I have an 89 s5 and the door catch switch has gone bad. the dealership said that it is no longer available. i am going to take it apart and try to fix it but i am not sure if it is in the handle or in the latch that locks to the striker. i am tired of the seatbelt light being on and aparently because it is not part of the motor or rail it is not under warrenty. anybody have any ideas.

 

You could disable the light, but if you want to fix it properly I'm not sure. I don't know how the track belts are constructed.

 

I'm confuzzled about what the "door catch switch" is, exactly.
I thought the seat belt computer knew the door was open by using the same simple switch that operates the dome light...does your dome light come on when the door is open?

 

The dome light does work. But the seatbelt light is still on, and the door catch switch is what i was told was wrong at the dealership. Im not sure how all of it is wired either.

 

Try this:

At the base of the seat belt receiver is a two wire connector, when you plug in the lapbelt it completes the circuit and tells the system the belt is fastened.
Unplug this connector and bridge the two wires in the chassis side of the harness.
The warning lamp should go out.
If so, the problem is right there at the receiver belt switch.

If not, you'll just have to follow the tree and see what else inputs into the circuit.