SDM (Sensing and Diagnostic Module)

SDM (SENSING AND DIAGNOSTIC MODULE)

WARNING:
- During service procedures, be very careful when handling a Sensing and Diagnostic Module (SDM).
- Be sure to read "SERVICE PRECAUTIONS" and "HANDLING PRECAUTIONS" before starting to work and observe every precaution during work. Neglecting them may result in personal injury or undeployment of the air bag when necessary.

CAUTION: After detecting one time of such collision as to meet deployment condition, the SDM must not be used. Replace with new one.

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 after ignition voltage lost in a frontal crash.
2) Frontal Crash Detection
- The SDM monitors vehicle velocity changes to detect frontal crashes which are severe enough to war- rant deployment.
3) Air Bag Deployment
- When a frontal crash of sufficient force is detected, the 5DM will cause enough current to flow through the air bag (inflator) modules to deploy the air bags.
4) Frontal Crash Recording
- The SDM records information regarding the air bag system status during a frontal crash.
5) Malfunction Detection
- The SDM performs diagnostic monitoring of the air bag system electrical components and sets a diagnostic trouble code (DTC) when a malfunction is detected.
6) Malfunction Diagnosis
- The SDM displays air bag diagnostic trouble codes (DTCs) and system status information through the use of special tool (Tech-1, scan tool).
- The SDM with on-board diagnostic function provides air bag diagnostic trouble codes by flashing "AIR BAG" warning lamp when on-board diagnosis function is used.
7) "AIR BAG" Warning Lamp Control
- The light is turned "ON" to warn the driver of occurrence of a trouble and made to flash to check the burned bulb of "AIR BAG" warning lamp.
8) Communication with Tech-1
- DTC display or DTC clear.
- In response to the output request from Tech-1, DTC recorded in the memory, each initiator circuit resistance and ignition voltage as recognized by SDM at time of the output request are provided.