Troubleshooting Trailer Lights Not Functioning When Headlights are On

Updated 09/07/2011 | Published 09/05/2011

Question:

I have a 1995 Chevy PU with the 3 separate factory installed tail lights. My old trailer lights, grounded to the mounting bolts. without separate ground wire, worked with the existing wiring harness. two wires to each rear light and a ground to the trailer.. I installed Blazer lights, which come equiped with two wires + ground wire. I grounded each to clean bolts and installed the wiring exactly as the old trailer tail lights.G and B right Y and B left Problem: Without the headlights on everything works, the turn indicaters and the brake lights. With the head lights on, the tail lights are on but when I step on the brake, all of the lights go off. If the headlights are on and I turn on a turn signal both tail lights just flash. Any advice on what is wrong would be helpful.

asked by: Nck N

Expert Reply:

It sounds like there is too much amperage being drawn on your trailer when the headlights are on and it is too much for the trailer so everything shuts off. This could be because of a bad ground somewhere.

First thing I would do is check the grounds on the trailer for any loose wiring and corrosion and fix as necessary. If the grounds are good you might need to convert your trailer lights to LED lights so as to minimize the draw on the trailer light circuits.

LED lights draw a fraction of what a incandescent bulbs draw and should work well on your trailer. I attached a link to a page that has our LED light kits for trailers for you to check out.

expert reply by: Jameson C