R018

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

During the 'Initiator Circuit Resistance' tests, the DERM first grounds the 'DRIVER'S SENSE LOW', terminal '138', for 50 milliseconds and then monitors the voltage at both the 'DRIVER'S SENSE LOW' and 'PASSENGER'S SENSE LOW', terminals '138' and '137'. The DERM then simultaneously opens the 'DRIVER'S SENSE LOW', terminal '138', and grounds the 'PASSENGER'S SENSE LOW', terminal '137', for 50 milliseconds. The DERM again monitors the voltage at both the 'DRIVER'S SENSE LOW' and 'PASSENGER'S SENSE LOW', terminals '138' and 'B?'. Code R018 sets if the 'DRIVER'S SENSE LOW' or 'PASSENGER'S SENSE LOW' voltage, but not both, 'SENSE LOW' voltages is greater than 3 volts during 'Initiator Circuit Resistance' test. Code R018 is also tested for approximately 100 milliseconds every 10 minutes.


TEST CONDITION(S)

Tested each ignition cycle during the 'Initiator Circuit Resistance' tests and '10 Minute Loop' 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 at DERM;

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

FAILURE CONDITION(S)

When one, but not both, 'SENSE LOW' voltage is greater than 3 volts.

ACTION TAKEN

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

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

3. Code R018 remains current until both the 'DRIVER'S SENSE LOW' and 'PASSENGER'S SENSE LOW' voltages are less than 3 volts during both the 'Initiator Circuit Resistance' tests or '10 Minute Loop' test.

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.