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Installing 7-way Connector on 2003 Ford Explorer with Factory Tow Package


I have a 2003 Ford Explorer xlt 4dr. with towing package. The brake controller is plug and go. I have that hooked up. But I have only a 4way plug in back and need 7way for RV. How do I connect 7way to towing package?


Expert Reply:

If you'll follow the wiring from your 4 pole trailer connector back under the vehicle, you'll find it plugs into a connector on the driver's side frame rail. Just past where it plugs in, remove the tape or wire loom from the wiring harness. You should see an orange (or red) and a dark blue wire.

The orange wire carries a trailer power circuit from the battery, and the blue wire connects to where you plugged the controller in to carry the braking voltage to the trailer brakes.

You'll need a 4-pole to 7-way adapter like part # 37185, which will plug into your existing 4-pole. The adapter will have 4 wires remaining. The white wire gets grounded to the vehicle frame. The blue wire will connect with the blue wire you found on the frame rail, the black wire connects to the orange wire you found on the frame rail. The purple wire is usually used to carry the reverse lamp signals to the trailer. If your trailer has reverse lamps, you'd tap this wire into the reverse lamp circuit, otherwise, just tape the wire off and bundle it up out of the way.

If for some reason, you do NOT locate the orange and blue wires on the frame rail, all's not lost. You'll just run your own wires using a length of duplex cable, part # 10-2-1, which is sold by the foot. You'll need a length long enough to reach from the trailer connector to the battery, with about 5 feet to spare. You'll probably need about 20 feet. At the rear of the vehicle, attach the black wire from the adapter to the black wire in the duplex cable. Attach the blue wire to the WHITE wire in the cable. Run the cable up under the vehicle, being sure to avoid exhaust, suspension or steering components (anything that's moving or hot.) You'll run the black wire to the positive battery terminal, after running it through a 40 amp circuit breaker like part # 9510. The white wire will run through the firewall (there should be a grommet you can poke a hole through) and to the brake controller. Connect this wire to the existing blue wire exiting the rear of the brake controller.

expert reply by:
Mike L

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