Supplemental Inflatable Restraint (SIR)

Wiring Diagram:

CIRCUIT DESCRIPTION
During the Initiator Assembly Resistance Test" the DERM grounds the "Driver Side Low" terminal "B8" and turns "ON" the driver current source at the "Driver Side High" terminal "B9." During this test the DERM monitors voltage at "Driver Side Low" and the difference between "Driver Side High" and "Driver Side Low. When the measured values are outside the expected range DTC 28 is set.

DTC WILL SET WHEN
The voltage measured at "Driver Side Low" is below a specified value while its initiator resistance is in range or when the voltage measured at "Driver Side Low" is above a specified value. This test is run once each ignition cycle during the "Initiator Assembly Resistance Test" when: 1) No "higher priority faults" are detected during "Turn-ON," 2) No "higher priority faults" are detected during "Continuous Monitoring" for one second, 3)No "Crank" signal present, 4) "Ignition 1" voltage is above a specified value.

ACTION TAKEN
The DERM turns "ON" the "AIR BAG" warning lamp and sets a diagnostic trouble code.

DTC WILL CLEAR WHEN
The ignition switch is turned "OFF."

DTC CHART TEST DESCRIPTION
None.

DIAGNOSTIC AIDS
During the "Initiator Assembly Resistance Test" the DERM checks for proper resistance of CKT 347A, CKT 348A, the SIR coil assembly and the inflator module. This test is performed by causing a known amount of current through a known amount of resistance causing a known amount of voltage at "Driver Side Low. " When the measured resistance is in range and the voltage at "Driver Side Low" is too high or too low, DTC 28 is set.