Adding a 4- and 7-Way Trailer Connector to a 2003 Ford F-150 with Factory 4-Way Flat Connector

Question:

Ive got a 2003MY F150 Supercab 4x4 with factory trailer tow and flat 4 electrical connector. Can I use this wiring kit with your: 7- and 4-Pole Trailer Connector Socket w/ Mounting Bracket - Vehicle End Item # HM40975?

asked by: John

Expert Reply:

Yes, since your 2003 Ford F-150 came with a factory 4-Way flat what I recommend in order to have both a 4- and 7-Way connector is to first install # 118242, like you said, which comes with a harness that will tee in with the existing harness on the truck. It also comes with the fuses and relays to make the 7-Way functional.

Instead of using the 7-Way only that is included though you would want to add # HM40975 like you said.

Another option is to use # HM40975-11998 instead of 118242 with HM40975 but that will require some hardwiring and you will need to obtain the fuses and relays from Ford. But what you would do is use a circuit tester such as # PTW2993 to test the 4-Way wires to determine the functions and then attach them to the harness in HM40975-11998 based on the chart showing its wire functions located on the product page.

On the truck if you follow the 4-Way harness forward on the underside of the truck it will plug into another harness that continues towards the front of the truck. If you pull back the covering on this forward harness there should be a couple of extra wires not connected to anything. Blue is for brake output for electric trailer brakes and orange is 12 volt power.