Trailer Lights Not Lighting Up Properly on Harbor Freight Trailer
Question:
Hi, I have a haulmaster 4 way wiring harness from Harbor Freight and 2 seperate lights. One is from Harbor Freight and is submersible and the other is from West Marine and is also submersible. The left light HF has a yellow and brown wire and white wire coming out of it and the right light WM has a green and a brown wire coming out of it. The wiring harness has 5 wires, white, brown and red from 2nd port, yellow, and green. I have attached ground up front by coupler and ran the rest of the wires all the way to the back of the trailer in a flexible split loom. The white wire initially ran all the way to the rear with the other wires but I cut it and attached it by the coupler instead. I attached green and brown to the right light and red to brown and yellow to yellow on left light. I attached the red to the brown because the yellow and red wires were together and it seemed like they should run that way. Finally got everything hooked up and grounded the left light to the frame. Turned on truck lights and there are no running lights showing on the trailer. When I put on my right turn signal both lights flash dimly. When I put on left turn signal the left light flashes bright with no light on right. Any idea how I can isolate the problem here? Not 100 sure about the red wire connecting to brown, but it seemed non sensical to have to run brown all the way to right light and run a jumper to left light. I can send some pictures if needed. Thanks in advance!
asked by: Scott
Helpful Expert Reply:
It sounds like the wiring harness you have is what is called a wishbone harness. These will have 2 wires that connect to the single running light pin, so you don't have to run a jumper wire from one side of the trailer to the other.
It also sounds like you have everything hooked up correctly. Yellow is usually left turn and brake lights, green is usually right turn and brake lights, brown is usually running lights, and white is the ground. You can test this by connecting the trailer to the truck and testing the wiring on the trailer side using a circuit tester such as # PTW2993 or a meter if you have one. If the wire colors/functions are different you will be able to identify which wire does what and attach it to the lights accordingly.
You could also have a ground issue. This sounds like a ground issue. Ground problems normally show up when there is more draw on a system such as when you have the running lights on and then use another function like a turn signal or brake light but can show up any time.
Make sure that the vehicle side and trailer side connectors are clean and free of corrosion inside and out. The main connector grounds should be attached to clean and corrosion free bare metal surfaces.
The light grounds should also be attached to clean and corrosion free bare metal surfaces. If there is anything between a light ground and the metal trailer frame or if the trailer has an aluminum frame, tilt bed, or folding tongue, any of these things can interrupt the ground. Running jumper wires from the light grounds to the main trailer connector ground can help. I have also included some additional links that will help.
Products Referenced in This Question
Product Page this Question was Asked From
Submersible, Under 80" Trailer Light Kit with 25' Wiring Harness
- Trailer Lights
- Tail Lights
- License Plate
- Rear Reflector
- Side Marker
- Side Reflector
- Stop/Turn/Tail
- Square
- Kit
- Surface Mount
- Submersible Lights
- Incandescent Light
- 5L x 4-1/2W Inch
- Red and Amber
- Optronics
more information >
Continue Researching
- Shop: Trailer Wiring
- Shop: T-One Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
- Shop: Curt T-Connector Vehicle Wiring Harness with 4-Pole Flat Trailer Connector
- Shop: Malone Crossbar Conversion Kit for Standard Utility Trailer
- Shop: Trailer Hitch
- Article: Trailer Wiring Diagrams
- Shop: Bunk Kit for Malone Trailers - 1 Kayak
- Video: Review of Malone Trailers - Crossbar Conversion Kit - MPG475
- Article: Troubleshooting 4 and 5-Way Wiring Installations
- Q&A: Malone Crossbar Kit For 6'x8' Utility Trailer
- Shop: Optronics LED Clearance or Side Marker Light w/ Reflex Reflector - 6 Diodes - Square - Amber Lens
- Q&A: Troubleshooting Trailer Lighting Where Only One Running Light Works
- Shop: 1-7/8" Hitch Ball - 3/4" Diameter x 1-9/16" Long Shank - Chrome - 2,000 lbs
- Shop: etrailer Hitch Pin Alignment Collar for Hitch Accessories - 2" Hitches
- Search Results: trailer hitch
- Search Results: transmission coolers
- Shop: Transmission Cooler
- Q&A: Least Visible Trailer Hitch Recommendation for 2009 Toyota Corolla
- Video: Curt Trailer Hitch Installation - 2019 Toyota Prius
- Q&A: Is There Difference Between Optronics Taillight Kits TL5RK and TL29BK
- Q&A: Recommended Wiring And Trailer Light Kit For Harbor Freight Trailer
- Q&A: Best 4.80-12 Trailer Tires For Highway Speed
- Video: Optronics Submersible Trailer Light Kit Installation
- Q&A: Replacement Brake Assemblies and Hubs for 1960 Airstream Trailer
- Video: Performance Tool Hook Probe Circuit Tester Review
- Search Results: 4 pin extension
- Video: Trailer Wiring Harness Installation - 2015 Subaru Forester
- Search Results: hadco
- Video: Optronics LED Trailer License-Plate Light with Mounting Bracket Review
- Article: How to Choose the Right Trailer Hitch Class
Scott S.
4/1/2024
Ironically I have the exact same issue with my haul master Harbor freight trailer lights right now. Tried putting a new wire system on the 20 year old HM trailer and the light symptoms are as Scott described above. I even disconnected the white ground thinking the lights wouldn’t work and they’re still on with incorrect lighting. I feel like I have to buy a whole other wire bundle.