How to Determine Wire Functions on Trailer with Mixed Wire Colors
Updated 02/03/2026 | Published 07/24/2024
Question:
I’m wiring tail lights in my camper where the wires have been crazy. On the left license plate side There are 2 green, 2 black and a red coming from the camper And standard black red white on the tail lights Where do they go?
asked by: Jerica
Expert Reply:
Hey Jerica, thanks for reaching out!
It sounds like someone else has done some wiring on your camper as well and used none-standard wire colors for upgrades/repairs. The best way to figure out what function each of those wires carry is to apply 12V power to each one individually to see what it activates - aside from that there isn't a way to verify what is what unless that really is OEM wiring and the manufacture has a diagram listing those wire colors.
As for your tail lights, it sounds like they have wiring similar to the Optronics Fleet LED Trailer Tail Lights w/ Grommets # TLL12RK which has the following functions for those various wire colors:
White - Ground
Black - Tail light
Red - Turn signal
Product Page this Question was Asked From
Optronics Fleet LED Trailer Tail Lights w/ Grommets - Stop,Turn,Tail - Submersible - Oval - Qty 2
- Trailer Lights
- Tail Lights
- Brake/Tail/Turn
- Oval
- Recessed Mount
- Submersible Lights
- LED Light
- 6-1/2L x 2W Inch
- Red
- Optronics
more information >
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Lazer S.
2/3/2026
Hey Jerica, what ended up happening when you tested each wire on your camper to see which function it powered? Knowing how that worked out could really help others sorting through mixed wire colors on their tail lights.