How to Separate Out Running and Brake Combined Signals on a Multiplex Wiring System
Updated 09/12/2025 | Published 08/23/2025
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Question:
Hi, I have a question about tail light wiring. I’m trying to wire separate LED brake and turn lights on my vehicle and my vehicle already has a separate turn signal wire and a combined brake/running light wire. However, the LED lights each have three wires turn, running, and ground for the amber turn light. Break, running, and ground for the brake light. How would I go about splitting the brake/running light wire from my vehicle to connect it to the LED lights?
asked by: Benjamin L
Expert Reply:
Hey Benjamin, thanks for reaching out!
It sounds like your vehicle has multiplex wiring so you need the ZCI Circuit Protected Vehicle Wiring Harness w/ 4-Pole Flat Trailer Connector and Installation Kit # 119250KIT. This takes all of the needed wiring circuits and splits them up into the standard trailer wiring 4-Way flat connector:
- Running
- Ground
- Left Stop/Turn
- Right Stop/Turn
The Curt 2-to-3 Tail Light Converter # C56196 will then allow you to separate out the brake and turn signals, but the Curt converter isn't designed for LED lights so you'll also need the Load Resistor Kit # DI34ZR so the LEDs will have enough power pull for the converter will work correctly.
Does this sound like it will do what you need it to do?
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Jon G.
9/12/2025
Hey Benjamin, did the wiring harness and converter setup work out for your LED lights? I'm asking because your experience could really help others with similar wiring challenges.