Supplemental Inflatable Restraint (SIR)

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION
When the ignition switch is turned to "RUN," the SDM will perform tests to diagnose critical malfunctions within itself. Upon passing these tests, "Ignition 1," 23 VLR, and deployment loop voltages are measured to ensure they are within their respective normal voltage ranges. The SDM then proceeds with the "Resistance Measurement Test." "Driver Side Low" terminal "3" is grounded through a current sink and the driver current source connected to "Driver Side High" terminal "2" allows a known amount of current to flow. By monitoring the voltage difference between "Driver Side High" and "Driver Side Low" the SDM calculates the combined resistance of the driver inflator module, SIR coil assembly, harness wiring CKTs 347 and 348 and connector terminal contact.

DTC WILL SET WHEN
The combined resistance of the driver inflator module, SIR coil assembly, harness wiring CKTs 347 and 348 and connector terminal contact is below 1.7 ohms. This test is run during the "Resistance Measurement Test" when: 1) No "higher priority faults" are detected during "Turn-ON," 2) "Ignition 1" voltage is above 8.2 volts.

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

DTC WILL CLEAR WHEN
The malfunction is no longer present and the ignition switch is cycled.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. Recording "Driv. Resist." before disturbing the system provides a baseline value in case the malfunction turns out to be intermittent.
2. This test verifies proper connection of the driver inflator module yellow 2-way connector and isolates the low resistance to either the driver inflator module/SIR coil assembly, or CKTs 347 and 348.
3. A decrease in driver deployment loop resistance has been detected. This test checks for a short from CKT 347 to 348.
4. This test checks for a short from CKT 347 to 1404.
5. This test isolates the malfunction to either the driver inflator module or the SIR coil assembly.

DIAGNOSTIC AIDS
An intermittent condition is likely to be caused by a short from CKT 347 to CKT 348, 1403 or 1404, or a malfunctioning shorting bar on the driver inflator module or SIR coil assembly, which would require replacement of the component. The test for this diagnostic trouble code is only run while "AIR BAG" warning lamp is performing the "BULB TEST." When a scan tool "Clear Codes" command is issued and the malfunction is still present, the DTC will not reappear until the next ignition cycle.