Troubleshooting Trailer Brakes Locked Up All the Time with Controller Not Showing Connection

Question:

When i plug in my 7 way my brakes lock up. I have a Tekonsha controller with the plug in harness for my truck. The controller says no trailer conection but yet I have power back there.

asked by: George

Expert Reply:

What is most likely happening is that you have a short between the brake output circuit on your 7-way and the 12 volt power accessory circuit. When this happens the brake circuit is hot all the time and will apply the brakes all the time.

What you'll want to do is test the brake output circuit 5:00 position for voltage with a circuit tester like part # 3808 for voltage without the trailer connected. If there's voltage there all the time the issue is on the vehicle wiring and is most likely corrosion or exposed wire at the back of the connector. It also can be the wiring of the controller too though. Check to see if the blue and black wires of the controller are shorting out together.

If the voltage isn't there then the problem is on the trailer side of the wiring and you'd need to inspect it and fix as needed.

expert reply by: Jameson C