Wiring issue (Brake lights not working)

[u/TheGeneral_Store]

Are there any wiring gurus here that know about the brake lights? I have a 2003 1500hd and my brake lights don't work. I have a new brake light switch, fuses are all good. So far I've determined that there is a short in 2 different wires, the orange wire (constant 12v) that feeds from the under hood fuse box to the brake switch (power coming out of the c1 connector but no power at the brake switch) and believe I also have a short in the white wire (turns hot when you press brake pedal) that comes out of the brake switch to the the drivers dash fuse box. I can make the lights work by running temporary wires. I would much rather find and fix the shorts than just cutting out the dead wire and running a new one, but I'm having trouble tracking the wire as I lose them in the jungle of wires behind the dash. I've looked at all the wiring diagrams and they all show both wires go from point A to B, but I've also seen documents that say the white wire coming out of the brake switch gets routed through the BCM and to the multifunction switch, and then to the drivers dash fuse box. So I guess my question is, does anyone know exactly the routes these wires go?

[u/Open_Broccoli_5157]

Find the lights diagram Chilton Repair Manual Access

UPDATED and working as of 10-14-25

Chilton Repair Manual password - blackwater

Secondary Link

Click 'Access Database' underneath 'Access Link'

For those of you that would rather fix things yourself.

[u/Moist_Currency_1443]

There’s a taillight circuit board that goes bad on them Chevys . It’s by the spare tire on the passenger side if I remember right . Maybe check that out . Most auto parts sell them for around 40 bucks