DTC 21 and 22

Electrical Diagram:

CIRCUIT DESCRIPTION
The DERM injects a current of 75 milliamps 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 CKT 347 and 348 and connector terminal contact in the steering column.

TEST CONDITION(S)
Tested once each ignition cycle during the "Steering Column Resistance Test" If: 1) No faults are detected during "Turn-ON"; 2) No faults are detected during "continuous monitoring" or 1 second; 3) No crank signal present; 4) "Ignition 1 voltage is present.

FAILURE CONDITION(S)
Codes 21 and 22 will set if the voltage at the "Sense Low" input, terminal "A6" is less than S volts during the steering column resistance test. This will occur when the "Force High" output, terminal "A4," is open and results in an undetermined steering column resistance.

ACTION TAKEN
DERM turns "ON" the "INFL REST" warning lamp.

CONDITIONS TO CLEAR
Current Codes 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 2490 ohm resistors 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 "Sense Low" circuit.