Electric Trailer Brakes Not Working on Trailer and 1995 Ford F-250 but Will Work on Other Vehicles  

Question:

Expert Reply:

Check the pin for electric brakes on the 7-Way, vehicle side connector with no trailer attached, using a circuit tester like # PTW2993, to make sure a signal is getting sent to the plug. If you are looking at the plug, it should be the bottom right pin. Test it with someone pressing the brake pedal, and then when using the manual override.

If it is not showing a signal at the plug, then something is amiss between the brake controller and the plug, most likely a short or broken wire. You can also check for output from the brake controller by probing the blue wire while pressing the brake and then the manual override. If there is no signal coming from the blue wire then there is a problem with the internal circuitry of the brake controller, and it will need to be replaced.

The brake controller should be wired with the white wire connected to the negative battery terminal, the black wire connected to the battery via a 20- or 30-amp fuse (see break controller instructions for which size to use), blue wire connected to electric brake output on the 7-Way, and the red wire connected to the stop light wire on the brake switch.

If you do find it is working properly, connect the trailer and check for a signal in the electric brake wire behind the trailer side plug. If there is a signal, then you will need to check the brakes themselves to make sure the magnets are not worn and in need of replacement. But since you mentioned it works on other vehicles, the brakes probably are not the problem.

It could be that the 7-Way on the truck is pinned differently than the trailer and you will need to re-pin it to match the functions on the trailer. The most common wiring method can be found about halfway down the page of the wiring FAQ article you have referenced.

expert reply by: Michael H

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