28085.  Any motor vehicle may be equipped with a theft alarm system
which flashes the lights of the vehicle, or sounds an audible signal,
or both, and which operates as follows:
   (a) The system may flash any of the lights required or permitted
on the vehicle.
   (b) The system may sound an audible signal.
   (c) No vehicle shall be equipped with a theft alarm system which
emits the sound of a siren.