R021

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

During the 'Initiator Circuit Resistance' tests, the DERM grounds the 'PASSENGER'S SENSE LOW', terminal 'B7', and turns 'ON' the Driver's Current Source at 'DRIVER'S SENSE HIGH', terminal 'B9', and injects a 150 milliamp current for 50 milliseconds into the circuit. During this test the DERM monitors the voltage at 'DRIVER'S SENSE LOW' and 'DRIVER'S SENSE HIGH'. The voltage difference between 'DRIVER'S SENSE HIGH' and 'DRIVER'S SENSE LOW' is used to calculate the resistance of the driver's initiator loop. When the resistance is above a given value, Code R021 is set.


TEST CONDITION(S)

Tested once, each ignition cycle during 'Initiator Circuit Resistance' tests 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 at DERM;

4. 'Ignition 1' voltage is greater than 7.25 volts at DERM.


FAILURE CONDITION(S)

Combined resistance of the Driver's Inflator Module, SIR Coil, harness wiring and connector terminal contacts is greater than a specified value.

CONDITIONS TO CLEAR

Current Code R021 clears each time the ignition switch is turned 'OFF'.


ACTION TAKEN

1. DERM turns on the 'INFLATABLE RESTRAINT' indicator.

2. 'SERVICE SUPPLEMENTAL INFLATABLE RESTRAINT' message is displayed on DIC.

3. Code R021 remains set for the entire ignition cycle.

4. Current Code R021 clears each time the ignition switch is cycled from 'ON' to 'OFF'.


NOTES ON FAULT TREE

1. Checks if fault is in the steering column. The SIR Load Tool J 38715 simulates the proper resistance of steering column wiring and components.

2. Checks for an open or high resistance in the 'DRIVER'S SENSE HIGH' circuit between the DERM and the steering column connector or faulty DERM.

3. Determines if fault is in Driver's Inflator Module or in the SIR Coil. The SIR Load Tool J 38715 simulates the proper resistance of the Driver's Inflator Module.