Section 28085 Of Article 13. Theft Alarm System From California Vehicle Code >> Division 12. >> Chapter 5. >> Article 13.

. 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.