Troubleshooting Left Side Running Lights Not Working When Brake Lights Activated

Question:

Why does my left side tail lamp go out on my boat trailer when I allly the brakes on

asked by: Al P

Expert Reply:

It sounds like there is a ground issue somewhere on the trailer. A weak ground will typically show itself when there is more draw on a system, such as when you have the running lights on and then need power the brake lights on top of that.

First check to make sure the main ground on the trailer wiring harness is secured to a clean, bare metal surface that is free of any corrosion or debris/paint. If the main ground is good, I recommend checking the ground connection on the left side tail light assembly itself. Depending on the style of light that you have, it may ground through a dedicated ground wire or through its mounting hardware. In either case, you will just want to make sure it is secured to a clean bare metal surface.

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

expert reply by: Chris R