Supplemental Inflatable Restraint (SIR)

Diagnostic Chart:

Wiring Diagram:

CIRCUIT DESCRIPTION

When the ignition switch is turned to "RUN," the SDM will perform tests to diagnose critical malfunctions within itself. Upon passing these tests, "Ignition 1," 23 VLR, and deployment loop voltages are measured to ensure they are within their respective normal voltage ranges. The SDM then proceeds to "Continuous Monitoring." The SDM contains a resistor network connected to "Ignition 1," ground, and to SDM sensor signal terminal "9." The 1.0 Kohms resistor in the front end discriminating sensor, parallel to the normally open switch, provides a parallel path to ground. This causes a specified percentage of voltage to appear at the SDM sensor signal input. This voltage is monitored to detect shorts to voltage or an open discriminating sensor circuit.


DTC WILL SET WHEN:

"Ignition 1" is within the normal operating voltage range and the SDM is configured for a front end discriminating sensor. Once these conditions are met and the front end discriminating sensor input is above a specified value, DTC 36 will set.

ACTION TAKEN:

SDM turns "ON" the "AIR BAG" indicator and sets a diagnostic trouble code.


DTC WILL CLEAR WHEN

The voltage measured at the front end discriminating sensor input is below a specified value for 500 milliseconds.


DTC CHART TEST DESCRIPTION

Number(s) below refer to circled number(s) on the diagnostic chart.

1. This test checks for a malfunctioning discriminating sensor.

2. This test checks for an open in CKT 1851.

3. This test checks for an open in CKT 1834.


DIAGNOSTIC AIDS

An intermittent condition is likely to be caused by a broken or chafed wire in the discriminating sensor circuit. Inspect CKTs 1834 and 1851 carefully for cutting or chafing.