Installing 7-Way Connector on 2004 Ford Expedition with 4-Pole Trailer Connector

Published 01/11/2011

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Question:

2004 Ford Expedition 5.4L with factory 4-pin connector. There is a blue wire taped up within the rear wiring. Can I safely assume that this wire is connected to the factory plug under the dash? If so, I assume that I would only need your 4-pin to 7-pin adapter, the brake controller with this pigtail, and then run a 12V auxillary wire from the battery? I hope this is correct. I am planning to tow a camper trailer and would need the 12V auxillary to charge a battery on the camper. Am I missing anything?

asked by: BRYAN P

Expert Reply:

You are correct. That blue wire carries the output from the brake controller. To convert your 4-pole to a 7-way, use an adapter like part # 37185. The connector on the adapter would connect to your existing 4-pole. The remaining wires would connect as follows; the white wire would ground to the vehicle, the blue wire connects to the blue brake controller output wire and the black wire would be extended to attach to the positive battery terminal using an inline 40 amp circuit breaker like part # 9510. The purple wire is typically connected to the reverse light circuit. If your trailer does not have reverse lights, this wire can capped off and bundled up out of the way.

The 12-volt feed off of the trailer connector can be used to maintain your battery, but be sure to unplug the trailer when the vehicle is not running so that the tow vehicle battery does not discharge. We also offer a battery isolator part # PK5231201 that would prevent the battery from running down by cutting the power to the 12-volt trailer accessory feed when the ignition is switched off. Keep in mind that this circuit won't have enough power to charge a dead battery, but it will keep a battery maintained. When shore power is available, you could use a battery charger like the CTEK # CTEK56353 to recharge the battery.

expert reply by: Mike L