How to Separate Out Running and Brake Combined Signals on a Multiplex Wiring System
Updated 09/12/2025 | Published 08/23/2025
Products Featured in This Question
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?
Product Page this Question was Asked From
ZCI Circuit Protected Vehicle Wiring Harness w/ 4-Pole Flat Trailer Connector and Installation Kit
- Custom Fit Vehicle Wiring
- Trailer Hitch Wiring
- Vehicle End Connector
- Converter
- Universal Fit
- 4 Flat
- Plug and Lead
- Plug-In
- Hidden
- Tekonsha
more information >
Featured Help Information
Instructions
Continue Researching
- Shop: Trailer Wiring
- Search Results: trailer hitch
- Shop: Trailer Mate Trailer Hitch Receiver - Custom Fit - Class III - 2"
- Search Results: power converter
- Shop: Trailer Hitch
- Search Results: tail light converter
- Shop: Roadmaster Brite-Lite 3-to-2 Tail Light Converter for Towed Vehicles
- Shop: Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
- Q&A: How to Get Separate Turn Signals and Brake Lights to Work on a Trailer
- Shop: Curt 2-to-3 Tail Light Converter for Towed Vehicles w/ Incandescent Tail Lights
- Shop: Curt 4-Way Flat Trailer Connector with Circuit Protected Powered Tail Light Converter
- Shop: ZCI Circuit Protected Vehicle Wiring Harness w/ 4-Pole Flat Trailer Connector and Installation Kit
- Shop: Load Resistor Kit for LED Turn Signals - 50 Watts - 6 Ohm - Qty 2
- Article: Brake Controller 7- and 4-Way Installation Kit (ETBC7)
- Q&A: What is the Difference Between a 4-Way and 7-Way Trailer Connector
- Article: Trailer Wiring Diagrams
- Q&A: What is the Difference Between a Class II and a Class III Hitch?
- Article: Wiring Trailer Lights with a 7-Way Plug (It's Easier Than You Think)
- Article: Wiring Trailer Lights with a 4-Way Plug (It's Easier Than You Think)
- Article: How to Choose the Right Trailer Hitch Class
- Article: How to Measure for Trailer Hitch Drop
- Q&A: Troubleshooting ZCI Vehicle Wiring Harness 119250KIT Having Inconsistent Right Turn Signal Flashing
- Article: Brake Controller Installation: Starting from Scratch
- Q&A: Trailer Wiring Options For A 2025 Chevy Equinox Without Factory Towing Package
- Q&A: What Is A Good Wiring Harness For A 2019 Tesla Model 3
- Q&A: Recommended Trailer Wiring Harness for a 2023 Chevy Bolt EV
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.