Dashboard Seat Belt Warning Lights

My 1991 Lamborghini Diablo is an USA model. It came with those passive automatic seat belts that move automatically on a runner. Most if not all owners have since removed the belt and just manually connect and disconnect the lap belt and shoulder belt. Mine has been removed also. Back in the day, the USA government required this, so Lamborghini had to accommodate. The Canadian version of the 1991 Lamborghini Diablo model year did not have automatic seat belts, just a standard three-point belt. Much better in my opinion. I am thinking of installing these and removing the runners.

Right now when I get in the car, I put the lap belt on and then the shoulder belt. I start the car. I notice that the seat belt warning light for the passenger side is on, flashing for about 60 seconds and then it goes out.

That seems odd to me, since the passenger seat is empty. I would think there should be no light on at all for the passenger side?

Maybe user Sledge4.2 (Geno) could comment on this.

Thanks in advance.....Ron