Troubleshooting LED Lights Not Working On Trailer

Question

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

0

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.

expert reply by: Jeffrey L

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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?

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Chris R.

7/26/2020

I'm a little unclear on what exactly isn't working. Is it JUST the brake signal or the brake AND turn signal on that side?

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Ben S.

7/28/2020

@ChrisR it is the right side brake and turn signal that aren’t working. It’s strange as there is current to the side marker which is working. I will dbl check all the grounds again.

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Montell W.

9/13/2020

@ChrisR , iam having just about the same problem both LED lights come on , but will not blink for either sides & no flashing hazard light's - but brake light's. Very good ground , what am I doing wrong " please help " , its a boat trailer & the fishing season is coming to a close

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See All (4) Replies to Ben S. ∨

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?

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Chris R.

7/26/2020

I hate to same the same thing you've already heard, but this does sound like something a weak ground would cause. I'm not certain how your Optronics assemblies ground (whether it's through a dedicated wire or through its mounting hardware) but either way, make sure it's attached to a CLEAN, bare piece of metal that's free of any debris or corrosion. It may even be worth it to just remove the ground or light, sand down that surface really good, and reattach.

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Jeffrey B.

7/26/2020

@ChrisR Thanks Chris R. Ya know why they give you 3" of wire and tell you to affix it to the bolts that hold the light on, is now beyond me. Spliced in enough wire to reach trailer frame, drilled hole, wire wheeled down to bare metal and you are right! Everything works fine with proper grounds.

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Jeffrey B.

7/26/2020

@ChrisR Thanks Chris R. Ya know why they give you 3" of wire and tell you to affix it to the bolts that hold the light on, is now beyond me. Spliced in enough wire to reach trailer frame, drilled hole, wire wheeled down to bare metal and you are right! Everything works fine with proper grounds.

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Answer 1

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…

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Answer 2

It sounds as though there is an issue within the one left-side LED light assembly itself. Since LEDs draw so little power it is unlikely that there is an issue with overloading the trailer wiring. If only 7 of the 10 LED elements are now working it…

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Answer 3

The problem you are experiencing sounds like a ground issue and/or short circuit. 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…

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Answer 4

You may not even need load resistors to switch to LED lights. The best thing to do is to try the lights without load resistors first. No need to purchase something you may not need until you know need it. Load resistors such as #DI34ZR dissipate…

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Answer 5

I have a solution for you but there isn't just a replacement converter section for the Elixir ELX-45. You're going to need to replace the entire panel with the Progressive Dynamics Mighty Mini AC/DC Panel and Converter/Smart Charger…

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Answer 6

Either way is correct. It depends on if you want to keep the semi-style 7-Way (if you need to tow that type of trailer) or if you will never be towing a semi-trailer. If you need to keep the 7-Way semi active on the truck, then you would need to make…

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Answer 7

You will first want to check the fuses on your tow vehicle. Some vehicles could have fuses for operating the turn signals and brake lights of a towing package. You will want to check if they are installed and working properly. The next thing is to…

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Answer 8

It could be a tow package fuse on the vehicle. Use the owners manual to find the locations of fuses/relays related to the tow package wiring to check them and replace as needed. If the issue is not a fuse or relay then you can test the vehicle side…

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Answer 9

The most likely cause for the incorrect behavior of your trailer lights, where activating one turn signal causes all trailer lights to blink, is an insufficient ground (or a short to ground) on either the vehicle or the trailer. Since you re-wired…

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Answer 10

The most likely cause for the turn signals not to work when the running lights are on with your trailer is a bad or weak ground. It's very possible that a weak ground connection can be just strong enough to allow sufficient current for some…

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Answer 11

If you tested the LEDs and they work when they have power and ground the problem has to be the wiring of the trailer. Since previous lights worked there it would seem that the problem may be somehow ground related. Some assemblies ground through…

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Answer 12

Load resistors such as #DI34ZR just create more current draw on a circuit. The constant draw should be compatible with the CANBUS system on your Mercedes but it is possible that the vehicle computer may consider it a short and throw a warning. They…

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Troubleshooting LED Lights Not Working On Trailer

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