How does a car's immobilizer system function?

@janis.feest 

A car's immobilizer system functions by preventing the engine from starting without the authorized key or remote being present. The system consists of a transponder chip, an engine control unit (ECU), and an antenna.

1. Transponder chip: The key or remote contains a tiny embedded microchip known as a transponder. The transponder chip emits a unique electronic code when in proximity to the car's ignition system.
2. Antenna: The car's ignition system is equipped with an antenna that detects the presence of the transponder chip when it is placed near the ignition switch.
3. Engine Control Unit (ECU): The ECU is the main control unit of the car's immobilizer system. It communicates with the transponder chip and the ignition system to ensure that only the correct authorized key or remote can start the engine.

Here's how the system works:

1. When the key or remote is inserted or used near the ignition switch, the antenna picks up the unique electronic code emitted by the transponder chip.
2. The antenna sends this code to the ECU for verification.
3. The ECU compares the received code with the authorized codes stored in its memory. If the code matches, the ECU sends an authorization signal to the ignition system, allowing the engine to start.
4. If the code does not match or no code is detected, the ECU sends a signal to disable the fuel pump or ignition system, preventing the engine from starting.

In simple terms, the immobilizer system ensures that only a key or remote with the correct transponder chip can start the engine, providing an additional layer of security against theft.

@janis.feest 

A car's immobilizer system is designed to prevent unauthorized individuals from starting and operating the vehicle. The system works through a combination of electronic components and programming.

1. Transponder Key: The car's immobilizer system is typically integrated into the vehicle's key. The key contains a small chip known as a transponder that emits a unique code when it is in close proximity to the car's ignition.
2. Immobilizer Control Unit: The car contains an immobilizer control unit that receives and processes the code emitted by the transponder key.
3. Authentication Process: When the key is inserted into the ignition, the immobilizer control unit sends a signal to the key, prompting it to emit the transponder code. The control unit then compares this code to a pre-programmed set of codes stored within its memory.
4. Authorization: If the transponder code matches one of the stored codes, the immobilizer control unit sends a signal to the engine control unit (ECU) allowing the vehicle to start. If there is no match, the control unit will prevent the engine from starting by disabling the ignition or fuel system.
5. Anti-Theft Deterrence: In addition to preventing unauthorized ignition, the immobilizer system remains active even when the vehicle is parked and turned off. This acts as a deterrent against thieves who may attempt to hotwire the car or steal it using unauthorized keys.

It is important to note that the specific details and components of a car's immobilizer system can vary between different makes and models.