Supplemental Inflatable Restraint (SIR)

CIRCUIT DESCRIPTION
DTC 24 is set when the voltage at the "Sense Low" input, terminal "A6," is within a specific range of "36 VLR" output voltage for 500 milliseconds during the "Continuous Monitoring Tests" performed by the DERM. The "Continuous Monitoring Tests" are performed by the DERM after the initial "Turn-ON Tests" are completed and 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 24 will set if the arming sensor resistance is too high or open, a discriminating sensor is shorted or resistance is too low, the "Force High," "Sense Low" or "Force Low" circuits are shorted to ground or system voltage, or the "Sense High" circuit is shorted to ground.

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

FAILURE CONDITIONS
DTC 24 will set if the voltage at the "Sense Low" input, terminal "A6," is within a specific range of "36 VLR" output voltage for 500 milliseconds.

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

CONDITIONS TO CLEAR
DTC 24 will clear if the voltage at the "Sense Low" input, terminal "A6," is within a specific range of "36 VLR" output voltage for 500 milliseconds.

TEST DESCRIPTION:
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This test determines whether the fault is in the steering column circuitry or the diagnostic circuitry.
2. This test checks the integrity of the "Ignition 1" feed to the high side of the deployment loop.
3. This test checks the integrity of the "Sense Low" 2490 ohm resistor and associated circuitry in the resistor module.
4. This test determines whether the steering column fault is due to a faulty SIR coil assembly or a faulty inflator module.
5. This test checks for an open in the "Sense Low" CKT 752.
6. This test checks for a short to ground in CKT 347.
7. This test checks for a short to ground in CKT 341.
8. This test checks for a short to ground in CKT 340.
9. This test checks for a short to ground in CKT 349.
10. This test checks for a short to ground in CKT 348.
11. This test checks for a short to ground in the "Force High" CKT 714.
12. This test checks for a short to ground in the "Sense Low" CKT 752.
13. This test checks for a short to ground in the "Sense High" CKT 753.
14. This test checks for a short to ground in the "Force Low" CKT 688.
15. This test checks for a faulty forward discriminating sensor.
16. This test determines whether the fault is due to a faulty passenger compartment discriminating sensor or a faulty DERM.
17. This test checks for a short to B+ in CKT 347.
18. This test checks for a short to B+ in CKT 341.
19. This test checks for a short to B+ in CKT 340.
20. This test checks for a short to B+ in CKT 349.
21. This test checks for a short to B+ in CKT 348.
22. This test checks for a short to B+ in the "Force High" CKT 714.
23. This test checks for a short to B+ in the "Sense Low" CKT 752.
24. This test checks for a short to B+ in the "Force Low" CKT 688.
25. This test checks for a faulty forward discriminating sensor.
26. This test checks for a faulty passenger compartment discriminating sensor.
27. This test determines whether the fault is due to a faulty arming sensor or a faulty DERM.