Installing 7-Way Trailer Connector and Brake Controller on a 2002 Ford Expedition with Factory 4-Way  

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The 12 volt power wire is present under the vehicle and is already fused so you would not need to hardwire in a relay or anything.

Installing a brake controller and a 7-Way will be pretty easy on your 2002 Ford Expedition, even if it only came with a factory 4-Way. On models that came with the 4-Way flat the plug for a brake controller should still be there. To access the OEM plug, look near the diagnostic port on the underside of the dash. You should see an open-ended, gray plug hanging down near the diagnostic port.

If this plug cannot be found near the diagnostic port, remove the trim panel from below the steering column and look for a gray plug on the right side, near the center console and radio area. With the lower trim panel removed, look for the gray plug beside the sheet metal that runs along the drivers side of the radio area. If it is not readily visible, you may need to check further inside of the dash, reaching through the sheet metal and into the area behind the center console.

Once you have found the factory plug there are a few more steps needed to get everything working and add the 7-Way. For a 7-Way use # 37185. The vehicle 4-Way will plug into this adapter. Then there are just 4 wires left to hardwire into the vehicle.

First, ground the white wire to the vehicle frame. The purple wire is for reverse lights on the trailer. If the trailer does not need a reverse light function you can tape up this wire and stow it out of the way. To make it live you will need to splice into a reverse light wire behind one of the tail lights.

That will leave the black 12 volt power wire and the blue brake output wire. If you follow the factory 4-Way wiring forward under the vehicle it will plug into another harness. This forward harness as more wires going in then coming out to the 4-Way. If you pull back the covering on the harness you should fine an orange wire for 12 volt power to connect to the black wire. There will also be a blue wire to connect to the adapter blue wire for output to the trailer brakes.

With that completed you will need to make some sure the proper fuses or relays are installed under the hood to make everything fully functional. Use the vehicle owners manual or power distribution box lid to find the locations. If a relay is needed you can obtain it from a Ford dealer.

For a brake controller and wiring harness to plug into the port on the vehicle I recommend going with the P2, # 90885, because of its reliability and ease of use. For a harness use # 3035-P.

expert reply by: Michael H

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