Trailer Brakes Are Weak Using 8 Year Old P3 Brake Controller

Question:

My P3 controller is 8 years old. Worked just fine until recently. Now brakes travel trailer poorly. New brakes recently installed on TT. With trailer unhooked I Set output voltage to 12. I push hard on brake with Tekonsha controller troubleshoot feature engaged to find: Battery = 14.2, Brake = 14.2, Voltage out =3.2, Current out = 0. When I hook up travel trailer I get similar reading expect current = 3.2. When I use manual switch engaged fully, I get voltage out =12.2. Im guessing my controller is faulty. Do you agree?

asked by: William F

Helpful Expert Reply:

The P3 brake controller is not going to send back any power to the brake magnets unless the vehicle is moving and a trailer is connected. The output current of 3.2 amps to a brake magnet is within normal operating range for 7 inch to 12 inch brake assemblies.

Usually the first thing to check is the brake adjustment. The old brakes weren't braking like they used to so you replaced them. New brakes require an initial adjustment, even if they are self-adjusting brakes, or the braking will be weak. If you haven't adjusted the brakes then that is likely the issue.

You can use a screwdriver to adjust the brakes but a brake adjusting tool, # W80630, makes it much easier. To see how to manually adjust trailer brake assemblies check out the video I attached, fast-forward to the 4:35 mark of the video.

You can also test the brake controller. I have included some links on testing and troubleshooting brake controllers if nothing else above ends up working out.

expert reply by: Michael H