Troubleshooting Trailer Brake Controller Where Brake Pedal Does Not Send Voltage To Trailer Brakes

Question:

When I press my brake pedal to stop my trailer I do not have any voltage on my blue wire. When I slide and activate my brake controller manually I have voltage on the blue wire. Could this be a faulty controller or possibly a faulty brake switch.

asked by: Ken C

Expert Reply:

First things first do you have a proportional controller? If so it senses movement of the vehicle to match the braking intensity to the trailer brakes so if you are sitting still it may not send any power on the blue wire by pressing the brakes.

If you have a time delayed controller than it is likely the wire running from the the trailer brake controller you have installed to the cold side of the stop light switch is incorrect and not getting the correct signal to apply the trailer brakes.

The red wire from the brake controller is the wire that connects to the cold side stop light switch wire. I recommend using a circuit tester like # PTW2993 to verify that the red wire is connected to the cold side of the stop light switch that only has power when the brakes are applied. It is possible that the stop light switch is bad, but that would also cause the brake lights on your vehicle to not be working.

If the wire you are connected to does have power only when the brake pedal is pressed, I recommend double checking that the connection to that wire is secure and did not come loose.

It is unlikely that this issue is due to the controller being faulty, but if using the circuit tester you find that the wiring is correct yet the controller is not applying the trailer brakes it will need to be replaced.

expert reply by: Samuel C