Troubleshooting Brake Controller that Causes Trailer Brakes to Lock Up and Turn Signals to Not Work

Question:

I have a 2004 F150, just bought a 2000 2 horse bumper pull ponderosa horse trailer. I took the truck and had the dash electric brake controller installed, when I hooked up the trailer and started to haul to set the brakes, the brakes locked up. I hooked it to a F 250 with the dash controller and it did the same thing. What could be the problem? The wiring on the trailer. The wheels turn fine when not connected. Also the running lights work but not the brake lights or either blinker.

asked by: Susan

Expert Reply:

What you are experiencing is a common problem. Does the truck have a 7-Way connector and the trailer has a 6 way? If so, and you have used a 7 to 6-Way adapter to make the connection, the problem could be the adapter.

There are two possible ways to wire the 6-Way connector. One uses the center pin as the brake lead, the other uses the center pin as the 12V lead. What is occurring in your case, is that the adapter is applying the 12V to your brake lead, thus locking the brakes every time the trailer is hooked up. We offer a Universal Adapter, part # 47549, that can be wired either way.

The problem with the lights is a separate issue. Did the lights malfunction when the trailer was hooked up to the other truck? If so, the problem is with the wiring on the trailer. You will have to trace the turn/ brake light wires typically the green and yellow wires back from the connector. Look for broken or pinched wires or corroded connections. If the lighting problem only occurs when the trailer was attached to the one truck, check the fuses under the hood that manage the towing circuits. Please check your vehicle manual for more about the fuses.

expert reply by: Mike L