Why Does 4-Pin Trailer Wiring Have 5 Wires
Updated 02/16/2024 | Published 06/19/2019
Products Featured in This Question
Question:
Please help! I have a 4 pin with 5 wires, W-R-B-Y-G. I have two trailer lights to wire to... Left: R-Y-B Right: R-G-B I know the White from 4-pin is the ground. But the G/B wire from the pin and R/Y wire from the pin are confusing me. If I wire the R/Y on the left to their respective colors, then I have the Brown left alone. Where as, if I wire the G/B on the right, I am left with the Red. Im at a loss. See attached photos below. Thanks!
asked by: Paul M
Expert Reply:
Your 4-pin/5-wire wiring harness is what is called a "wishbone" type which simply means that there are two separate running light wires, one brown and one pink. This allows a separate running light wire for each side of the trailer which saves you having to run a jumper wire from one side of the trailer to the other. We offer lots of wiring items just like this, such as # A35W42B, # A20WB and # A10-4225VP, which happen to use two brown wires instead of one brown and one pink.
The functions of the 5 wires is as follows: WHITE is ground (as you stated); PINK and BROWN are for running lights; YELLOW is for LEFT stop/turn; and GREEN is for RIGHT stop/turn.
Your trailer lights may use wire colors that do not match these so this is why you always want to wire by function rather than by wire color. The lights may be labeled to tell you which wire handles what function but you can always test this with a 12V battery. You can also refer to the linked article on trailer wiring which has lots of detailed information that will help you wire the lights.
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
more information >
Featured Help Information
Miscellaneous Media
Continue Researching
- Q&A: Wiring New 4-Way Connector on Trailer with 5 Wires
- Shop: B&W Patriot 5th Wheel Trailer Hitch w/ Slider for Dodge Ram - Dual Jaw - 18,000 lbs
- Article: Trailer Wiring Diagrams
- Search Results: rubber grommets
- Shop: Trailer Wiring
- Search Results: rv vents and fans
- Search Results: trailer side vents
- Shop: B&W 5th Wheel to Gooseneck Pin Box - Lippert 1621/1621HD - 25K GTW - 4.5K TW
- Search Results: sendel
- Search Results: sendel trailer tires and wheels
- Search Results: rubber end caps
- Shop: 35 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 42" Ground
- Search Results: sidewall vent
- Video: Review of TowSmart Trailer Wiring - Trailer Connectors - TS68QR
- Shop: Dragon's Eye LED Clearance or Side Marker Light - Weatherproof - Oval - 2 Diodes - Amber LEDs
- Shop: Brake Controller
- Shop: TowSmart 4-Way Flat Connector Rapid Repair Trailer Wiring Kit
- Article: Wiring Trailer Lights with a 4-Way Plug (It's Easier Than You Think)
- Shop: Triangle 215/75R17.5 Radial Tire w/ 17-1/2" Solid Wheel - Offset - 8 on 6-1/2 - LR H
- Shop: 20 Ft 4-Way Trailer Wiring Harness - Wishbone Style - 30" Ground
- Q&A: 4-Way Trailer Connector that has 5 Wires
- Shop: Fifth Wheel Hitch
- Q&A: Instructions For Wiring Furrion Air Conditioning Unit with New Thermostat
- Q&A: Wiring Diagram for Softstart on Furrion Chill RV AC Unit
- Q&A: Wiring Diagram for Furrion Chill
- Video: Furrion Chill RV Air Conditioners Coleman Adapter Wiring Kit Review
- Shop: Trailer Hitch
- Q&A: Lift Kit Solution to Allow Fifth Wheel Trailer to Sit More Level When Towed
- Q&A: What is Normal Temperature Rating for Trailer Hubs
- Article: Wiring Trailer Lights with a 5-Way Plug (It's Easier Than You Think)
on Wiring
Tracy W.
2/14/2024
Thank you so much for your expert advice. You have helped me save hours trying to figure out this 5 into 4 wire problem. Your explanation is so easy to understand too. Thank u, thank you. Thank you!