Troubleshooting Single Wire Trailer Marker Lights Only Running On Turn Signals and Brake Lights

Published 10/17/2023

Products Featured in This Question

Optronics LED Trailer Clearance and Side Marker Light w/ Reflex Reflector - 6 Diodes - Amber Lens

(4558)

$6.99

Peterson Piranha LED Clearance and Side Marker Trailer Light w/ Turn Signal - 6 Diodes - Amber Lens

(264)

$21.61

Question:

Hi, Im on a quest...I have a couple sets of single wire lights that I want to install on my utility trailer. I have a flat 4-pin off the vehicle and currently have the same set up on the trailer. My old lights are 2-wire but are busted up. I installed one of the single wire lights and have turn signal and brake lights but no tail lights. How would I get the tail lights to work on a single wire?? Or, I just replace the lights with the LEDs I have and not worry about it.. Haha. Thanks.

asked by: Phil R

Expert Reply:

It sounds like you have some marker lights like the Optronics # MCL44AB1 which was only designed to activate when the running lights are switched on. If you also want the lights to illuminate with turn signals and brakes you would want the Peterson # M353A which has 3 wires. One ground and one for running lights and the 3rd wire for the turn/brake light.

The single wire light you have uses the mounting hardware to ground to the trailer chassis. This would be connected to the running lights wire which is typically brown on most trailers.

expert reply by: Bud M