Circuit Description
WARNING: This page is about a different car, the 2002 Buick Regal and 2002 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
Side Impact Sensor (SIS) utilizes a unidirectional 2-circuit wire. SIS modulates current on the interface to send identification, State Of Health (SOH) and deployment commands to Sensing and Diagnostic Module (SDM). SDM serves as a power source and ground for SIS. When ignition is turned on and input power from SDM is first detected, SIS performs internal diagnostics, then sends an identification message to SDM. SDM considers this a valid message if response time is less than 5 seconds. SIS continually communicates a status message to SDM, which determines if a fault is present in SIS circuit. When a fault is detected, SDM resets SIS twice by removing and reapplying power to SIS. If fault is still present, SDM will set appropriate DTC.