Adding 4- and 7-Way Trailer Connector to 2003 Ford F-150, Wiring Electric Utility Winch on Trailer

Question:

looking for a multitow wiring unit for a 2003 ford f150 flareside. has 4 flat connector now. I do not know if it is a factory 4 wire flat. wanting to keep 4 wire flat and have a seven way. Also wanting to know what I have to do to get power back to trailer to run a winch. what size wiring or is it better and more cost effective to add a battery to back of trailer and use power from accessory on 7 way to keep battery charged and then theres the question on how do you wire that. please give corresponding part #s and videos of installations. Thanks

asked by: Rick

Expert Reply:

Lets start with the wiring connector for your 2003 Ford F-150. With a look under your truck we can determine if the 4-Way flat on your truck is a factory plug or not.

If the 4-Way connector is a factory connector, the wiring harness will be connected to the vehicle wiring harness along the driver's side frame, between the back tires and the end of the truck bed. I have attached a photo showing what the connector will look like.

If you find this connector on your truck, you can use the Tow Ready Replacement OEM Tow Package Wiring Harness 7-Way # 118242 to provide the needed wiring for a 7-Way connector. For a connector with a 4-Way flat and 7-Way blade connectors, you can use the Hopkins 7- and 4-Pole Trailer Connector Socket # HM40975. This connector will plug into the harness that came with # 118242.

If your truck does not have the factory 4-Way plug, you will want to use the # ETBC7 kit to hardwire install the 7- and 4-Way connector on your 2003 Ford F-150. The installation instructions for the ETBC7 kit are attached.

To power a winch on your trailer, the best solution is to add a battery to the trailer. You can use the 12V hot lead from the 7-way trailer connector to provide a maintenance charge to the trailer battery when the trailer is connected to the vehicle. The 10 gauge wire, # 10-1-1, from the 12V hot lead will connect to the positive battery post on the trailer's battery.

The winch's power wires will connect directly to the main trailer battery to power the winch. The winch should have instructions on how to wire the winch to a battery. Typically the red wire is connected to the positive post and the black wire connects to the negative battery post.

One of our most popular electric utility winches is the Bulldog Winch 1.5 hp Trailer Winch with Mounting Plate # BDW15017. This winch has a wire rope, roller fairlead, and a 3,400 pound capacity. The winch comes with power unit on the motor that will connect to the trailer battery. The red wire will connect to the positive battery post and the black wire will connect to the negative battery post. I have attached 2 review videos of this winch for you.