1. When the turn switch is in the LH or RH position, the instrument cluster detects (1) a turn switch LH signal or turn switch RH signal.
2. The instrument cluster sends (2) the turn switch LH signal or turn switch RH signal to the body control module (BCM) via CAN communication.
3. When the body control module (BCM) receives the turn switch LH signal or turn switch RH signal with the ignition switched ON (engine off or on), it sends (3) a turn switch LH flash request signal or turn switch RH flash request signal to the door-electrical supply unit via CAN communication.
4. When the door-electrical supply unit receives the turn switch LH flash request signal or turn switch RH flash request signal, it flashes (4) the side turn light (LH) or side turn light (RH).