Troubleshooting Trailer Brake Controller Only Activating Brakes When Using Manual Lever

Question:

I have trailer brakes when I manually hit the lever on the brake controller, but no trailer brakes when I hit the brake pedal on the truck. 2020 Chevy 3500

asked by: Todd M

Expert Reply:

Depending on how you are testing the trailer brakes and the controller you have may determine your issues on your 2020 Chevrolet 3500. To begin proportional brake controllers like the Prodigy P3 # 90195 will not always send power to the trailer brakes if it doesn't sense the inertia of stopping. So if you are parked the inertia sensor will not sense braking when you push on the brake pedal. It will send power when using the manual switch without sensing braking inertia.

If this is not the case you will want to check the wire coming from the brake switch. A Test Light # PTW2993 will allow you to see if you have power coming from the brake switch to the controller. If you do not have power coming from the brake switch you will need to verify if you have a damaged fuse or if the switch needs to be replaced. If you have power from the brake switch going into the controller but nothing coming out then the controller is likely damaged. Be sure to check your controller manual to ensure it is installed correctly.

expert reply by: Bud M