SRC-12
< SYSTEM DESCRIPTION >
SYSTEM
Supplemental Restraint System (SRS) activates air bag module and seat belt pre-tensioner when it detects a
frontal collision or a side collision that is more than the specified limit. Together with other safety devices, it
reduces the impact that occupant receives when vehicle collision occurs. Air bag diagnosis sensor unit sup-
plies power supply to air bag module and pre-tensioner seat belt when deceleration that is more than the
specified limit is detected by G sensor in air bag diagnosis sensor unit, crash zone sensor, satellite sensor. Air
bag module is composed of electric igniter (squib), filter, pyrotechnic material, and gas generating material.
When air bag module receives a signal from air bag diagnosis sensor unit, air bag module ignites pyrotechnic
material using electric igniter (squib) so that gas generating material generates high temperature nitrogen gas.
The gas through filter activates air bag. At the same time, pre-tensioner seat belt receives power supply from
air bag diagnosis sensor unit, gas generator is activated, and then gas is generated. Balls in pipe are moved
according to generated gas pressure and strike pinion gear on ELR shaft. ELR shaft rotates and retracts seat
belt.
AIR BAG DIAGNOSIS SENSOR UNIT FUNCTIONS
Air bag diagnosis sensor unit has the following functions.
• Detects a collision and supplies the energy for deploying air bag and seat belt pre-tensioner.
• Detects and records electrical malfunction in air bag system and seat belt pre-tensioner system, and turns
air bag warning lamp ON.
• Detects and records the deployment of air bag and seat belt pre-tensioner, and turns ON air bag warning
lamp.
• Indicates the malfunction record via CONSULT.
• Transmits car crash information signal to BCM when a collision is detected (collision detection output func-
tion).
Air Bag Warning Lamp
• Detects electrical malfunction in air bag system and seat belt pre-tensioner system, and turns air bag warn-
ing lamp ON.
• Detects deployment malfunction in air bag system and seat belt pre-tensioner system, and turns air bag
warning lamp ON.
• Air bag diagnosis sensor unit warns the driver by turning air bag warning lamp ON when air bag diagnosis
sensor unit detects battery low voltage. Air bag warning lamp turns ON when a voltage value at which air
bag diagnosis sensor unit cannot operate normally (9 V or less) is detected for 10 seconds or more. After
starting to turn ON, air bag warning lamp turns OFF when air bag diagnosis sensor unit detects the normal
value of battery voltage for 10 seconds or more. The mode cannot be switched to diagnosis mode by ignition
switch while air bag warning lamp turns ON due to this cause.
• Air bag diagnosis sensor unit warns the driver by turning air bag warning lamp ON when air bag diagnosis
sensor unit detects battery high voltage. Air bag warning lamp turns ON when a voltage value at which air
bag diagnosis sensor unit cannot operate normally (16 V or more) is detected for 3 seconds or more. After
starting to turn ON, air bag warning lamp turns OFF when air bag diagnosis sensor unit detects the normal
value of battery voltage for 3 seconds or more. The mode cannot be switched to diagnosis mode by ignition
switch while air bag warning lamp turns ON due to this cause.