Part 2 of 3

Test N: DTC 24 Initiator Circuit Voltage Low (Part 2 Of 3):

Supplemental Inflatable Restraint (SIR):

OPERATION:
During normal, non-deployment operation of the SIR system, a small amount of current flows through both the Driver and Passenger Deployment Loops. The diagnostic resistors within the Dual Pole Arming Sensor and the Discriminating Sensors along with the resistance of the inflator modules cause voltage drops within the Deployment Loops. The DERM monitors the voltages at "Driver Side Low" terminal "B8" and "Passenger Side Low" terminal "B7" to detect shorts or opens within the deployment loops. When the measured voltage at terminals "B8" or "B7" is below a specified percentage of its respective "36 VLR" power supply voltage for 500 milliseconds DTC 24 is set.

Test Conditions: Tested every 100 milliseconds during the "Continuous Monitoring" test.

Failure Conditions: DTC 24 will set when the voltage measured at "Driver Side Low" terminal "B8" is below a specified percentage of "Driver 36 VLR" or when the voltage measured at "Passenger Side Low" terminal "B7 is below a specified percentage of "Passenger 36 VLR" for 500 milliseconds.

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

Conditions to Clear: DTC 24 will clear when the voltage measured at "Driver Side Low" terminal "B8" is within a specified percentage of "Driver 36 VLR" and the voltage measured at "Passenger Side Low" terminal "B7" is within a specified percentage of "Passenger 36 VLR" for 500 milliseconds.

POSSIBLE CAUSES:
Test Description: Number(S) below refer to circled number(S) on the diagnostic chart.
3. This test checks for a partial short across the Diagnostic Resistor in the LH Mid-Rail Discriminating Sensor.
4. This test checks for a partial short across the Diagnostic Resistor in the RH Mid-Rail Discriminating Sensor.
5. This test checks for a short from the low side of the Driver Deployment Loop to ground.
6. This test checks for a short from the high side of the Driver Deployment Loop to ground.
7. This test checks for a short from the low side of the Passenger Deployment Loop to ground.

DIAGNOSTIC AIDS:
Refer to Diagnostic Aids for Test N (part 1 of 3). Part 1 of 3