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 a specified value.

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

DTC WILL CLEAR WHEN
The resistance of the driver deployment loop is more than the specified value and the ignition switch has been cycled.

DTC CHART TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This test determines the deployment loop resistance measured by the SDM.
2. This test verifies proper connection of the yellow 2-way connector.
3. This test isolates the malfunction to one side of the driver inflator module yellow 2-way connector located near the base of the steering column.
4. This test checks for a short from the "Driver Side High" circuit to the "Driver Side Low" circuit.
5. This test checks for a short from the "Driver Side High" circuit to the "Passenger Side Low" circuit.
6. This test determines whether the malfunction is in the SIR coil assembly or the driver inflator module.

DIAGNOSTIC AIDS
An intermittent condition is likely to be caused by a short between CKT 347 and CKT 348 or CKT 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 the "AIR BAG" warning lamp is performing the BULB TEST, unless DTC 17 or DTC 26 is detected. 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.