P2 Brake Controller Works With Manual Override But Not with Brake Pedal

Updated 04/28/2026 | Published 04/03/2016

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Question:

I have a P2 prodigy brake controller. I wired it up per the instructions when I apply the break with the trailer on the controller still says .c. And the brakes dont come on. If I slide the manual lever they come on great.

asked by: Rob

Expert Reply:

When a brake controller works with the manual override but not the brake pedal that indicates a problem on the red brake controller wire. Check the red wire using a circuit tester such as # PTW2993. It should show power when you step on the brake pedal.

If it does not, then it is either connected to the wrong brake switch wire (if it was a hardwire installation) or there is a blown stop light or CHMSL fuse on the tow vehicle. If you can tell me the year, make, and model vehicle the controller is installed in I can also determine if there are any special circumstances with it.

expert reply by: Michael H

Kyle C.

9/7/2025

Michael H, I have the same issue. P2 controller, worked great no issues for several years. I have power to trailer and manual over ride works but no trailer brakes with pedal. Truck is a 2006 Chevy 2500 4x4.

Steve L.

4/26/2026

@KyleC I have this issue as well. Did you get your issue resolved? If so could you share any insight? I have a 2006 Coachmen RV on a 2005 Ford E450 chassis. I will also note while the manual lever will apply brakes, the brake controller display stays as .c. when the brake pedal is depressed and I’ve confirmed the brakes are not engaging.

Kyle

4/26/2026

@SteveL Unfortunately, I still have the same problem.

Gwendolyn Y.

4/27/2026

@Kyle What kind of troubleshooting have you done so far? A good place to start is at the 7-way. From what you described, it sounds like that’s working since your lights and manual override are functioning properly. Since the issue only happens when you press the brake pedal, the next step would be to check the red wire going into the brake controller. That wire connects to the cold side of the brake switch and sends the signal to the controller when you press the pedal (that’s when it becomes “hot”). It helps to have someone press the brake pedal while you test that wire. Keep in mind, you won’t see a signal at the 7-way during this test because the P2 is a proportional controller—it won’t send output unless the vehicle is moving. If you’re not getting a signal on that red wire when the pedal is pressed, then you may be dealing with a bad connection or possibly a faulty harness.

Helpful Links

faq-brake-control-troubleshooting.aspx

faq-trailer-brakes-not-working.aspx