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 the driver deployment loop. The diagnostic resistors within the arming sensor and the discriminating sensors along with the resistance of the inflator module cause voltage drops within the deployment loop. The DERM monitors the voltage at "Driver Side Low" terminal "B8" to detect shorts or opens within the deployment loop. When the measured voltage at terminal "BS" is below a specified percentage of "Driver 36 VLR" for 500 milliseconds DTC 24 is set.

DTC WILL SET WHEN
The voltage measured at "Driver Side Low" terminal "B8" is below a specified percentage of "Driver 36 VLR" for 500 milliseconds during "Continues Monitoring."

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

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 during "Continues Monitoring."

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This test determines whether the malfunction is occurring in the steering column circuitry.
2. This test, essentially, determines whether the malfunction is due to a component or the wiring.
3. This test checks for increased resistance of the arming sensor.
4. This test checks for a partial short inside the RH forward discriminating sensor.
5. This test checks for a partial short inside the LH forward discriminating sensor.
6. This test checks for an open in CKT 347B.
7. This test checks for a short from the "Driver Side High" circuit to ground.
8. This test checks for a short from the "Driver Side Low" circuit to ground.
9. This test checks for a short from the discriminating sensor interconnect circuit to ground.
10. This test checks for a short inside the RH forward discriminating sensor.
11. This test checks for a short inside the LH forward discriminating sensor.

DIAGNOSTIC AIDS
An intermittent condition is likely to be caused by a poor connection at DERM terminal "A4," arming sensor terminals "B" or water intrusion in either discriminating sensor, an open in CKT 347B or a short to ground on CKT 347, CKT 348 or CKT 349. Refer to DTC 25 to diagnose a possible short to B+. When the malfunction occurs during an ignition cycle DTC 24 will set. If the malfunction is present at the beginning of the next ignition cycle DTC 25 will set and DTC 24 will be moved to a history file.