Troubleshooting LED Lights Not Working On Trailer
Updated 09/15/2020 | Published 12/22/2015 >
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Question:
Hi, I have converted my boat trailer lights from 12v 21w bulb kit to a 12v led system. I wired it all up using the same colours as previous kit and tested it on my car. None of the led lights are working. Do i need a 50w load resistor to get them to turn on? I have hooked it up to a external battery and works fine but when it is attached to car nothing.
asked by: Nick
Expert Reply:
The first thing I recommend doing is to check that the ground wire for the lights is securely attached to a clean metal surface on the trailer frame. A loose ground wire will keep the lights from working. If the ground attached to the trailer does not give you an adequate ground, you can run the wire up to the ground circuit on the trailer connector.
Next, you want to make sure the wiring on the trailer is wired correctly and wired by function, not just by color.
I recommend using a circuit tester like part # PTW2993 to test the functions of the wiring on your vehicle connector and then make sure the wiring on the trailer connector is wired correctly. I have attached a link to a helpful article about trailer wiring you can check out.
If you still have no luck, you may need resistors for each light, like part # ALEDRST1B or part # ALEDRST2B. One resistor is required for each light.

Ben S.
7/23/2020
I have recently added LED lights to my old boat trailer to include side markers. All the lights work including the side markers. The right tail light is not working, brake I have checked the ground on the tail light and it looks great, bilker etc. The side marker just up from that light works fine so I know its not the ground at the main terminal or the ground at the side marker. Any ideas?



Product Page this Question was Asked From
Combination LED Trailer Tail Light - Submersible - 6 Function - 11 Diodes - Passenger Side
- Trailer Lights
- Tail Lights
- Rear Reflector
- Side Marker
- Side Reflector
- Stop
- Tail
- Turn
- Square
- Surface Mount
- Submersible Lights
- LED Light
- 5L x 5W Inch
- Red
- Optronics
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Jeffrey B.
7/20/2020
The optronics LED drivers side light does not function properly. Had one previously that worked fine. Installed new 4 pin harness thinking there might have been a break somewhere but got same result. The turn signal and brakes will work but not as bright as right side. There is no light on left side or plate light working. Running lights on side work but if you turn truck headlights on they go off. Same results on three trucks, so I doubt that anything is wrong with truck circuits. Keep reading about poor grounds but I am at wits end. Any thoughts?