NC Error Message on Trailer Brake Controller Installed on a 2006 GMC Sierra Duramax Diesel

Question:

I have the Prodigy P2 Electronic Brake Control on my GMC pickup and the trailer brakes are not working. I get the NC error message when I connect the trailer and actuate the trailer brakes with the truck running. I have searched for loose grounds, shorts, and in-line fuse problems with no luck. I also connected the trailer to another truck with a different brake control and the brakes would not work on the 2nd truck. Because the trailer brakes do not actuate when connected to two different trucks I believe there must be a short in the trailer which is blowing the fuse in the truck. Am I correct? Is there an in-line fuse between the Prodigy controller and the connector at the rear bumper and if so where is it located. Any information you can give me on possible causes would be much appreciated. Thank you for your help.

asked by: Terri C

Helpful Expert Reply:

First, check the trailer side connector for any dirt and corrosion and clean it out. Corrosion can also build up at the back of a connector where the wires attach, You referenced part # 90885 and the wiring adapter # 3020P but the 3020-P connector is not correct for a 2006 GMC Sierra. You would need to use # 3015-P.

To test the trailer, after making sure the connector is clean and corrosion free, make sure the main ground is attached to a clean and corrosion free bare metal surface. Then check the brake magnet wiring for any nicks that may be touching bare metal. The magnet grounds should be attached to clean and corrosion free bare metal near the magnets.

Visually inspect the magnets next. If you can see the copper windings coming through then the magnets will have to be replaced. I have included a link to an FAQ article that explains how you can further test the magnets.

You will also want to make sure that all the connections are made under the hood of the truck. I have included a link to an FAQ article that covers this. There are fuses under the hood that you will need to make sure are in place and not blown. The FAQ covers this as well.

With the proper connector installed and all the under hood connections in place and with good fuses, you can further test the brake controller using a circuit tester # PTW2979. Sever the blue wire a few inches from the back of the controller. use the circuit tester on the end coming out of the controller. It should only show a signal when the manual override is applied. If it shows power at any other time then there is something wrong inside the controller and it will have to be replaced.

If the controller checks out then make sure the truck connector is clean and corrosion free as well and use the circuit tester to make sure power is getting back to the connector while someone applies the manual override. If it is not then either those underhood connections are not made or there is a break somewhere between the controller and 7-Way you will have to track down.