Seat Belt Interupt Options

[Rob-O]

My car is a ‘74 with the seat belt interrupt circuit. All the years I’ve had it I’ve just had the system bypassed with the yellow wires connected together. But after restoring most of my interior (including seats and the ‘Fasten Seat Belt’ light. I thought it would be neat to reinstall the relay (while keeping the yellow wires spliced together. So I picked up a relay from Mark Heard (thanks Mark!) and installed it. A perhaps important side note is that when I had my seats redone by Autobahn Interiors, they replaced the seat bottom foam and did reinstall the seat bottom sensors. Now I have the following issues. The light doesn’t come on when someone is in the drivers seat, whether the seat belt is connected or not. On the passenger side the light comes on whe NOBODY is in the seat but turns off when I connect the belt. In looking at the diagram I suspect the seat bottom sensors. They may not have been put in the ideal place when the seat cushions were re-foamed. Or something might be wrong with the sensors themselves. My question is, exactly how do the seat bottom sensors work?

Sorry I’m advance for the long post but wanted to give as much info as possible. Shameless interior pic for good measure.