Can a Third Brake Light Be Added to a Trailer

Question:

Hello, I have a unique wiring problem that Im trying to work out for my towed RV. In addition to the two existing Stop/Turn/Tail lights, I want to add a third brake light to the rear of my towed RV. This is effectively a center mounted, dedicated brake light. My tow vehicle has the typical signal and brake lights combined. Is there an appropriate converter available to do this? If not, can I just tap into the electric brake wiring to turn on the brake light? Light is LED. Thanks for any help you can provide.

asked by: Rod C

Expert Reply:

To add a third brake light to a trailer is pretty simple, but does require an adapter to convert the signal.

Because trailer tail light systems combine the stop lamp and turn signals for each side onto a single circuit, you will need to use a vehicle-to-vehicle tail light converter, part # 118158 to split the brake light circuit back out.

The white wire on the input side of the converter would ground to the trailer frame, the green input wire would tap into the right turn circuit on the trailer and the yellow input wire would tap into the left turn circuit. For quick splices you could use the part # SWC501746-1. The output side of the converter also has three wires. The yellow and green wires are not needed for this application, and could be cut short and should be capped off. The red wire would connect to your third stoplight, with the light also grounded to metal on the trailer frame.

Looking at the diagram I produced for you will give you a good idea of the wiring layout.

expert reply by: Jameson C