Supplemental Inflatable Restraint (SIR)

CIRCUIT DESCRIPTION
At "Turn-ON" the DERM monitors the voltage at the "36 VLR" output, terminal "A2," before this circuit begins to charge. If the diode in the arming sensor connected to terminal "B" is shorted, "Ignition 1" voltage will be present at the "36 VLR" output, terminal "A2," as soon as the ignition is turned "ON." If the DERM detects voltage for three ignition cycles in a row, History DTC 33 will be set.

TEST CONDITIONS
Tested once during each ignition cycle at "Turn-ON."

FAILURE CONDITIONS
History DTC 33 will set if the voltage at the "36 VLR" output of the DERM, terminal "A2," is detected within the first 500 milliseconds after the ignition is turned "ON," three ignition cycles in a row.

ACTION TAKEN
DERM stores a History DTC 33.

CONDITIONS TO CLEAR
History DTC 33 will remain as a History diagnostic trouble code until DTCs are cleared with a scan tool.

TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This test checks whether the diagnostic trouble code was set by short ignition cycles.
2. This test checks whether the DERM has set the diagnostic trouble code falsely.
3. This test determines whether the malfunction is a short to B+ on the "36 VLR" circuit or a shorted diode.