Sedona EX V6-3.5L (2002)
Air Bag Control Module: Description and Operation
The SRS airbag system has sophisticated electrical and electronic components, therefore the airbag operating components should be handled very
carefully.
1. SRSCM (Supplemental Restraint System Control Module)
SRSCM determines to deploy the airbag module by sensing the frontal and side impact sensed by the sensor built in SRSCM.
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DC/DC convertor : The power supply DC/DC converters include a step-up and step-down converter, which provides the firing voltage for two
firing circuits and the internal operating voltage. if the internal operating voltage falls below a defined threshold, a reset is executed.
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Arming sensor/safing sensor : The arming/safing sensor built in 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.
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Back-up power : The SRSCM reserves the energy supply to provide deployment energy for a short second when the vehicle voltage is low or if
lost in a vehicle frontal crash.
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Malfunction detection : The SRSCM continuously monitors the current SRS operation status while the ignition key is turned on and detects the
malfunction of the system. The malfunction can be displayed in the form of diagnostic trouble code using scan tool (Hi-scan).
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MIL (Malfunction Indication Lamp) notification If any fault is detected, the SRSCM sends signal to the indicator lamp on the cluster to warn
the vehicle driver. The MIL indicator is the key to driver notification of SRS faults. Verify lamp and SRSCM operation by flashing 6 times
when the ignition switch is first turned on.
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Malfunction recording : Once a fault occurred in the system SRSCM records the fault in the memory in the form of DTC and the DTC can
only be erased with the scan tool.
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Data link connector The SRSCM memory stored data is accessed through the OBD-II Data Link Connector (DLC) using a scan tool. The DLC
is located underneath the driver side crash pad.
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After firing the airbags once, the SRSCM cannot be used again and must be replaced.
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Crash output
The crash output is used to control an external device such as door control module in case of a crash event.
The crash output is specified as follows : The crash output is open-collector type switch logic output with 500 mA of sine current and its
output impedance is 100 ohm. The crash output is switched to ground for 200 ms after the crash detected.
