I have a 06 2500 GMC and I noticed the other day when I was getting launched at the ramp that my brake lights in the bed are not working. The third brake like works fine and the brake lights on the trailer work fine but not on the truck. I checked the bulbs and they are fine. The running lights even work. It's driving me crazy need some help.

you have a blown brake light fuse,,under the hood...their are 2 fuse's the one inside the cab id for the 3rd brake light and their are separate brake light fuse's for the trailer..it should read STOP LT or somthing of sort..

Not the issue. I have replaced all fusses even though they looked good. I am going to put a new brake light switch in today hopefully that does the trick.

Doubt it, if the trailer and third are working then the switch is good.

Agree there are separate fuses for truck and trailer stop lights, however there may be a ground problem on the bed, easy to check with a test light

See if the lights are working without the trailer. If not its the truck.

Wannabe

Check the junction block on the frame crossmember behind the spare tire, seep rate plug for each tail light and they do come loose from time to time

Chevy tail light assemblies have small boards in them, I doubt it since it's both of them, but better to know all the possibles and take them one by one. Wiring shorts can really suck.