The SRS (Airbag)
consists of : a driver airbag module located in the center of the steering
wheel, which contains a folded cushion and an inflator unit ; a passenger
airbag module located in the passenger side crash pad which contains a
folded cushion together with an inflator unit ; side airbag modules
located in the driver and passenger seat which contain folded cushions and
inflator units; SRSCM located on the floor center console core which
monitors the system,; an accelerometer which senses vehicle deceleration,;
a spring interconnection (clock spring) located within the steering
column; system wiring and wiring connectors; and a knee bolster located
under the steering column. The impact sensing function of the SRSCM is
carried out by the electronic accelerometer that continuously measures the
vehicle's acceleration and delivers a corresponding signal through an
amplifying and filtering circuit to the microprocessor. Deployment of the
airbag is designed to occur in frontal or near-frontal side impacts of
moderate to severe force.
CUSTOMER CAUTIONS
Further, if a mistake is
made in servicing the airbag system, it is possible that the airbag may
fail to operate when required.
1. |
Be sure to proceed with airbag related service
only after approx. 30 seconds or longer from the time the ignition
switch is turned to the LOCK position and the negative (-) terminal
cable is disconnected from the battery. The airbag system is
equipped with a back-up power source to assure the deployment of
airbags when the battery cable is disconneted during an accident.
The back-uppower is available for approx.
150ms. |
2. |
When the negative(-) terminal cable is
disconnected from the battery, the clock and audio system's memory
will be wiped out. So before starting work, make a record of the
contents of the audio system's memory. When the work is finished,
reset the audio system and adjust the
clock. |
3. |
Symptoms of malfunction of the airbag system
are difficult to detect, so the diagnostic codes become the most
important source of information when
troubleshooting. |
4. |
When troubleshooting the airbag system, always
inspect the diagnostic codes before disconnecting the
battery. |
5. |
Never use airbag parts from another vehicle.
When replacing parts, replace them with new
parts. |
6. |
Never attempt to disassemble and repair the
airbag modules (DAB, PAB, SAB, BPT), clock spring and wiring in
order to reuse them. |
7. |
If any component of SRS has been dropped, or
if there are cracks, dents or other defects in the case, bracket or
connector, replace them with new
ones. |
8. |
After work on the airbag system is completed,
perform the SRS SRI check. The airbag indicator lamp can be
triggered by faults in other circuit in some cases. Therefore if the
airbag indicator lamp goes on, be sure to erase the DTC codes using
Hi-scan just after repairing or replacing the troubled
parts,including the fuse. |
9. |
Especially when carring out body welding,
never fail to disconnect the battery's negative (-)
terminal. |
SRSCM
The SRS airbag system
has sophisticated electrical and electronic components. Therefore the
airbag operating components should be handled very carefully.
The SRSCM will deploy
the airbag modules by sensing the frontal impact sensed by the sensor
built in to the SRSCM.
1. |
DC/DC convertor : The DC/DC converter in the
power supply includes a step-up and a step-down converter, which
provides the firing voltage for four firing circuits and the
internal operating voltage. If the internal operatingvoltage falls
below a defined threshold, a reset is
executed. |
2. |
Arming sensor/safing sensor : The
arming/safing sensor built in to the airbag firing circuit has the
function of arming the airbag circuit under all required deployment
conditions and maintaining the airbag firing circuits unarmed under
normal driving conditions. The safing sensor is a dual-contact
electromechanical switch that closes if it experiences a
deceleration exceedinga specified
threshold. |
3. |
Back-up power : The SRSCM reserves an energy
reserve to provide deployment energy for a short period when the
vehicle voltage is low or if lost in avehicle frontal
crash. |
4. |
Malfunction detection : The SRSCM continuously
monitors SRS operating status while the ignition key is turned on
and detects possible malfunctions in the system. The malfunction can
be displayed in the form of a diagnostictrouble code using the
Hi-Scan Pro. |
5. |
MIL (Malfunction Indication Lamp) notification
: If any fault is detected, the SRSCM sends a signal to the
indicator lamp on the instrument cluster towarn the vehicle
driver.
The MIL indicator is the key item in notifying
the driver of SRS faults. It verifies lamp and SRSCM operation by
flashing 6 times when the ignitionswitch is first turned
on. |
6. |
Malfunction recording : Once a fault occurs in
the system, the SRSCM records the fault in memory in the form of a
DTC, which can only be erasedby the Hi-Scan
Pro. |
7. |
Data link connector : SRSCM memory stored is
linked through this connector located underneath the driver side
crash pad to an external output devicesuch as the Hi-Scan
Pro. |
8. |
What if only BPT's
deploy |
9. |
Crash output
The crash output is used to unlock the doors
in case of a crash. The crash output is : 0-200 λA in OFF mode and
200mA in ON mode. During theunlock command, the switch is closed for
200 mS. |
SRSCM (SUPPLEMENTAL RESTRAINTS SYSTEM CONTROL
MODULE)
1. |
When removing the airbag module or handling a
new airbag module, it should be placed with the pad top surface
facing up. In this case, the twin-lock type connector lock lever
should be in the locked state and care should be taken to place it
so the connecter will not be damaged. Do not store a steering wheel
pad on top of another one. (Storing the pad with its metallic
surface up may lead to a serious accident if the airbag should
inflate accidentally.) |
2. |
Never measure the resistance of the airbag
squib. (This may cause the airbag to deploy, which is very
dangerous.) |
3. |
Store the airbag module where the ambient
temperature remains below 93°C (200°F), without high humidity and
away from electrical noise. |
4. |
During electric welding, disconnect the airbag
under the steering column near the MULTI-FUNCTION SWITCH connector
before starting
work. |