NC Error on P2 Trailer Brake Controller when Trailer is Connected

Question:

I have wired the vehicle motorcycle as per the fitting instructions. Minimum wire guage used is 15amp. White wire is direct to negative on battery, black is direct to positive on battery, red is clamped into stop light wire in 7pin trailer connector, and blue goes to pin #5 on the 7 pin trailer connector. When I apply the brake, the red wire has power at the brake controller and activates the brake lights on the trailer. Continuity check with the white wire, at the controller plug, is successful on the motorcycle and the trailer, ie it is earthed. Power check for black wire is successful, showing 13.2volts. Continuity check between the active and earth, with trailer disconnected, is successful. Continuity check on trailer earth to the trailer frame, while disconnected from bike, failed. The same trailer connected to my Mazda MX5 Miata in the US with the same wiring set up, but using a Voyager rather than a P2, works correctly. All of the above tests were the same result for the Miata.

asked by: Bruce A

Expert Reply:

The blue wire for brake output is supposed to go to the pin labeled 2. Or if you are looking at the back of it where the wires attach it is in the 7 oclock position. This is on a 7-Way blade style connector. On a 7-Way with round pins the brake output pin is the center pin. When NC shows up on the P2, # 90885, it means that the blue wire is not sensing the brake magnets. If that output wire is not attached to the correct pin that would be why.

The red wire for the brake controller is the input wire telling the controller you are stepping on the brake pedal so it should have power when the brake pedal is applied and it should activate the brake lights on the trailer (this is actually required by law in California, fun fact).

The Voyager # 39510 only has an LED indicator light, not a display, so if there is no trailer connected then the light would not be green. Once a trailer is connected you should have a green light.

expert reply by: Michael H