Trailer Brakes Barely Work With High Output Setting on Tekonsha P2 Brake Controller  

Question:

Helpful Expert Reply:

A professional checked the wiring but what all did he check? To determine if the cause is on the truck side or trailer side there is some testing you can do (or have done if you need to). There is no special equipment needed, just one other person and a multimeter if you have one. If not, you can use # PT89ZR.

The first thing you are going to want to check is the controller. Disconnect the trailer from the tow vehicle. Then sever the blue wire a few inches back from the controller. Use the circuit tester to test the end of the blue wire coming out of the controller. It should show the full power you have it set to when you apply the manual override. If it does not, then either the controller is tilted or turned to one side or there is something wrong inside the controller and it will need to be replaced.

If it checks out just fine then reconnect the blue wire. Then go back to the 7-Way trailer connector on the truck and test the pins for the proper voltage there while someone sits in the truck and applies the manual override. There should only be a slight voltage drop if at all. If there is a big drop then there is a loose connection or break in the wiring somewhere between the controller and the trailer connector.

Moving on to the trailer side, connect the trailer and do the same test as mentioned above except this time test the brake output wire behind the trailer side connector. If there is significant voltage loss then there is most likely something wrong inside one of the trailer connectors. You will want to clean off dirt and corrosion inside and outside of the connectors. Take them apart and make sure there are good connections.

Next you are going to want to inspect the trailer wiring to the brake magnets. You will be looking for any breaks, exposed wires, or loose connections. Repair as needed. For the grounds, make sure the brake magnet grounds are attached to clean and corrosion free bare metal surfaces.

You mentioned adjusting the brakes but if the magnets are going south the brakes are not going to work well. To test the magnets you will need the multimeter. Then you can follow the FAQ article I have linked showing how to test magnets. I have also included a link to our FAQ on troubleshooting brake controllers.

expert reply by: Michael H

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