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SUPPLEMENTARY RESTRAINT SYSTEM (SRS)
9
SRS
11.1.6.2 RESTRAINT WITH AIRBAGS
11.1.6.2.1 ECU
The SRS ECU
gets power supply from vehicle
battery
and
is designed to perform the following
functions in the air bag system:
FUNCTIONS
ENERGY RESERVE
SRS ECU
maintains a Reserve energy supply to
provide deployment energy after ignition voltage is
lost during crash. However, the energy reserve is for
a limited duration, therefore battery terminals and its
connection to airbag ECU needs to be checked.
CRASH DETECTION
SRS ECU
monitors vehicle deceleration levels to
detect crashes which are severe enough to warrant
deployment.
AIR BAG DEPLOYMENT
When sensors detect a frontal crash of sufficient
severity, they send signals to the SRS ECU which in
turn causes enough current to flow to the air bag
(inflator) modules to deploy them.
LAMP CONTROL AFTER FIRST CRASH
“AIR BAG” warning lamp is turned and kept ON. Re-
set this memory mode using diagnostic tester. ECU
needs replacement if it has sensed a crash.
MALFUNCTION DETECTION
The SRS ECU performs diagnostic monitoring of the
air bag system electrical components and switches
on the indication on instrument cluster and sets a
diagnostic trouble code when a malfunction is de-
tected.
MALFUNCTION DIAGNOSIS
SRS ECU displays air bag diagnostic trouble codes
and system status information through the use of
diagnostic tool.
“AIR BAG” WARNING LAMP
A warning indicator in instrument cluster will alert for
any malfunction of the airbag “SRS”. Under normal/
fault free condition, the air bag warning light comes
“ON” for approximately 3 seconds and goes “OFF”
when ignition is turned ON.
LOCATION
Airbag ECU is mounted on the floor tunnel along the
centre line of the vehicle under the floor console.