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.