Troubleshooting Brake Controller Installation When It Only Works With Manual Override

Question:

P3 brake controller problem. My P3 was installed by a certified mechanic. I get breaking when using the manual lever but nothing with break pedal. Gain setting all the way up and boost set to b3. Note that while braking, if I lightly use manual lever the manual does engage. Im 1500 mi from my mechanic. What testing should I do?

asked by: David G

Expert Reply:

If the # 90195 brake controller works with the manual override but does not work when pressing the brake pedal, that indicates a problem with the red wire from the brake controller.

The red brake wire is designed to attach to the cold side of the brake switch located at the top of the brake pedal under the dash. You want it connected to the side of the switch that only shows power when the brake pedal is pressed. You can use a circuit tester like part # PTW2993 to test the wire.

If the brake controller is mounted incorrectly, that can also cause issues. check the manual for the specifications on mounting the brake controller to make sure it is mounted correctly.

expert reply by: Jeffrey L