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" and "Passenger Side Low" terminal "B7" to detect shorts or opens within the deployment loops. When the measured voltage at either terminal is within a specified percentage of its respective "36 VLR" power supply voltage for 500 milliseconds DTC 35 is set.

DTC WILL SET WHEN
The voltage measured at "Driver Side Low" terminal "B8" or at "Passenger Side Low" terminal "B7" is within a specified percentage of its respective "36 VLR" power supply voltage for 500 milliseconds. This test is run every 100 milliseconds during the "Continuous Monitoring" tests.

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

DTC WILL CLEAR WHEN
The voltages measured at "Driver Side Low terminal "B8" and "Passenger Side Low" terminal "B7" are both above or below the percentage of their respective "36 VLR" power supply voltage which sets DTC 35.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chant.
1. This test checks for an open in the forward discriminating sensor between terminal "D" and the splice.
2. This test checks for a high resistance between the passenger inflator module and the forward discriminating sensor.
3. This test checks for an open ground feed to the forward discriminating sensor.
4. This test checks for an open inside the RH mid-rail discriminating sensor.
5. This test checks for an open ground feed to the RH mid-rail discriminating sensor.
6. This test checks for a high resistance between the RH mid-rail discriminating sensor and the forward discriminating sensor.
8. This test checks for increased resistance of the diagnostic resistor in the LH mid-rail discriminating sensor.
9. This test checks for an open ground feed to the LH mid-rail discriminating sensor.
10. This test checks for a high resistance between the driver inflator module and the LH mid-rail discriminating sensor.
11. This test determines whether the malfunction is due to decreased resistance of the diagnostic resistors in the dual pole arming sensor.

DIAGNOSTIC AIDS
An intermittent condition is likely to be an improper connection at any of the discriminating sensor terminals except LH mid-rail discriminating sensor terminal "B" or RH mid-rail discriminating sensor terminal "A," an open ground feed to the discriminating sensors, an open discriminating sensor interconnect circuit, a malfunctioning discriminating sensor or a malfunctioning dual pole arming sensor.