s6 radio in a 91 200 TQ

[rich <rich@smu.edu>]

I recently re-installed the Audi bose radio that some poor clueless
person had taken out of the car.  Anyway
the radio I got was out of a S6.  In terms of functionality,
everything works but as I recall the S6 radio had some sort
of theft deterrent that would cause the red led on the front
of the radio to flash.  Could someone tell me what I need to 
hook up where to cause the red led to flash and thereby enabling
the theft deterrent feature?

thanks

rich andrews sr.