Troubleshooting 3rd Brake Light on Trailer that Flashes with Truck Off

Updated 11/28/2017 | Published 11/27/2017

Question:

the 3rd brake light flashes on my 09 adams horse trailer a single flash approx. every 20 seconds when the truck is off and just sitting there they are hooked up. it is a very fast flash and only once LED Light.

asked by: Dean

Expert Reply:

It sounds like it's possible that the brake light wire from your 3rd brake light might be coming into contact with the electric brake wire on the trailer. The brake controller on your truck will send an intermentent, extremely small amount of power back to the trailer brakes to check for a connection, and if this wire is connected in anyway to the brake light wire, the power might be enough to activate the light. This is especially true for LED lights, as they require such little power to turn on.

I recommend tracing the wiring back from the 3rd brake light to see if there are any exposed areas that might be touching nearby wires, simply fixing as needed.

If this does not resolve the issue, please let me know and I will be happy to look into this further.

expert reply by: Chris R