How does car anti-theft alarm work?
An anti-theft car alarm system is a type of security device that helps take measures to protect cars when it detects signs of a car being broken into.
Car anti-theft systems usually protect the car by sounding an alarm with a horn and lights, preventing the car from starting, sending notifications to the car owner, etc.
Depending on the structure and settings, each anti-theft system will have different anti-theft functions.
Structure of anti-theft system on cars
There are many types of car anti-theft systems. Each type has different structures and corresponding features. However, most types of anti-theft alarms today have the following main components:
Controller (anti-theft ECU): Receives signals from the switch and sensor system. If it detects that the vehicle has been broken into, it will transmit a signal to activate the alarm system.
Alarm devices include: sirens, car horns, headlights and taillights. These devices will help alert when the car is being broken into.
The switch system includes: car door switch, hood switch, luggage compartment door switch, electric lock switch and door lock assembly... These switches help detect the open/close status, then transmit the signal to the anti-theft ECU.
Sensor system: Intrusion detection sensor sends wave signals into the cabin to detect movement in the cabin and send signals to the anti-theft ECU.
How the anti-theft system works on cars
The anti-theft system on cars has 4 states:
Inactive state: The system is not working at this time, so it will not detect if there is a break-in.
Ready to work state: This is the delay time until the system reaches the alarm state. In this state, the system also cannot detect if there is a break-in.
Working status: At this time the anti-theft system is active and can detect if there is a break-in.
Alarm status: If any door or hood is opened with unusual force, the battery terminal is removed, the glass door is broken, the cabin has unusual movement... the switch and sensor system will transmit a signal to the anti-theft ECU.
After processing, the anti-theft ECU will command the alarm system to be activated. At this time, the alarm siren sounds, the car lights flash continuously. In some systems, the ECU also prevents the car from starting.
What is Immobilizer Anti-Theft System?
The Immobilizer Anti-Theft System is a system that prevents the vehicle from starting the engine when the ID code transmitted from the key does not match the pre-registered ID code in the ICM (Immobilizer Control Module). This is a system that significantly reduces the rate of car theft in addition to anti-theft warning systems with horns and lights.
Immobilizer anti-theft system structure
Satellite Transmitter and Remote Transmitter: This part is integrated into the vehicle's ID key. This is where the vehicle's encryption data is stored. If there is no signal from this part, the ECU will disable the vehicle.
Anti-start system remote control: This part helps receive and transmit signals from the satellite transducer to the ECU.
MICU (with integrated immobilizer) and ECM/PCM: This part helps receive and process signals transmitted by the remote control of the anti-start system.
Indicator light: The indicator light helps to notify the operating status of the system. If a failure occurs, the ECU will send a warning signal to the user through this indicator light.
How the Immobilizer anti-theft system works
When the ID key is inserted into the ignition and turned to the ON position, the integrated receiver transmits a signal to the satellite transponder. The satellite transponder then transmits an encoded signal back to the integrated receiver.
Next, this part will transmit the encoded signal to the ECM/PCM and MICU. The ECM/PCM and MICU will recognize this encoded signal. If the signal matches, it will supply voltage to control the fuel pump and ignition to start the engine. If the signal does not match, it will prevent the engine from starting.
