Supplemental Inflatable Restraint (SIR)

Electrical Diagram:

CIRCUIT DESCRIPTION
The voltage at the "Sense Low" input, terminal "A6," is between 41% and 61% of "36VLR" output voltage when "36VLR" output of the DERM is functional. Should the circuit open between the "36vLR" output and the arming sensor, "Ignition 1" voltage will be supplying the deployment loop. The voltage at the "Sense Low" input terminal "A6" will decrease due to the lower supply voltage and Code 31 will set after 700 milliseconds (if Code 42 is not set). Code 31 indicates an open in the wiring between the "36VLR" output of the DERM and the arming sensor.

TEST CONDITION(S)
Test every 100 milliseconds during "Continuous Monitoring".

FAILURE CONDITION(S)
Code 31 will set if the voltage at the "Sense Low" input, terminal A6," is between 28% and 59% of "ignition 1" voltage for 700 milliseconds and Code 42 is not set.

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

CONDITIONS TO CLEAR
Current Code 31 will clear if the voltage at the "Sense Low" input, terminal "A6," is between 41% and 61% of "36VLR" output voltage for 500 milliseconds.

TEST DESCRIPTION
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This test checks for "36VLR" at the arming sensor terminal "B".
2. This test checks for an improper connection at the arming sensor or a fault in the arming sensor connector.
3. This test checks for "36VLR" at the arming sensor terminal "C." Since it is known that "36VLR" is available at terminal "B," the absence of "36VLR" at terminal "C" indicates a faulty sensor or wiring connection. Note that the voltage at "C" will be 0.7 volt less than the voltage measured at terminal "B" due to the internal diode "B" voltage drop.
4. This test checks for an open in CKT 236.
5. This test checks for a short between CKTs 688 and 800.
6. This test determines if fault is in deployment loop or DERM. If voltage at "Sense Low" falls between 41% and 61% of voltage at "36VLR" then the fault is not in the deployment loop components or wiring.
7. This test indirectly checks the integrity of the arming sensor diode "B," diagnostic resistor and pigtail wiring. If the discriminating sensors and associated wiring fall within acceptable range, the arming sensor is assumed faulty.
8. This test determines if the condition causing a low resistance value is attributed to the FWD sensor or associated wiring.
9. This test determines if the condition causing low resistance is in the FWD sensor or wiring.
10. This test determines if the condition causing a low resistance value is attributed to the LH sensor or associated wiring.
11. This test determines if the condition causing a low resistance value is attributed to the RH sensor or associated wiring.
12. This test determines if the condition causing low resistance is in the LH sensor or wiring.