Part 1 of 2

Test I: DTC 18 Discriminating Sensor Interconnect Open (Part 1 Of 2):

Supplemental Inflatable Restraint (SIR):

OPERATION:
During the "Initiator Assembly Resistance Test" the DERM grounds the "Driver Side Low" terminal "B8" and measures the voltage at "Driver Side Low" and "Passenger Side Low." The DERM then grounds "Passenger Side Low" terminal "B7" and again measures the voltage at "Driver Side Low" and "Passenger Side Low." For a properly operating circuit the voltage measurements during each of these tests will be below a specified value. When the voltage measured at either "Driver Side Low" or "Passenger Side Low", but not both, is above a specified value during either test DTC 18 is set.

Test Conditions: Tested during the "Initiator Assembly Resistance Test" and the "10 Minute Loop Test" when: 1) No "higher priority faults" are detected during "Turn-ON", 2) No "higher priority faults" are detected during "Continuous Monitoring" for 1 second, 3) No "CRANK" signal present, 4) "Ignition 1" voltage is above a specified value.

Failure Conditions: DTC 18 will set when the voltage measured at either "Driver Side Low" or "Passenger Side Low", but not both, is above a specified value while the DERM attempts to ground either of these terminals.

Action Taken: DERM turns "ON" the "INFLATABLE RESTRAINT" warning lamp and sets a Diagnostic Trouble Code.

Conditions to Clear: DTC 18 will clear when the voltages measured at both "Driver Side Low" and "Passenger Side Low" are below specified value while the DERM grounds each of the terminals.

POSSIBLE CAUSES:
Test Description: Number(S) below refer to circled number(S) an the diagnostic chart.
1. This test checks whether the interconnect malfunction is due to a malfunctioning Forward Discriminating Sensor.
2. This test determines if the malfunction is in circuit 1404B. A circuit 1404B malfunction would be a high resistance rather than an open. An open would set different Diagnostic Trouble Codes.
3. This test determines whether the malfunction is in the RH Mid-Rail Discriminating Sensor.

DIAGNOSTIC AIDS:
An intermittent condition is likely to be caused by a poor connection to the forward discriminating sensor terminals "A" and "B," the RH mid-rail discriminating sensor terminals "A" and "B," or poor wire to terminal connection in CKT 1404B. When a scan tool "Clear Codes" command is issued and the malfunction is still present, the DTC will not reappear for 10 minutes or until the next ignition cycle. For additional information, refer to Diagnostic Aids for Test 1 (part 2 of 2). Part 2 of 2