[John Rogers]

Some things to check while you are laying under the dash on your belly looking at the switch are. Fuse #8 which feeds the brake light switch. Make sure it has power and is not open or blown. At the switch, there should be +12 volts with the key on at the black/yellow stripe wire and there are usually two at the hot side. If you have power to the switch, cycle it to see if you get power at the outlet side, +12 volts when pedal is depressed. If all of that is okay, you can check the voltage to the light bulb socket. You can do this by pulling the bulb and checking center connector to ground with brake pedal pushed. Finally you can check the ground for all the lights which are the brown wires and I forget where they run on a '71 but on my '73 they went to a small stud on the inner trunk wall near the lights.

I would suggest using a known good volt meter and check it against the battery to make sure it reads right. I would surely hope you have one, if not, NOW is the time to buy one. It also helps to lay 4 or 5 pillows on the floor to lay on as it helps keep your stomach and chest from getting sore!