Chart 1

Code 22 (Chart 1):

DERM Circuit Detail:

Description:

The DERM injects a current of 75 milliamperes through the steering column from the Force Hi output (terminal A4)to the Force Low input (terminal A10). By monitoring the voltage at the Sense Hi input (terminal A7) and the Sense Low input (terminal A6) the DERM calculates the combined resistance of the Inflator Module, SIR Coil and connector terminal contact in the steering column. Code 22 will set if:
^ The steering column resistance is less than a specified value.
^ The 430 ohm resistor in the Resistor Module is shorted.
^ The resistance of the 100 ohm resistor in the Resistor Module is too high.
^ The high side of the deployment loop is shorted to the low side of the deployment loop.

TEST CONDITIONS:

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" for 1 second.
3. No Crank signal present.

FAILURE CONDITIONS:

Code 22 will set if the combined resistance of the Inflator Module, SIR Coil, harness wiring and connector terminal contact in the steering column is less than a specified value.

CONDITIONS TO CLEAR:

Current Code 22 will be cleared each time the Ignition Switch is turned OFF.

ACTION TAKEN:

DERM turns on the "INFLATABLE RESTRAINT" indicator lamp.

NOTES ON FAULT TREE:

1. Checks if fault is in steering column. The SIR Load Tester J37808 simulates the resistance of good steering column wiring and components.

2. Checks if fault is in Inflator Module or in the SIR Coil. The SIR Load Tester J37808 simulates the resistance of a good Inflator Module.

3. Checks if fault is on deployment loop side or DERM side of resistor module.

4. Checks if the 430 ohm resistor in the Resistor Module is shorted.

5. Checks if fault is in Dual Sensor or in wiring harness.