DTC 81

Test AH: DTC 81 Driver Ignition Diode Open:

Supplemental Inflatable Restraint (SIR):

OPERATION:
During the "Turn-ON" tests. performed at the beginning of each ignition cycle, the DERM delays the charging of the "Driver 36 VLR" and "Passenger 36 VLR" power supplies. While the delay is active the DERM measures the voltage at the "Driver 36 VLR" terminal "A4", "Passenger 36 VLR" terminal "A3", "Driver Source Sense" terminal "A5". and "Passenger Source Sense" terminal "A6." When the voltage measured at the two "36 VLR" power supplies indicates they are in a discharged state, the voltage measured at "Passenger Source Sense" is within a specified range of "Ignition 1" voltage and the voltage measured at "Driver Source Sense" is a specified amount below "Ignition 1" voltage DTC 81 is set.

Test Conditions: Tested once each ignition cycle during the "Turn-ON" tests while the "36 VLR Delay" is active.

Failure Condition: DTC 81 will set when, with both "36 VLR" power supplies in a discharged state, the DERM detects "Ignition 1" voltage at "Passenger Source Sense" terminal "A6" while simultaneously the DERM does not detect "Ignition 1" voltage at "Driver Source Sense" terminal "A5."

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

Conditions to Clear: DTC 81 will clear when, with both "36 VLR" power supplies in a discharged state, the voltages measured at "Driver Source Sense" terminal "A5" and "Passenger Source Sense" terminal "A6" are simultaneously within a specified range of "Ignition 1" voltage. When neither the failure nor clear conditions are met, the state of the Diagnostic Trouble Code from the previous ignition cycle is used.

POSSIBLE CAUSES:
Test Description: Number(S) below refer to circled number(S) on the diagnostic chart.
1. This test checks for a short from the "Driver Source Sense" circuit to the "Passenger 36 VLR" circuit
2. This test checks for a short from the "Driver Source Sense" circuit to the "Driver 36 VLR" circuit.
3. This test determines if the malfunction is due to an open within the Dual Pole Arming Sensor.

DIAGNOSTIC AIDS:
An intermittent condition is likely to be caused by a short between CKT 1400 and CKT 236, a short between CKT 1400 and CKT 1401, or an open inside the dual pole arming sensor. The test for this diagnostic trouble code is only run while the "INFLATABLE RESTRAINT" warming lamp is performing the bulb check. When a scan tool "Clear Codes" command is issued and the malfunction is still present, the DTC will not reappear until the ignition switch is fumed "OFF" for at least 2 minutes with the entire SIR system connected and then the ignition switch turned "ON."