Wiring Guide for Installing Lights on Trailer with 5 Wires
Updated 12/27/2018 | Published 12/24/2018
Products Featured in This Question
Question:
I have 5 wires from my trailer but only 4 on my new lights how do I connect them up
asked by: MARCIN C
Expert Reply:
A trailer can have either 4-pole or 5-pole connectors and the number of actual wires can vary too.
For instance, the part you referenced # 16-4B-1, is 4-pole wiring like what is included in a part like # W787274 which is a trailer-side 4-pole setup that carries stop, turn and tail light signals. There are also 5-pole connectors like # HM47910 that add one additional circuit that can be used for trailer brakes or another function.
Then there are also wishbone style harnesses that have a second wire connected to the pin for the running light circuit. The second wire just simplifies hookup for both sides of the trailer. There are 4-pole wishbone harnesses like # A35W42B and 5-pole wishbone harnesses like # A40W5B, both of which have the second BROWN wire on the running light circuit's pin. The linked photo shows a 4-pole wishbone connector with two brown running light wires.
The best way to know what each wire on the trailer does is to test it by applying power from the vehicle battery or a well-charged spare if you have one. This will let you know how to connect each wire to the lights you wish to install. The linked article shows the way each type of trailer connector has its various circuits arranged.
If the linked article does not give you the information you need please tell me more about your lights and perhaps include a photo of your trailer wiring connector.
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
- Search Results: 13640
- Search Results: bearing buddies
- Search Results: bearing buddy 2441
- Search Results: hdpb330301
- Search Results: trailer door hinges accessories and parts
- Search Results: trailer breakaway kit
- Search Results: 9~123
- Shop: Curt Trailer Hitch Receiver - Custom Fit - Class III - 2"
- Shop: Trailer Hitch
- Shop: Bearing Buddy Bearing Protectors - Model 2441 - Chrome Plated (Pair)
- Shop: Bearing Buddy Bearing Protectors - Model 1980A-SS w/ Auto Check - Stainless Steel (Pair)
- Shop: DeeZee Specialty Series Truck Bed Transfer Tank - Rectangle - Aluminum - 108 Gallon - Silver
- Shop: Trimax Receiver Lock for 2" and 2-1/2" Hitches - 3-1/2" Span - Stainless Steel
- Shop: Trimax Receiver Lock for 2" and 2-1/2" Hitches - 3-1/2" Span - Black
- Shop: Demco Recon Gooseneck-to-5th Wheel Trailer Hitch Adapter for Recessed Ball on Aluminum Beds - 21K
- Q&A: Recommended Brake Controller for 2025 Toyota 4Runner
- Shop: Brake Controller
- Q&A: What is the Difference Between a Class II and a Class III Hitch?
- Shop: Trailer Wiring
- Article: Brake Controller 7- and 4-Way Installation Kit (ETBC7)
- Article: Trailer Wiring Diagrams
- Q&A: What is the Difference Between a 4-Way and 7-Way Trailer Connector
- Video: B&W Companion OEM 5th Wheel Hitch Manufacturer Breakdown
- Article: How to Choose the Right Trailer Hitch Class
- Shop: Suspension Enhancement
- Q&A: What Is An OEM Prep Package And How Do I Know If I Have It
- Article: How to Measure for Trailer Hitch Drop
- Video: Curt T-Connector Vehicle Wiring Harness Review C56040
- Q&A: Does Truck with 6-1/2 ft bed Have to Use Slider Hitch for Turning Clearance with Fifth Wheel Hitch
- Video: How to Choose a Trailer Brake Controller
on Wiring
