Recommended 4-Way Trailer Wiring for 2002 Ford E150 Van

Question:

No trailer lights working. Weak signal from van side 4 way plug for RT green and LT yellow, strong for running brown - using 4 way light plug tester. The indicator lights for RT and LT on the tester only work if plug is partial disconnected and twisted some. Strong signal from all three green, yellow, brown connections when using probe tester connected to white wire ground on plug. No signal when probe tester connected to good vehicle frame ground. No power to trailer RT and Trailer LT fuses in fuse box under hood. Fuses not blown, just no power.

asked by: Richard

Expert Reply:

For your 2002 Ford E150 Van, the relays and fuses only make sense when you have the factory 7-way. When you don't have the factory 7-way, then you need to use a different wiring harness to get your features. Since you have a 4-way it is very likely that the connections are spliced into your factory wiring and there may be a connection issue there. You can use a circuit tester like # PTW2993 to probe each wire and you should have power and correct function when using a good vehicle frame ground.

I recommend the T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector # 118344. This will give you the functions you desire and is easy to connect to the factory wiring harness connections behind your tail lights.

expert reply by: Jason S