Can a 3-Wire to 2-Wire Trailer Wiring Harness Converter be Bypassed

Updated 12/26/2013 | Published 12/23/2013

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16 Gauge Primary Wire - Black - Per Foot

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Question:

can i by-pass a 3 to 2 wire taillight converter in any way

asked by: Kyle

Expert Reply:

The only way to bypass a 3-wire to 2-wire trailer wiring harness converter (assuming your vehicle has a 3-wire or separate tail light system) would be to convert your trailer to a 3-wire (or separate) tail light system. This means you will need a separate tail light circuit, brake light circuit, and turn signal circuits on the trailer. You will also need to use either a 5-way, 6-way or 7-way style trailer connector on your trailer and tow vehicle and substitute one of the pins for the additional brake light circuit.

Keep in mind, this would be a custom setup. You will have to hardwire each of the wires from the trailer connector you choose to use to the tail light circuits on your vehicle. You may also wish to consider the fact that the tail light circuits on your vehicle will not be protected from possible shorts on the trailer. The converter boxes that come on trailer wiring harnesses like part # 119178KIT, have built in circuit protection.

Most trailers use a 2-wire (or combined) system meaning the turn signals and the brake lights run on the same wire. To prevent the need of any additional modification, a 3-wire to 2-wire trailer wiring harness is recommended. It is also the easiest route. If your trailer uses a combined light system, you will have to run new wires for the brake lights the length of the trailer. You will also have to install new tail lights that include a separate brake light bulb.

If you still want to go with a 3-wire setup, you will want a vehicle end and a trailer end 5-way connector like part # HM47890 and the appropriate lengths of 16 gauge wire, # 16-1-1, to make your own 3-wire trailer connectors. The blue wire that is typically used for a reverse light circuit on these 5-way connectors will just need to be spliced into your vehicles brake light circuit. On the trailer side, you will run the blue wire to your new brake lights.

expert reply by: John H