R028

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 'Drivers Current Source' at 'DRIVER'S SENSE HIGH', terminal 'B9' and injects a 150 milliamp current for 50 milliseconds into the circuit. The DERM then grounds the 'DRIVER'S SENSE LOW', terminal 'B8', and turns 'ON' the 'Passenger's Current Source' at 'PASSENGER'S SENSE HIGH', terminal A7', and injects a 150 milliamp current for 50 milliseconds into the circuit. During each of these tests, the DERM monitors the voltage at 'DRIVER'S SENSE LOW', 'DRIVER'S SENSE HIGH', 'PASSENGER'S SENSE LOW' and 'PASSENGER'S SENSE HIGH'. The voltage difference between 'DRIVER'S SENSE HIGH and LOW', and 'PASSENGER'S SENSE HIGH and LOW' is used to calculate the resistance of the Driver's and Passenger's initiator loops. When either loops voltage difference is outside a given range, Code R028 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 is greater than 7.25 volts at DERM.

FAILURE CONDITION(S)

1. 'DRIVER'S SENSE LOW' or 'PASSENGER'S SENSE LOW' voltage is below a specified value while its respective initiator resistance is in range;

OR

2. 'DRIVER'S SENSE LOW' or 'PASSENGER'S SENSE LOW' voltage is above a specified value.

ACTION TAKEN

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

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

3. Current Code R028 clears each time the ignition switch is cycled from 'ON' to 'OFF'.

NOTES ON FAULT TREE

1. Checking if increased resistance in the system is due to a fault in the RH Discriminating Sensor.

2. Checking for increased resistance in CKT 1404.

3. Checking for increased resistance in CKT 348 or a faulty DERM.