Troubleshooting Brake Controller and Trailer Brake Issues

Question:

I have a 2007 jeep jk and installed 7-Way Trailer Tow Hitch Wiring MOPAR GENUINE OEM NEW - Mopar 82210214AB yrs ago. I rebuilt a m101a3 trailer and it has Dexter 3500 axle with electric brakes. I have a promise IQ control which is mounted flat on dash. All lights are working. The controller shows numeric numbers when applying brakes. Issue is the brakes aren’t working. I used the manual override on the controller and even with turn all way up they aren’t working. So far I adjusted brakes, tested brake controller harness and the 7 pin. I used an old screw driver type wire tester. I noticed the light is dimmer at the 7pin then on the brake controller harness. I can hear a hum from the brakes when they are applied sitting still in my driveway.

asked by: Eric B

Expert Reply:

If you are testing at the 7-way and everything tests fine, then the problem isn’t on the Jeep it’s on the trailer.

If you are testing at the 7-way and it’s not good, then you need to test about 10 inches after the controller. If it’s good there, then the problem is between those points on the blue wire. If it’s bad there then the controller is shot.

If it is the controller I recommend the Tekonsha Prodigy P3 Trailer Brake Controller # 90195 which is a proportional brake controller as a replacement.

If everything is fine on the Jeep, you should test for power at the brakes when using the manual override. If you get full power there, then you need to adjust the brakes more. If not then the problem is between the brakes and the trailer’s 7-way.

expert reply by: Scott S