Testing For Brake Controller Power To 7-Way Plug

Question:

As far as I can tell, there’s only about 2 volts going to the trailer brakes on my 1978 camper trailer. The magnets are not activating. I don’t know if the problem is in the Tekonsha controller in the truck, or maybe just old wiring going to the brakes. Any suggestions? Thanks.

asked by: Mike

Helpful Expert Reply:

First you need to determine which type of brake controller you have. A time delay brake controller like the Tekonsha PowerTrac Electronic Brake Controller # 39523 will always send the required voltage no matter if the vehicle is sitting still or moving. Whereas the Tekonsha Prodigy P3 Trailer Brake Controller # 90195 is a proportional brake controller and will only send the power to the brakes when it senses the inertia of a vehicle stopping.

If you have a proportional brake controller the vehicle will need to be moving with the trailer connected to test the correct voltage output.

You can test the output of the brake controller directly at the back of the brake controller to determine if the controller has failed or if the wiring on either the truck or trailer is causing your issues.

I have linked an article below that will cover the voltage and amperage that you should be seeing at your trailer connection and it moves into testing the brake magnets. Also be sure to check all your ground wires throughout the vehicle as a loose ground may also cause issues at the 7-way.

expert reply by: Bud M