Troubleshooting Replacement OEM Tow Package Wiring Harness # 118242 on a 2000 Ford F-150

Question:

Hello - 2000 Ford F150 - installed 118242 to change from factory 4 pole to 7 pole. After install, trlr has no rt brake, signal, or 4 way function. Trlr lamp bulbs are functional. Truck lamp functions are unaffected. Just no rt trlr brake, signal, or 4 way. Parking lamps are functional. Any ideas? Any help would be appreciated. I cannot get the trlr inspected as is. Many thanks,

asked by: Kirk S

Expert Reply:

The best way to determine where the issue is occurring would be to test the 7 pole plug with a circuit tester, without the trailer connected.

Have a friend sitting in the cab press the brake pedal and engage each of the turn signals while you test the corresponding prongs on the plug. If you are correctly receiving power at the 7 pole plug, you will need to turn your attention to the trailer. If not, I would check the connection point between the # 118242 harness and your vehicle, to make sure that there is no debris inside the plug preventing a full connection on any of the pins.

If you discover that the plug on your truck is receiving power as it should be, I would begin by checking the ground wires on your trailer. The trailer connector, any electric brake magnets, and all trailer lights will need to be grounded to ensure that they will function properly.

I would also check your brake and turn signal wires along the trailer to make sure that there are no pinched or exposed points that might be coming in contact with the trailer frame. The brake and turn wires would be yellow for left, and green for right.

You can see a typical trailer wiring schematic at the link provided.

expert reply by: Sarah L