Troubleshooting Brake Controller Getting Hot on 1993 Ford F-250

Question:

I have a Tekonsha Envoy electric trailer brake controller that Id like to install in my 1993 Ford F-250. The truck has a factory installed wiring harness for an electric trailer brake controller located under the ash tray. Both the harness and controller have four wires: black, red, white, and blue. From what I have found online, I have connected the controller black wire to the harness red wire to power controller and the controller red wire to the harness green wire to engage the trailer brakes when the truck brake pedal is pushed. I also read that the white wire should go to white and the blue to blue but this doesnt work. If I connect the controller blue wire to the harness white and the controller white wire to the harness blue the light on the controller comes on green and when the truck brake is pushed the controller light turns red. So it seems like this is the correct way to wire the unit except that the controller gets very hot to the touch. What am I missing if the blue-blue and white-white connections are correct? If blue-white and white-blue is correct what could be causing the controller to get so hot? Does this indicate a short somewhere?

asked by: Daniel T

Expert Reply:

The four wires coming from your Tekonsha Envoy trailer brake controller will be for the following functions:

White for ground.
Black for 12V power.
Blue for brake output.
Red for stop light switch.

I was not able to confirm the wire colors and their function for the built-in harness in your 1993 Ford F-250. The only way to verify that you have made the correct connections is to simply test them for their function with a circuit tester like # PTW2993.

The fact that the controller is getting very hot does indicate some kind of short. More than likely this is actually coming from the trailer side, particularly the brake output wire. I recommend checking along this wire to see if you can find any cuts or exposed wire that might be causing a short, simply fixing as needed. Also check both the trailer side and vehicle side connectors for any corrosion or rust, as this can also lead to a short.

If you are unable to resolve the issue, please let me know and I will be happy to look into this further. I have also attached a troubleshooting article that you might also find helpful.