Supplemental Inflatable Restraint (SIR)

When measurements are requested in this chart, use SA 911 14NE DVM with correct terminal adapter from SA 9206Z. When a check for proper connection is requested, refer to "Intermittents and Poor Connections." When a wire connector or terminal repair is requested, use the proper repair parts and refer to "Wiring Repair."

CAUTION: BEFORE PERFORMING DIAGNOSTICS, THE IGNITION SWITCH MUST BE IN THE "OFF" POSITION FOR 10 MINUTES (REFER TO DISABLING AND ENABLING PRECAUTIONS).

NOTICE: Perform "SIR DIAGNOSTIC SYSTEM CHECK" before proceeding with this chart. SIR Diagnostic System Check

CIRCUIT DESCRIPTION
When the ignition switch is turned On, the Sensing and Diagnostic Module (SDM) will perform tests to diagnose critical malfunctions within itself. Upon passing these tests "Ignition 1," VLR, and deployment loop voltages are measured to ensure they are within their respective normal voltage ranges. The SDM then proceeds with the "Current Source Diagnostics." "Driver Side LO" terminal A3 is grounded through a resistor and the driver current source connected to "Driver Side HI" terminal A2 allows a known amount of current to flow. By monitoring the voltage difference between "Driver Side HI" and "Driver Side LO" the SDM calculates the combined resistance of the driver inflator module, SIR coil assembly, harness wiring circuits 347 and 348 and connector terminal contact.

DTC WILL SET WHEN:
The combined resistance of the driver inflator module, SIR coil assembly, harness wiring circuits 347 and 348 and connector terminal contact is less than 1.2 ohms. This test is run during the "Current Source Diagnostics" when:
1. No "higher priority faults" are detected during "Turn-On,"
2. No "higher priority faults" are detected during "Continuous Monitoring,"
3. "Ignition 1" voltage is above a specified value.

ACTION TAKEN:
SDM turns On the AIR BAG telltale lamp and sets DTC 22.

DTC WILL CLEAR WHEN:
The malfunction is no longer occurring and the ignition switch is turned Off, or a Scan tool "Clear Codes" command is issued.

DTC CHART TEST DESCRIPTION:
Number(s) below refer to step number(s) on the diagnostic chart.
Step 1. DTC 16 and 22 will set simultaneously when the "Driver Side HI" circuit is shorted to the "Passenger Side HI" circuit due to parallel current paths.
Step 3. This test determines whether the malfunction is in the driver inflator module circuitry or in the SDM wiring harness circuitry.
Step 4. This test checks for a short from the "Driver Side HI" circuits to the "Driver Side LO" circuit.
Step 5. This test determines whether the malfunction is in the driver inflator module or the SIR coil assembly.
Step 6. This test checks for a short from the "Driver Side HI" circuit to the "Passenger Side LO" circuit.

DIAGNOSTIC AIDS:
An intermittent condition is likely to be caused by a short between circuits 347 and 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 the AIR BAG telltale lamp is performing the bulb check, unless DTC 17 or 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.