Component Tests and General Diagnostics
Sensing and Diagnostic Module Integrity Check
The following diagnostic procedure must be used when all circuitry outside the sensing and diagnostic module (SDM) has been found to operate properly, as indicated by following the appropriate DTC table. The procedure verifies the need for SDM replacement.
Circuit Description
When the SDM recognizes ignition voltage greater than 9 volts at the SDM, the air bag indicator flashes 7 times to verify operation. At this time the SDM performs turn-on tests followed by resistance measurement tests and continuous monitoring tests.
When malfunction is detected, the SDM sets a current DTC and illuminates the air bag indicator.
When the malfunction is no longer detected and/or the ignition switch is cycled, the SDM will clear current DTCs and move them to a history file, except for the DTCs B1620, B1650, B1651, B1652, B1657. DTCs B1620, B1650, B1651, B1652, B1657 will not be cleared by a scan tool because these codes require replacement of the SDM. The SDM must be replaced only after the malfunction that set the DTC has been repaired.
Test
