The brakelights on my 1967 Firebird don't work. I have check the brake light switch, it works. If I hook the white wire to the fuse block the left brake lights work. When I hook the orange and white wires to the brake light switch, the orange wire has 12 volts, but when I push the brake pedal the voltge goes to zero. I thing this is a ground issue, but don't know where to start. I have a new light switch coming, and have already replaced the turn signal switch.
Your switch should allow energy to pass through it when the pedal is pressed. So it sounds like it's not wroking properly. Replacing it should do it. If you continue to have problems after the swith is operational, then look for ground issues starting at the bulb sockets and working your way back to the switch.
You might have a parasite voltage drop. If you have a multimeter you can find the problem in about 10 minutes. Parasite in this case means someone else consumes the voltage or may be an open circuit. Remove the bulb depress brake pedal and check voltage at the socket. If Nothing, take the négative lead and connect it to a know good ground, Recheck voltage, if you have no reading connect one end to the ground of the socketand the other one to the positive of the batterie if you have 12 then start to go towards the center of the carpedal switch, flasher unit etc. also check the connector in the trunk. Fast explination if you have any question you can pm.
