Seat belt

[Gregsenne]

Couple of questions about my seatbelts in my 1986 GMC High Sierra 1/2 Ton 4wd. It is a project truck I am building, never had it running yet... and it doesn't drive yet...

There is a black wire that runs from under the dash to the driver side seatbelt mechanism (the part on the floor that coils up the belt). There is no wire that goes to the passenger side one. What does this wire do?

There is no wire going to the seatbelt latch. Do I have a wire for latched seatbelt that turns off the seatbelt light? Or does the light just come on when you start for a fixed period of time then shut off regardless if you are latched in or not?

Right now my seatbelt is loose. It doesn't click into place in any position even if you pull it all the way out. How does the seatbelt lock in place in case of an accident? (Because if it doesn't lock in place, it doesn't seem as if the seatbelt is actually serving any purpose)