I have a 2002 Silverado LS 5.3 extended cab. My brake lights stopped working and I've changed the brake light switch and the junction box for the rear lights. Fuses look good but the 2 under the hood give me nothing with a test light. BUT! If I reach down and push the lever for the trailer brake I have brake lights! Got me really scratching my head and don't know what to do next. Any help would be greatly appreciated!

 

You're going to need an electrical schematic to trace the issue.
Try the charm.li website.