Installing a Trailer Wiring Harness on a 2012 Ford Focus

Updated 12/18/2013 | Published 12/17/2013

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16 Gauge, 4 Conductor Bonded Parallel Wire - Per Foot

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T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

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T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector

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Hook Probe Circuit Tester

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Question:

Im confuse on the wire on the tail light can you please help me

asked by: Renny

Expert Reply:

It depends on what wiring harness you are using on your 2012 Ford Focus. If you are using a hardwire harness where you have to find and splice in the wires from the harness to the tail light wiring on the vehicle, you will need to use a circuit tester to find the correct wires on the vehicle.

If you do not have a circuit tester you can use # PTW2993. Have someone sit in the vehicle and go through the lighting functions; turn signals, running lights, and brake lights, while you test the wires behind each taillight.

The yellow wire on the harness is for left turn signal. Brown is for running lights, red is for brake lights. And green will be right turn signal.

Or, if you do not already have a harness you can install one that just plugs in line with the vehicle tail light wiring. For a hatchback use # 118549 and for a sedan use # 118548. I have linked a video for the hatchback harness and instructions for both harnesses. No cutting and splicing or testing to find the correct wires.

These harnesses do require a direct battery connection to power the trailer lights and isolate the power from the vehicle for protection so I have also included a link to an FAQ article with tips on routing the power wire.