Supplemental Inflatable Restraint (SIR)

CIRCUIT DESCRIPTION
DTC 23 is set when the voltage at the "Sense Low" input, terminal "AS," is greater than a specific percentage of "36 VLR" output voltage for 500 milliseconds during the "Continuous Monitoring Tests" performed by the DERM. The "Continuous Monitoring Tests" are performed every 100 milliseconds while "Ignition 1" voltage is present at the DERM. The "Continuous Monitoring Tests" check the continuity of the deployment loop from the "36 VLR" output of the DERM through the arming sensor, inflator module and the discriminating sensors to ground. DTC 23 indicates a shorted arming sensor or a short to the "36 VLR" CKT 236.

TEST CONDITIONS
Tested every 100 milliseconds during the "Continuous Monitoring Tests."

FAILURE CONDITIONS
DTC 23 will set if the voltage at the "Sense Low" input, terminal "AS," is greater than a specific percentage of "36 VLR" output voltage for 500 milliseconds.

ACTION TAKEN
The DERM illuminates the "INFL REST" indicator.

CONDITIONS TO CLEAR
Current DTC 23 will clear when the voltage at the "Sense Low" input, terminal "AS," is within a specific range of "36 VLR" output voltage for 500 milliseconds (five "Continuous Monitoring Tests" cycles) after it has been set.

TEST DESCRIPTION:
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This test checks the integrity of the high side of the deployment loop.
2. This test checks for a short from the "36 VLR" CKT 236 to CKT 341.
3. This test checks for a short from the "36 VLR" CKT 236 to CKT 340.
4. This test checks for a short from the "36 VLR" CKT 236 to CKT 349.
5. This test checks for a short from the "36 VLR" CKT 236 to CKT 348.
6. This test checks the integrity of the "Sense Low" 2490 ohm resistor and associated circuitry in the resistor module.
7. This test determines whether the fault is due to a short from the "36 VLR" CKT 236 to CKT 347 or a faulty arming sensor.
8. This test checks for a short from the "36 VLR" CKT 236 to the "Force High" CKT 714.
9. This test checks for a short from the "35 VLR" CKT 236 to the "Sense Low" CKT 752.
10. This test determines whether the fault is due to a short from the "36 VLR" CKT 236 to the "Force Low" CKT 688 or a faulty DERM.