DTC 21

Test K: DTC 21 Driver Initiator Circuit Resistance High:

Supplemental Inflatable Restraint (SIR):

OPERATION:
During the "Initiator Assembly Resistance Test" the DERM grounds the "Passenger Side Low" terminal "B7" and turns "ON" the driver current source at the "Driver Side High" terminal "B9." This causes a known amount of current to flow through the Driver Initiator Circuit. By monitoring the difference between the voltage at the "Driver Side High" terminal "B9" and the "Driver Side Low" terminal "B8" the DERM calculates the combined resistance of the Driver Inflator Module, SIR Coil Assembly, harness wiring CKTs 347A and 348A and connector terminal contact.

Test Conditions: Tested once each ignition cycle during the "Initiator Assembly Resistance Test" when: 1) No "higher priority faults" are detected during "Turn-ON" 2) No "higher priority faults" are detected during Continuous Monitoring" for 1 second, 3) No "CRANK" signal present, 4) "Ignition 1" voltage is above a specified value.

Failure Conditions: DTC 21 will set when the combined resistance of the Driver Inflator Module, SIR Coil Assembly, harness wiring CKTs 347A and connector terminal contact is above a specified value.

Action Taken: DERM turns "ON" the "INFLATABLE RESTRAINT" warning lamp and sets a Diagnostic Trouble Code.

Conditions to Clear: DTC 21 will clear each time the ignition switch is turned "OFF."

POSSIBLE CAUSES:
Test Description: Number(S) below refer to circled number(S) on the diagnostic chart.
1. This test determines whether the malfunction is in the Driver Inflator Module circuitry or in the DERM wiring harness circuitry.
2. This test determines if the malfunction is an open in CKT 347A.
3. This test determines whether the malfunction is in the Driver Inflator Module or the SIR Coil Assembly.

DIAGNOSTIC AIDS:
An intermittent condition is likely to be caused by a poor connection at: the yellow 2-way connector near the base of the steering column, DERM terminals "B8" or "B9," or the connection at the top of steering column to the driver inflator module.