Troubleshooting Brake Controller that Shows Not Connected to Trailer Until Light Tester is Used

Question:

When I hook my light tester to the blue break wires the breaks work but when not hooked it say its not connected to the truck

asked by: Tim

Expert Reply:

What I believe is going on is that there is some corrosion on your 7-Way connection whether it is on your tow vehicle or trailer side. This gives you a bad connection and tells you brake controller, like the P2 # 90885, that the trailer isn't connected. When you use a tester it puts more of a load on that circuit which in turn tells the brake controller that a trailer is connected.

Start off by checking your 7-Way connection for any rust or corrosion. Clean it off and apply some dielectric grease like part # 11755. If this doesn't fix your problem then the next thing you need to do is check the wiring for your brake controller circuit and all of your grounds making sure they are in good condition and securely connected.

Let me know if you continue to have problems and I can help you troubleshoot further.

expert reply by: Jon G