Troubleshooting Low Voltage to Trailer Brake Assemblies

Question:

Im only getting about 8.8 volts on the two passenger side tires.Have not checked the other two. Brakes are not grabbing. When I pull breakaway cable , the tires lock up ok. I just installed the new brakes. Do I need more volts at brake assembly..maybe 11 to 12? Gain is set to 10 on controller. Thanks

asked by: JOHN H

Expert Reply:

8.8 volts is definitely not the full voltage that a brake controller should be putting out when set to it's max setting. It should be putting out 12 volts as the max brake setting. If you can adjust the gain up higher on your controller that should get it to 12 volts. If it's already at max setting then you'd want to probe the blue wire leaving the controller with a volt meter to verify what's leaving the controller. If you get 12 volts there then you'll need to make your way back from there to the trailer connectors and then to assemblies to find where the voltage drops off and address the issue from there.

If the controller isn't putting out 12 volts though when you tested the wire at the back of it the problem is the controller and it would need to be replaced like with our P2 part # 90885.

It could also be too thin gauge wire used on either the vehicle or trailer side. You should have 10 gauge wire like part # 10-1-1 for all of this circuit.

expert reply by: Jameson C