Car alarms emit high-volume sounds, such as a siren, klaxon, previously recorded verbal warning, the vehicle's horn, or a combination thereof when there is any security threat or when conditions for triggering an alarm are met.
The alarm may also flash some of the vehicle's lights, and some of these alarms also notify the car's owner via a paging system. There is also an option to interrupt and stop various electrical circuits so that the car is disabled and cannot be started.
Car Alarms can be equipped from the factory itself or installed later.
Keyless remote car burglar alarms are generally based on strong cryptography authentication methods, including Radio receiver, Immobilizer, Motion detector and Wireless USB.