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
DERM turns "ON" the "INFL REST" warning lamp until current DTC 51 is cleared. History DTC 51 will not turn "ON" the warning lamp.

CONDITIONS TO CLEAR
Current DTC 51 can only be cleared using a scan tool "Clear Codes" command. History DTC 51 wilt 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 diagnostic trouble code but will remain as an unerasable history diagnostic trouble code.
2. If the inflator module has not deployed DTC 51 may have set falsely.
3. If DTC 51 is current with no signs of frontal impact the diagnostic trouble code has set falsely.
4. This test checks for a DERM malfunction setting the diagnostic trouble code falsely.
5. This test determines whether the diagnostic trouble code was set inadvertently during diagnosis.
6. When an accident has occurred it is necessary to perform the indicated procedures to ensure the SIR system is fully functional.