Supplemental Inflatable Restraint (SIR)

***This procedure has been updated by TSB 93-17A-9J, October 1992***

CIRCUIT DESCRIPTION
The DERM determines that the arming sensor is closed when a specific percentage of deployment loop voltage or more is present at the "Sense High" input, terminal "A7," and it determines that a discriminating sensor is closed when a specific percentage of deployment loop voltage or less is present at the "Sense Low" input, terminal "A6." If both conditions are detected simultaneously DTC 51 is set.

TEST CONDITIONS
DTC 51 conditions are monitored whenever the DERM is functioning properly.

FAILURE CONDITIONS
Current DTC 51 will set if the DERM senses that both the arming sensor and at least one of the discriminating sensors are closed simultaneously.

ACTION TAKEN
The DERM illuminates the "INFL REST" indicator until Current DTC 51 is cleared. When a History DTC 51 is present, the DERM will not illuminate the "INFL REST" indicator.

CONDITIONS TO CLEAR
Current DTC 51 can be cleared using a TECH 1 "Clear DTCs" command. History DTC 51 will remain in the DERM thereafter.

TEST DESCRIPTION:
Number(s) below refer to circled number(s) on the diagnostic chart.
1. DTC 51, once detected, can be erased as a Current DTC, but will remain as an unerasable History DTC 51.
2. If the inflator module has not deployed, DTC 51 may have been set falsely.
3. If DTC 51 is current with no signs of a frontal crash, the DTC was set falsely.
4. This test checks to see if the DERM set the DTC falsely.
5. This test checks to see if the DTC was set inadvertently during SIR diagnosis.
6. When a frontal crash has occurred, it is necessary to perform the indicated procedures to ensure that the SIR system is fully functional.