No brake lights. Everything works but the brake lights. all fuses good need direction please. Going to check junction block where all the connectors are at by the back bumper.

all connection good at back of truck

brake light switch above the brake peddle could be the culprit.
Maybe if your lucky , it just got unplugged, check the wires going to it.
Charlie

Couldn't be that I don't think because the third brake light works.

When you say all fuses are good ,did you check voltages on both sides of all fuses?There are some under the hood.

Do the turn signals work?They use the same wires as the brake lights.

The center brake light doesn't run through the turn signal switch,but the rear brake lights do.

Big, I had the same problem that you are having. I know you checked the rear harness, but I will tell you what mine ended up being. It was the harness in the rear. If you are looking at the harness, the connector on the left side was not making good contact. It would work for a short time and then it would not work(had 3rd brake light on the cab,but neither of the tail lights). I had to take a wire tie and pull the connector to the side for it to make consistent contact.

If yours is bad, the replacement 4 gang terminal block is part# 15304995 (about $20). I had to wiggle that left connector back and forth to determine the problem.

When you say all fuses are good ,did you check voltages on both sides of all fuses?There are some under the hood.

Do the turn signals work?They use the same wires as the brake lights.

The center brake light doesn't run through the turn signal switch,but the rear brake lights do.

Turn signals worked. they are different bulbs on the 03. Found out also the third brake light is a dedicated circiut so it is a saftey so even with out fuses and tail lights that one will ussally always work unless it has it own problem. come to find out I double checked all my fuses pulled them out and reinstalled them and it was a fuse makes me feel stupid but it was dark out side and it was one in the side dash fuse panel. Thanks for the help though.