DTC 21

Wiring Diagram:

CIRCUIT DESCRIPTION

When the ignition switch is turned to "ON," 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 "10" is grounded through a current sink and the driver current source connected to "Driver Side High" terminal "9" 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 G/R and G and connector terminal contact.

DTC WILL SET WHEN

The combined resistance of the driver inflator module, SIR coil assembly, harness wiring CKTs G/R and G and connector terminal contact is above 4.0 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 ignition switch is cycled.

DTC CHART TEST DESCRIPTION

Numbers below refer to circled numbers on the diagnostic chart.

1. Recording "Driv. Resist." after each ignition to "ON" may help to locate the fault. The Pass. Resist. value is updated each ignition cycle.

2. This test verifies proper connection of the yellow 2-way connector at the base of the steering column.

3. This test checks for proper contact and/or corrosion of the yellow 2-way connector at the base of the steering column.

4. This test isolates the malfunction to one side of the driver inflator module yellow 2-way connector located at the base of the steering column.

5. This test determines whether the malfunction is due to increased resistance in the wiring. The J39200 is normally in the high resolution mode.

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 poor connection at terminals "D3" and "D4" of the SIR coil connector at the base of the steering column, terminals "D1" and "D2" of the driver inflator module connector at the top of the steering column, SDM terminals "9" and "10" or a poor wire to terminal connection in CKT G/R or CKT G. The test for this diagnostic trouble code is only run while the "AIR BAG" warning lamp is performing the bulb check unless a higher priority fault code 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.