Swift GA L4-1298cc 1.3L SOHC MFI (2001)
Sensing and Diagnostic Module: Description and Operation
SENSING AND DIAGNOSTIC MODULE (SDM)
WARNING: During service procedures, be very careful when handling a Sensing and Diagnostic Module (SDM). Never strike or jar the SDM.
Never power up the air bag system when the SDM is not rigidly attached to the vehicle. All SDM and mounting bracket fasteners must be
carefully torqued to ensure proper operation of the air bag system. The SDM could be activated when powered while not rigidly attached to the
vehicle which could cause deployment and result in personal injury.
The Sensing and Diagnostic Module (SDM) is designed to perform the following functions in the air bag system:
1. Energy Reserve - The SDM maintains a reserve energy supply to provide deployment energy when ignition voltage is lost in a frontal crash.
2. Frontal Crash Detection - The SDM monitors vehicle velocity changes to detect frontal crashes which are severe enough to warrant deployment.
3. Air Bag Deployment - When a frontal crash of sufficient force is detected, the SDM will cause enough current to flow through the air bag
(inflator) modules to deploy the air bags.
4. Malfunction Detection - The SDM performs diagnostic monitoring of the air bag system electrical components and sets a diagnostic trouble code
when a malfunction is detected.
5. Malfunction Diagnosis
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The SDM displays air bag diagnostic trouble codes and system status information through the use of special tool (Tech-1, scan tool).
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The SDM provides air bag diagnostic trouble codes by flashing "AIR BAG" warning lamp when on-board diagnosis function is used.
6. Driver Notification - The SDM warns the vehicle driver of air bag system malfunctions by controlling the "AIR BAG" warning lamp.
The SDM is connected to the air bag wiring harness by a 12-way connector. This harness connector uses a shorting bar across certain terminals in
the contact area. This shorting bar connects the "AIR BAG" warning lamp to ground when the SDM harness connector is disconnected.
This will cause the "AIR BAG" warning lamp to come "ON" steady whenever the ignition switch is at the ON or START position with the SDM
disconnected.
