Could the Optronics Trailer Light # STL69RB Be Used as a Third Brake Light on a Trailer

Published 12/30/2014

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Question:

I have a 2003 4Runner that has a brake controllerinch wire included in the 7 blade round connector that I have continued through in my trailer wiring small 5x9foot utility trailer. Can I use that wire to power this light as a 3rd brake light that only illuminates upon braking? In other words, shouldnt the brake controller wire activate or provide power only when braking such that it would be useful for this purpose?

asked by: Todd F

Expert Reply:

The brake output circuit of your vehicle/trailer wiring wouldn't be an ideal circuit to power the third brake light of a trailer unless you wanted to modify the circuit on your tow vehicle. You would have to run a brake light circuit straight to the brake output circuit so that the pin sees 12 volts when the brake are applied. Trying to run the output from a brake controller to a third brake light wouldn't be a feasible option. A brake controller won't send a full 12 volts to the output circuit of the 7-way immediately when the brakes are applied so it wouldn't work.

From there you would need to run a wire from the brake output circuit of the 7-way on the trailer to the black wire of the # STL69RB.

An easier and more recommended method would be to use a taillight converter to isolate the stoplight circuit like part # C56196. See the chart I attached to see how it wires in.

expert reply by: Jameson C