Troubleshooting Trailer Brakes Not Fully Engaging

Updated 05/09/2023 | Published 05/06/2023

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Question:

I just installed brakes, 10inch self adjusting brakes on my trailer. Re wired the trailer and added a junction box for the 7 pin. Everything works except the brakes do not fully engage. I have 10.6 volts at the axle. When I set my brake controller to 10 I can feel resistance but it will not slow my truck. Adjusted the brakes, tires wont spin a full rotation. Checked the voltage, 10.6v. 13.6 at the truck hitch. Its a factory ford controller f250 2006.

asked by: Bryan

Expert Reply:

There are a couple things you can try to troubleshoot this issue. Since you have full power at the rear of the truck it is safe to say we can rule that out. I would start by checking the ground connections for your trailer brakes. Make sure they are secure on a clean, bare-metal surface. If you don't have a ground for each brake assembly I recommend grounding them individually.

The other thing you can check is the brake output wire. You want to at least have 10 gauge wire like the # 10-1-1. This will help as the power travels the length of the trailer and to the different brake assemblies. I'm not sure if you have 2 or 4, but the more you have the more voltage will be lost as it travels to the brakes.

I know you said you adjusted the brakes, but make sure you also break them in. I also wouldn't advise trying to manually adjust them. Drive your trailer in an open parking lot and speed up to 40 mph and apply the manual override. Doing this 20-30 times will properly seat the brakes. This will also help get them properly adjusted. Allow time for your brakes to cool during this process.

expert reply by: Robin H