Troubleshooting Prodigy Brake Controller Installation on 2016 Nissan Frontier

Question:

I have a 2016 Frontier trim level S. I connected the wiring harness with relays under the passenger side kick panel, connected the brake controller harness to the factory connecter under dash. When the trailer is connected to the 7-way plug, the lights work but the brake controller says NCnot connected. I checked all fuses, fusible links and ensured all connectors were plugged in. What can be the problem?

asked by: Pavel

Expert Reply:

When a brake controller indicates the error message NC ('trailer not connected') this means that the controller is not sensing the electrical resistance of the trailer brake magnets. Causes for this include something as simple as corrosion or trapped dirt inside the trailer connector's contact for the brake circuit, or a loose ground wire at the main trailer harness or at the brake assemblies, or a bad brake magnet. There could also be a short on the brake wire somewhere between the trailer plug and the brakes.

If you have access to another trailer to try this is a fast way to troubleshoot. If the problem disappears you know to focus on the wiring on your trailer. If the issue remains you know that the cause is potentially on the vehicle side.

You can test the trailer brake circuit directly by disconnecting the trailer from the Frontier and applying 12V ground and power direct to the brake circuit. Please refer to the linked photo to see which contacts on your 7-way to use. If direct 12V power input causes to brakes to engage (you'll be able to hear them hum slightly) then you know the trailer is okay and that the issue is on the vehicle.

If you have a circuit tester like # PTW2993 you can also test the vehicle without the trailer connected. Apply the tester to the brake circuit while a helper presses the manual override to see if a signal is present.

Since all your lights work and the brake controller has power, it is more likely that the issue is in the brake circuit on the trailer side. Trace the brake circuit wire (usually blue) to check it for cracks or worn spots on its insulation and repair or replace as needed.

expert reply by: Adam R