probably what Mopardude said.
in the engine compartment, do you have a metal box with a large red button on the drivers side fender?
get a factory service manual so you can see how things are wired. I'm thinking there was a good thread on how to bypass it and cut in the clear.
when I got my 74', the previous owner had jumpered the wires under the seat to bypass the seat belt connected sensor. someday i'll re-wire the car and it will all be gone
good luck
chuck