Supplemental Inflatable Restraint (SIR)

Wiring Diagram:

CIRCUIT DESCRIPTION
During normal, non-deployment operation of the SIR system, the DERM monitors the voltage supplied through the arming sensor to the high side of the driver deployment loop at the "Driver Source Sense" terminal "A5." This measured voltage will have a value approximately equal to "Driver 36 VLR." When the voltage measured at "Driver Side Low" terminal "B8" is in its normal operating range, indicating driver deployment loop integrity has been maintained, while simultaneously the voltage measured at "Driver Source Sense" terminal "A5" is a specified amount below "Driver 36 VLR" for 500 milliseconds, DTC 43 is set.

DTC WILL SET WHEN
The voltage measured at "Driver Side Low" terminal "B8" is within a specified percentage of "Driver 36 VLR" while simultaneously the voltage measured at "Driver Source Sense" terminal "A5" is a specified amount below "Driver 36 VLR" for 500 milliseconds during "Continuous 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" while simultaneously the voltage measured at "Driver Source Sense" terminal "A5" is within a specified amount of "Driver 36 VLR" for 500 milliseconds during "Continuous Monitoring."

DTC TABLE TEST DESCRIPTION
Number(s) below refer to step number(s) on the diagnostic table.
1. The "SIR DIAGNOSTIC SYSTEM CHECK" must be the starting point of all diagnostics.
12. This test checks for an open in "Driver Source Sense" circuit.
15. This test locates the open in "Driver Source Sense" circuit.
18. This test checks for a short from the "Driver Source Sense" circuit to ground.
19. This test locates the short from the "Driver Source Sense" circuit to ground.
22. The test determines if the malfunction is due to increased resistance across the "Driver Source Sense" resistor in the arming sensor.

DIAGNOSTIC AIDS
An intermittent condition is likely to be caused by a poor connection to the DERM at terminal "A5," a poor connection to the arming sensor or arming sensor jumper harness electrical connector at terminal "C," an open or short to ground in CKT 1400 or an open arming sensor.