Using Tow Ready # 118158 Converter to Install Third Brake Lamp on Trailer

Question:

I want a separate third light on trailer. I wired the left and right yellow and green to the input. I wired the red wire to the third light and left the left and right output disconnected. I get no output on the red wire wiring this way. According to the instructions with the 118158, the red wire is attached to a wire coming from the brake light switch on the towing vehicle. Please advise....

asked by: Ray

Expert Reply:

To wire a functional third brake light, a tail light converter such as the one you mentioned would be used.

On the input side, the green wire would tap into the right turn circuit, and the yellow wire would tap into the left turn. On the output side, the yellow and green wires would be capped, with the third brake lamp being fed by the red wire. Make sure the third brake lamp is correctly grounded to the trailer frame either by its mounting bolts or by a jumper grounded to the trailer frame.

If installed as outlined above (see diagram), the third brake lamp should be functional. Since the trailer right and left turn circuits both carry the brake lamp circuit, as well, the converter would separate that signal out.

The converter box isn't meant to be directly exposed to the weather. If you don't have a protected area to install the box, you can use a junction box like part # 38656 to provide necessary protection from the elements.

expert reply by: Mike L