Standard Color Code for Wiring Simple 4 Wire Trailer Lighting
Updated 05/31/2026 | Published 08/07/2009 >
Question:
I have had to mess with trailer wiring for years, once or twice a year anyway, and I just cannot keep the color code right, ect white/ground, brn/ running lights, grn/ right turn, yellow left turn? Please help me get it right. thanks
asked by: Gary R
Expert Reply:
You have it right so far, the 4-way connector is just as you have stated. Remember that Yellow has a L in it so that is the left side brake/turn signal and green has a R in it so that is the right side brake/turn signal.
The colors for wiring a 7-way connector are as follows with the 4 colors of the 4-way connector remaining the same.
White-Ground
Brown-Tail/Running Lights
Green-Right Turn/Brake - Remember green has an R in it
Yellow-Left Turn/Brake - Remember yellow has an L in it
Blue-Brake Controller Output
Purple-Auxiliary 12v Power/Reverse Lights/Reverse Lockout For Trailer Brakes
Black 12v Battery Power
I have posted a link to our FAQ wiring page for more detailed clarification.

Y
5/24/2020
I don’t have a white wire coming out of my Chevy 2006 pick up. Red black and blue are the three big wires then ther are five other I want to hook up a flat 4 prong hook up to my trailer which wires do I use my trailer connecter has four colors green Brown white and yellow what goes where!!!!




Steve
7/25/2020
I have two amber and two red side marker lights for a boat trailer. This is an older 1999 trailer. The existing lights had one wire connected and it’s the brown wire (4-pin) 5 wire. The replacement lights have two wires red and black. I currently only have the brown wire exposed. How do I wire brown wire to this light.




Bob O.
8/12/2020
1995 GMC C1500, the OEM trailer harness has all the standard colors plus a lighter green, five total. Can I assume the lighter green is backup lights?


Leo
7/24/2024
Bob, I have this wiring diagram and colors on my 6 way plug (towed vehicle) and recently purchased brake buddy Part#39332 battery maintainer, what location do I attach the red wire that is attached to the brake buddy part 39332, since the black wire will be attached to the positive terminal of the towed vehicle? Thx for your assistance. Leo
Product Page this Question was Asked From
16 Gauge, 4 Conductor Bonded Parallel Wire - Per Foot
- Wiring
- Wire
- Bonded Wire
- 4 Wire
- 16 Gauge
- Deka
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Dennis
4/14/2020
I have a separate wire for brake lights. How does that connect into a 4 pin connector?Thanks for any help