Supplemental Inflatable Restraint (SIR)

CIRCUIT DESCRIPTION
Code 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 "IGN 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. Code 24 will set if the arming sensor resistance is too high or open, the discriminating sensor resistance is too low or shorted, the "Force High," "Sense Low" or "Force Low" circuits are shorted to ground or system voltage, the "Sense High" circuit is shorted to ground.

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

FAILURE CONDITIONS
Code 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
DERM turns "On" the "Air Bag" telltale lamp.

CONDITIONS TO CLEAR
Code 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 DESCRIPTIONS
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This test determines whether the fault is in the steering column or the diagnostic circuitry.
2. This test checks the integrity of the "IGN 1" feed to the high side of the deployment loop.
3. This test checks the integrity of the "Sense Low" resistor and associated circuitry in the resistor module.
4. This test checks for an open in the "Sense Low" circuit.
5. This test determines whether the steering column fault is due to the SIR coil or the inflator module.
6. This test checks for an open in Circuit 347.
7. This test checks for a short from Circuit 347 to ground.
8. This test checks for a short from Circuit 348 or Circuit 349 to ground.
9. This test checks for a short from the "Force Low" circuit to ground.
10. This test checks for a short from the "Force High" circuit to ground.
11. This test checks for a short from the "Sense Low" circuit to ground.
12. This test checks for a short from the "Sense High" circuit to ground.
13. This test checks for proper resistance of the passenger side discriminating sensor.
14. This test checks for proper resistance of the driver side discriminating sensor.
15. This test checks for a short from Circuit 347 to B+.
16. This test checks for a short from Circuit 348 or Circuit 349 to B+.
17. This test checks for a short from the "Force Low" circuit to B+.
18. This test checks for a short from the "Force High" circuit to B+.
19. This test checks for a short from the "Sense Low" circuit to B+.
20. This test checks for proper resistance of the passenger side discriminating sensor.
21. This test checks for proper resistance of the driver side discriminating sensor.