What To Do When The Brakes Only Work When Manual Override Is Applied  

Question:

Expert Reply:

If you have a proportional brake controller, the unit will only send around 1 volt of power to the trailers brakes while using the brake pedal when the vehicle is not in motion which is not enough power to engage the brakes. Proportional brake controllers have an internal sensor that sends the correct amount of braking force that needs to be applied to the trailer based upon the vehicle's braking when using the brake pedal. If you are testing this at a standstill, then the brakes on the trailer will not engage. They will only engage with the manual override.

If you have a time delay controller, it sounds to be like you may have the incorrect stoplight wire connected to the controller's red wire. In order to test this, you will need a circuit tester like part # PTW2993.

The first thing you will want to do is check that the OEM factory stoplight wire connector to the brake controller is only getting power while the brake pedal is pressed. There may be both a constant and intermittent brake wire in the factory harness, therefore you will need to determine you have located the correct wire by pressing the brake pedal and checking to see which wire only receives power when the brake pedal is pressed.

The brake light wire will be different from vehicle to vehicle therefore you will need to use the circuit tester to determine this. The correct wire coming from the brake controller that will need to be spliced into the factory stoplight circuit is the red wire.

I have also attached our brake controller troubleshooting guide for your review.

expert reply by: Conner L

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