The car is a 1996 Acura Integra. I wanted to replace the factory head
unit. I heard somewhere that doing this would kill my keyless entry.
I accepted this fact and went ahead with the head unit removal. At
this moment, the factory head unit is out of the car and the new one
has not yet been installed. The keyless entry still works!

This seems to contradict everything I have read. Does anyone know how
it is still working?