An immobilizer is installed on Renault Logan cars - an electronic device designed to prevent unauthorized starting of the engine by breaking the electrical circuits of the engine control system.
The immobilizer consists of a control unit, a communication coil in the ignition lock (transponder rings), keys and control lamp in the instrument cluster. The immobilizer operating modes are displayed by turning on the signal lamp.
The immobilizer control unit is connected to the controller via the diagnostic line. The control unit includes a built-in relay that connects the diagnostic block to the controller or disables it. If a diagnostic tool is not connected to the diagnostic block, the relay opens the diagnostic circuit and the line is used to communicate with the controller and the control unit. When the device is connected to the diagnostic block, the relay closes the diagnostic circuit, which allows the exchange of information between the device and the controller. However, the immobilizer control unit has priority over the diagnostic tool when working with the controller, if necessary, the control unit interrupts the connection between the controller and the tool (for example, to exchange information between the control unit and the controller when starting the engine).