DTC 21 and 22

CIRCUIT DESCRIPTION
The DERM injects a current through the steering column from the "Force High" output, terminal "A4," to the "Force Low" output, terminal "A10." By monitoring the difference between the voltage at the "Sense High" input, terminal "A7," and the "Sense Low" input, terminal "A6," the DERM calculates the combined resistance of the inflator module, SIR coil assembly, deployment loop and connector terminal contact in the steering column.

TEST CONDITIONS
Tested once each ignition cycle during the "Steering Column Resistance Test" if: 1) No faults are detected during the "Turn-ON Tests"; 2) No faults are detected during the "Continuous Monitoring Tests" for one second; 3) No "Crank" signal present; 4) "Ignition 1" voltage is present,

FAILURE CONDITIONS
DTCs 21 and 22 will set if the voltage at the "Sense Low" input, terminal "A6," is less than a certain voltage during the "Steering Column Resistance Test," This results in an undetermined steering column circuit resistance,

ACTION TAKEN
The DERM illuminates the "INFL REST" indicator.

CONDITIONS TO CLEAR
Current DTCs 21 and 22 will be cleared each time the ignition switch is turned to "OFF."

TEST DESCRIPTION:
Number(s) below refer to circled number(s) on the diagnostic chart,
1. This test checks the integrity of the 49,9 ohm resistor, 100 ohm resistor, 430 ohm resistor and associated circuitry in the resistor module,
2. This test checks for an open in the "Force High" resistor circuitry in the resistor module,
3. This test checks for a short from the "Force Low" CKT 688 to CKT 340,
4. This test checks for a short from the "Force Low" CKT 688 to CKT 349
5. This test checks for a short from the "Force Low" CKT 688 to CKT 348.
6. This test checks for an open in the "Force High" CKT 714.
7. This test determines whether the fault is due to a short from the "Force Low" CKT 688 to the "Sense Low" CKT 752 or a faulty DERM.