Troubleshooting LED Lights on 2008 Shadow Horse Trailer

Updated 04/18/2020 | Published 03/19/2017

Question:

2008 Shadow horse trailer. All lights are LED. All turn signals and brake lights function properly. The right rear marker light and right-rear turn signal light will not light up in running light mode.

asked by: Paul K

Expert Reply:

Since most of your trailer lights are functioning I would check the two subject lights' mounting and wiring for the cause for the problem. If the light uses a mounting stud or mounting hardware to establish the ground, like # MCL95AB, then you can try sanding/cleaning the mating surfaces to remove any corrosion, dirt or trapped moisture that could be interfering with the electrical connection. Also inspect the wiring for signs of damage from road debris or hungry critters.

Once you have access to those lights' wiring you can test them directly with 12V battery power to see if they still function. If they do work when directly powered then you know the problem is in the ground or wiring; if they do not work even when directly powered then the LEDs elements may have gone bad and need to be replaced.

I linked our main page for all LED-type trailer lighting and you can click on the filters on the page to choose the shape and size of the lights you need.

expert reply by: Adam R

Vickig

4/17/2020

Paul K, I have the same problem with my 2006 Shadow. I am installing new lights from etrailer and the same problem occurs. Did you ever get yours to work right?

Chris R.

4/17/2020

I'm not sure we heard back from Paul but I can certainly try to help with your lighting issues. Is it the running lights on just one side like above, or is the problem on both sides of your trailer? In either case, make sure those new lights are securely grounded and unless you've already tested this, also keep in mind that the issue could actually be on the tow vehicle. Verify that you're getting power at the running lights pin on the vehicle's connector with a circuit tester - if not, check for a blown fuse under the hood. Let me know what you find and we'll keep troubleshooting.

Vickig

4/17/2020

Here’s my problem, maybe not the same, but the same trailer. I ordered 2 Optronics LED Trailer Tail Light - Stop, Turn, Tail - Submersible - 10 Diode - Oval - Clear Lens Item # STL88RCB to replace OE because some of the diodes had failed AND the left turn signal didn’t work when the car headlights were on. Checking function after installing new lights I got this: car headlights off, both right and left brake and turn signals work. Headlights on, both tail lights on, but no change for braking or turn signals. New lights are securely grounded. Maybe tow vehicle is the problem, it’s a Cayenne and those Porsche boys looked confused when I told them I wanted to pull a horse trailer!I will check the things you mentioned when I go to barn tomorrow. Thanks!

Chris R.

4/18/2020

That sounds good. The more you describe the issue the more it sounds like a possible weak ground somewhere. I know you mentioned that the new lights are securely grounded - but most of the time when you have problems only when the running lights circuit is active (which requires more power), a weak ground somewhere is the culprit. Ensure the main harness ground on the trailer also still has a good connection to clean, bare metal.