happining.
Just re meber to ajust that controler after instal.

MIKE

[mrmhoffman]

Sure enough....it was the 6-7 adapter with the 12v feed wired into the trailer brakes pin. Swapped the wires and presto. Thanks for all of your input. Next up....brake controller...