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 above 3.8 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 checks for a high resistance within the connector.
3. This test isolates the high resistance to either the driver inflator module/SIR coil assembly, or CKTs 347 and 348.
4. A high resistance has been detected in CKTs 347 and/or 348. This test checks CKT 347 for high resistance.
5. This test checks CKT 348 for high resistance.
6. If the malfunction cannot be found in the external wiring, the SDM may be malfunctioning.
7. If the SIR coil assembly pigtail connector terminals are damaged or corroded, the SIR coil assembly must be replaced.
8. 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 poor connection at terminals "A" or "B" of the SIR coil connector at the base of the steering column, terminals "A" or "B" of the driver inflator module connector at the top of the steering column, SDM terminals "2" and "3" or a poor wire to terminal connection in CKT 347 or CKT 348. The test for this diagnostic trouble code is only run while the "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.