Troubleshooting N.C. Error Message on Trailer Brake Controller

Question:

What does it mean when the n.c. He’s always said it up on my controller if the truck is illuminated or there’s no key in the truck with or without the trailer. N.c. Is lit up on my controller with or without the trailer hooked up and if the truck is running or not.

asked by: Jeff

Expert Reply:

When a brake controller like the Primus IQ # TK90160 indicates "n.c." this means something is interrupting the circuit connection between the controller's output (on the blue wire) and the trailer's brake magnets. Lots of things could cause this issue, anything from a bad wiring ground connection at the vehicle or trailer, corrosion on or inside the vehicle or trailer connectors, a bad ground at the brake magnets or simply a damaged or pinched wire.

Since the "n.c." appears on the controller without the trailer connected this tends to suggest the problem is on the vehicle side so I suggest carefully inspecting the Hino's trailer socket and all of the wiring leading to it. Look for cracked or worn insulation on the brake circuit wire (which connects to the 7-way pin at the 5:00 position as shown in the photo. If you need to replace any brake circuit wire use # 10-1-1.

expert reply by: Adam R