Supplemental Inflatable Restraint (SIR)

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION
During normal, non-deployment operation of the SIR system, a small amount of current flows through both the driver and passenger deployment loops. The diagnostic resistors within the dual pole arming sensor and the discriminating sensors along with the resistance of the inflator modules cause voltage drops within the deployment loops. The DERM monitors the voltage at "Driver Side Low" terminal "B8" to detect shorts or opens within the driver deployment loop. When the measured voltage is above a specified percentage of "Driver 36 VLR" for 500 milliseconds DTC 23 is set.

DTC WILL SET WHEN
The voltage measured at "Driver Side Low" terminal "B8" is above a specified percentage of "Driver 36 VLR" for 500 milliseconds and DTC 35 is not set. This test is run during the "Continuous Monitoring" tests.

ACTION TAKEN
DERM sets a diagnostic trouble code and sends a command to the instrument cluster to turn "ON" the "AIR BAG" warning lamp.

DTC WILL CLEAR WHEN
The voltage measured at "Driver Side Low" terminal "B8" is within a specified percentage of "Driver 36 VLR" for 500 milliseconds.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. DTC 23 and 24 together means that there is an open between the steering column harness connector and the passenger compartment discriminating sensor.
2. This test determines whether the malfunction is an open in CKT 348B.

DIAGNOSTIC AIDS
An open between the driver inflator module harness connector and the discriminating sensor interconnect causes the voltage to increase at "Driver Side Low" due to the loss of a ground path. This also causes the voltage to decrease at "Passenger Side Low" due to decreased current flow through the discriminating sensor network. Refer to DTC 19 to diagnose history DTC 23 without history DTC 24. Supplemental Inflatable Restraint (SIR)