Truck Lights Stay On with Hayes Brake Controller Installed

Question:

have not installed electric trailer brakes. the only way I can cut off lights is to pull the 2 10 amp fuses under the hood. I put new column switch and that didnt help. Even with the truck turned off the work.

asked by: Bert M

Expert Reply:

If this issue started happening after installing the brake controller, then it could be a missed connection in the wiring or a problem in the brake controller. If you can tell me the year, make, and model of the truck I may be able to pinpoint the exact issue.

On a brake controller, the white wire is ground, black is 12-volt power to the controller, blue is output to trailer brakes, and red is input from the brake switch. If the brake controller is putting out voltage on the red wire or it is connected to the wrong wire, then it could be back feeding to the truck brake lights.

Use a circuit tester, # PTW2993, to test the red wire connection. If there is voltage on it, then that would light up the truck brake lights. If you disconnect the red brake controller wire and the problem goes away, then the issue is with the brake controller, and it will need to be replaced. If it keeps happening even with the brake controller disconnected, then the issue is with the truck wiring most likely a short or corrosion in a connector or wiring somewhere that you will need to track down.

The red wire needs to attach to the cold side of the brake switch located above the brake pedal on most vehicles. Use the circuit tester to probe the wires until you find the one that only shows power when the brake pedal is pressed. If the wire also shows power with the headlights or turn signals on, then it is not the correct wire.

I have included a link to our FAQ article on troubleshooting brake controllers for you.

expert reply by: Michael H