Part 2 of 2

Test I: DTC 18 Discriminating Sensor Interconnect Open (Part 2 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) on the diagnostic chart.
4. This test determines if the malfunction is in circuit 348E. A circuit 348E malfunction would be a high resistance rather than an open. An open would set different Diagnostic Trouble Codes.
5. This test checks if the malfunction is in the LH Mid-Rail Discriminating Sensor.
6. This test determines if the malfunction is an open in circuit 348C.
7. This test determines whether the malfunction is in circuit 348B. A circuit 348B malfunction would be a high resistance rather than an open. An open would set different Diagnostic Trouble Codes.

DIAGNOSTIC AIDS:
An intermittent condition is likely to be caused by a poor connection to the LH mid-rail discriminating sensor at terminals "A" and "B" or a poor wire to terminal connection in CKTs 348B, 348C or 348E.