NEED HELP, Problem with trailer wiring.

I have a 2003 Z-71 with the factory tow package. I pull a trailer regularly in the summer months usually 2-3 times a month. I hooked my trailer up the other day and I noticed my passenger side turn signal & brake light was not working on the trailer. I changed bulbs and still nothing. I then hooked it up to another truck and everything worked fine. I used the same 7-6 adapter on both trucks. That only leave my truck to have the problem. Any body have any ideals. I checked the plug and it is getting a tight connection. Unplugged the harness in the rear and replugged it everything aligned and connected with ease. I am out of ideals anyone have any ideal I would really appreciate the help.

this my sound strange, but make sure you have a heavy duty turn and hazard relays.

check your fuses and also use a test light to check for power at the trailer plug with the lights on.

Thanks guys, I checked the plug and was not getting power for the passenger side trailer turn signal/brake wire. Ended up being a 10amp fuse under the dash. Wish I would have thought of the fuses prior to replacing the entire brake light assembly.

In my 2005 Astro van, I believe there is one fuse for brake lights and one fuse for turn signals. If my wiring is all right, is there any way the fuses could be responsible for just the passenger brake and turn lights to not be working on the trailer only?

Tazb, pull the cover off your fuse box. On the back should be a diagram of all the fuses. Double check to see how you fuses are set up. I would think that chevrolet would wire all there vehicles the same, but who knows. You may need to also check the fuse box under the hood. It will also have a diagram on the back side of it. If you are correct and there is just the one fuse, I would hook your van upto a different trailer to see if you get the same results. Good chance it could be in the plug or wires on the trailer.