Troubleshooting Lack of 12V Power to Electric Trailer Brake Controller on 2004 Freightliner XC

Question:

I have a 2004 Mandalay 40-B which sits on a Freightliner chassis. I have found the connector and ordered the harness for my P3. the harness has never been used before. is there a typically a fuse in the motorhome that needs ed or does it usually always have power? I installed the harness and the P3, started the coach and no power to the P3.

asked by: Larry S

Expert Reply:

The Tekonsha Plug-In Wiring Adapter for Electric Brake Controllers # 3027-P is the correct wiring harness for your 2004 Freighliner XC Chassis. I recommend removing the harness and testing the pin with a circuit tester like # PTW2993 where the black wire connects to give power to your brake controller. If you don't have power at that pin, then I recommend checking your owners manual for fuses and relays. Unfortunately we don't have wiring schematics or owners manuals for every vehicle, so I can't provide that, but I can help with testing techniques and a work around option.

If you can't pin point a fuse location, then you can either trace the wiring probing every few feet to determine if there is a short, or you can splice into that wire and use # 10-1-1 wire and a circuit breaker like # 9506P to run that power wire from the battery to the circuit breaker and then to that pin location.

expert reply by: Jason S