Supplemental Inflatable Restraint (SIR)

CIRCUIT DESCRIPTION
At "Turn-ON" the DERM monitors the voltage at the "Sense Low" input, terminal "A6," for 500 milliseconds. The DERM expects the voltage to be within a specific range of "Ignition 1" voltage before the "36 VLR" output is charged. If the "Ignition 1" circuit from the splice to the arming sensor is open, the voltage at the "Sense Low" input, terminal "A6," will be less than a certain percentage of "Ignition 1" voltage and DTC 34 will set.

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

FAILURE CONDITIONS
DTC 34 will set if the voltage at the "Sense Low" input, terminal "A6," is less than a certain percentage of "Ignition 1" voltage for 500 milliseconds and "36 VLR" is less than "Ignition 1" voltage at "Turn-ON."

ACTION TAKEN
DERM turns "ON" the "INFL REST" warning lamp.

CONDITIONS TO CLEAR
To clear DTC 34, the ignition must be "OFF" long enough to assure the "36 VLR" supply voltage has fully discharged (10 minutes). Once the "36 VLR" is discharged, the DERM will again check the failure conditions upon ignition "ON." If the failure conditions are not present (no failure indicated) then, and only then, will current DTC 34 be cleared.

TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This test checks whether the DERM has set the diagnostic trouble code falsely.
2. This test checks whether "Ignition 1" is available at the arming sensor.
3. This test determines whether the malfunction is an open in the arming sensor or an open between the arming sensor and the steering column.