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, harness wiring CKTs 347 and 348 and connector terminal contact in the steering column.

TEST CONDITIONS
Tested once each ignition cycle during the "Steering Column Resistance Test" if: 1) No malfunctions are detected during "Turn-ON"; 2) No malfunctions are detected during "Continuous Monitoring" for 1 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 resistance.

ACTION TAKEN
DERM turns "ON" the "AIR BAG" warning lamp.

CONDITIONS TO CLEAR
Current DTCs 21 and 22 will be cleared each time the ignition switch is turned "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 the integrity of the 430 ohm resistor, the "Sense Low" resistor and associated circuitry in the resistor module.
3. This test checks for a short from CKT 348 or CKT 349 to the "Force Low" circuit.
4. This test checks for an open in the "Force High" circuit.
5. This test checks for a short from the "Force Low" circuit to the "Force High" circuit.
6. This test checks for a short from the "Force Low" circuit to the "Sense Low" circuit.