Troubleshooting Erratic Trailer Braking with New Tekonsha Prodigy P3 Controller Installed

Question:

I purchased a Tekonsha P3 a few months ago. Brand new trailer, 11,000 gooseneck, with Dexter axles, never adjust brakes, new wiring harness, and I ground down to bare metal with dielectric grease on the ground. Everything checks perfect with a tester. When I brake I get erratic results. If I used the brake 50 times I got 5 that were great braking events. Most got little to no assist from the trailer brakes and a bunch where I got way too much assist. I got a lot of fluctuation in the voltage out put from the P3 regardless of how hard I was applying the brakes. I set things up like the manual said and tried all three boos settings. The only time the boos setting worked was when I was on the interstate and used boost 1. Boost 2 and 3 gave way too much assist. Suggestions, comments? Please help!

asked by: Doug

Expert Reply:

I first recommend checking the Tekonsha Prodigy P3 Brake Controller # 90195 itself. You can check the output voltage at the rear of the controller by cutting the blue wire 5 to 6 inches behind the controller. Test the wire with a multimeter like # PTW2979 when activating the brake controller. When you read the output voltage coming from the controller, there should be between 12-13 volts when activated. If there is a fluctuation or a large drop or spike in the voltage, then the issue may be with the controller itself which would need to be replaced.

If everything checks out fine, I then recommend going to the brake magnets on your electric brake assemblies. You can use the same multimeter to check the amp draw they are getting. I have attached an article that explains in detail how to test brake magnets on a trailer. Depending on the amperage, it's possible the magnets simply need to be replaced.

Lastly, check to make sure you do not have any shorts in the wiring. Look for any damaged or exposed area of wiring along your trailer that might be making contact with bare metal or a neighboring wire.

If you are still having issues, please let me know and I will be happy to look into this further.

expert reply by: Chris R