TIAGO TIGOR BSVI - SERVICE MANUAL

SUPPLEMENTARY RESTRAINT SYSTEM (SRS) AB12 12 8. COMPONENTS 8.1. RESTRAINT WITHOUT AIRBAGS Restraints system without airbags consists of following main components:  Seat Belt.  Emergency Locking Retractor (ELR).  Micro-switch (inside seat belt buckle). A. SEAT BELT With these seat belts, occupants have to buckle the seat belts before starting to drive the vehicle. B. EMERGENCY LOCKING RETRACTOR (ELR) It is a locking mechanism that is activate in following conditions:  When a sudden deceleration is sensed.  When the seat belt webbing pull-out speed exceeds a threshold value.  When one side of the vehicle is more inclined than the other side. E.g. If one of the vehicle tyre goes off-road during driving. C. MICRO-SWITCH / SEAT BELT REMINDER WARNING LAMP Micro switch is a device which indicates the whether the seat belt is worn or not. This switch activates the warning light (which is in the instrument cluster ) if the seat belts are not buckled properly or not worn. 8.2. RESTRAINT WITH AIRBAGS A. ECU The SRS ECU gets power supply from vehicle ignition and is design to perform the following functions in the air bag system: FUNCTIONS CRASH DETECTION SRS ECU monitors vehicle deceleration levels to detect crashes, and decide if they are severe enough to warrant deployment. AIR BAG DEPLOYMENT When sensors detect a frontal crash of sufficient severity, and send signals to the SRS ECU, which in turn take deployment decision and causes enough current to flow to the air bag (inflator) modules to deploy them. Once Crash is detected, Airbag ECU publishes Crash out Signal to CAN bus to BCM and EMS. BCM then enables door unlock and EMS performs fuel Cut-Off. AIRBAG WARNING LAMP CONTROL AFTER FIRST CRASH: “AIR BAG” warning lamp is turned and kept ON. Once Airbag firing signal is given, ECU cannot be reset using diagnostic tester. Once Airbag ECU fires the restraint components, ECU is lock and should be replaced. Refer post-accident procedures for details ENERGY RESERVE SRS ECU maintains a specific amount of reserve energy supply to provide deployment energy after ignition voltage is lost only during crash. However, the energy reserve is for a limited and short duration, therefore battery terminals and its connection to airbag ECU needs to be check.