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ELECTRICAL SYSTEM
1. DC/DC converter : The DC/DC converters of the power supply includes a step up and a step down
converter, which provide the firing voltage for six firing circuits and the internal operating voltage. If the
internal operating voltage 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 which closes if it experiences a deceleration exceeding a specified threshold.
3. Back-up power : The SRSCM has emergency energy reserves to provide deployment energy for a
short period when the vehicle voltage is low or if lost in a vehicle frontal crash.
4. Malfunction detection : The SRSCM continuously monitors the current SRS operation status while the
ignition key is turned on and detects a malfunction of the system. The malfunction can be displayed in
the form of diagnostic trouble code using Hi-scan.
5. MIL (Malfunction Indication Lamp) notification : If any fault is detected, the SRSCM sends a signal to
the indicator lamp on the cluster to warn the vehicle's driver.
The MIL indicator is the key to driver notification of SRS faults. Verify lamp and SRSCM operation by
observing the flashinging 6 times when the ignition switch is first turned on.
6. Malfunction recording : Once a fault occurrs in the system SRSCM records the fault in the memory in
the form of DTC and the DTC is erased by Hi-scan.
7. Data link connector : The SRSCM memory stored data are linked through this connector located at the
underneath of driver side crash pad to an external output device such as Hi-scan.
8. After firing the airbags once, the SRSCM cannot be used again and must be replaced.
9. Crash output
The crash output is used to control an external device which will unlock the doors in case of a crash
event.
SRS HARNESS
SRSCM INDEPENDENT LAMP ACTIVATION
1. Loss of ignition voltage supply to the SRSCM : lamp turns on continuously.
2. Loss of internal operating voltage : lamp turns on continuously.
3. SRSCM not connected : lamp turns on through shorting bar in wiring harness connector.
MIL OPERATING METHOD
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