Trailer lights not working
 

I have a 99 Jimmy 4WD. I have a trailer hooked up right now and have a strange problem. When I turn the headlights on, the trailer lights come on, but the brake lights and signals don't work. I have to haul a bike this afternoon, anyone know what would be causing this?

RE: Trailer lights not working
 

Are you using a 4pin plug or a 6/7 pin plug? I am going to assume that you have the 4 pin plug as you didn't mention anything about reverse lights or the other features present in a 6/7 pin plug.

Here are a few illustrations of the wiring so you can probe at the connector to see if you have what you need to have.
http://www.accessconnect.com/images/...y%20wiring.jpg
As you can see, the green wire is your right stop & turn. Yellow is your left stop & turn. Brown is your tail, marker, license lights. And Black is the trailer ground.

For the brakes, the green and yellow wires should have +12V constant to them. For the right/left turn, the green/yellow (respectively) wire should have intermittent +12V corresponding to the blinking of the turn signal. Whenever your marker lights are on, the brown wire should have +12V constant.

Since you have the marker lights, your ground should be ok.

Hope this helps!