Supplemental Inflatable Restraint (SIR)

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 Code 51 is set.

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

FAILURE CONDITIONS
Cycle Code 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 "Air Bag" telltale lamp until Cycle Code 51 is cleared. History Code 51 will not turn "On" the "Air Bag" telltale lamp.

CONDITIONS TO CLEAR
Cycle Code 51 can be cleared using a PDT "Clear Codes" command. History Code 51 will remain in the DERM thereafter.

NOTE: History code Si can be cleared for the current ignition "ON" cycle, but will reappear at the next ignition "ON" cycle.

TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. Code 51, once detected, can be erased as a Cycle Code but will remain as an un-erasable history code.
2. If the inflator module has not deployed, Code 51 may have set falsely.
3. If Code 51 is current with no signs of frontal impact, the code has set falsely.
4. This test checks for a DERM fault, setting the code falsely.
5. This test determines whether the 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.