B1135

CIRCUIT DESCRIPTION

SIR Schematics:

When you first turn ON the ignition, the inflatable restraint Sensing And Diagnostic Module (SDM) performs tests to diagnose critical malfunctions within itself. Then the SDM proceeds to continuous monitoring. The SDM contains a resistor network connected to 5 volts, ground, and to the SDM front end sensor teed. The 1.0 K ohm resistor in the inflatable restraint front end discriminating sensor parallel to the normally open switch provides a parallel path to ground. This causes a specified percentage of voltage in order to appear at the SDM front end sensor feed input. The SDM monitors this voltage in order to detect shorts to ground or a closed discriminating sensor.

CONDITIONS FOR RUNNING THE DTC
^ The SDM is configured for an inflatable restraint front end discriminating sensor.
^ Ignition 1 Voltage is within the normal operating voltage range.
^ Front end discriminating sensor signal circuit is not shorted to ground.

CONDITIONS FOR SETTING THE DTC
Front end discriminating sensor signal terminal is less than or equal to 0.7 volts for 500 milliseconds.

ACTION TAKEN WHEN THE DTC SETS
The SDM commands ON the AIR BAG warning lamp via Class 2 serial data.

CONDITIONS FOR CLEARING THE DTC
^ The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.
^ A history DTC will clear once 255 malfunction free ignition cycles have occurred.

DIAGNOSTIC AIDS
The following can cause an intermittent condition:
^ A short to ground in the inflatable restraint front end discriminating sensor signal circuit.
^ Cutting or chafing of front end discriminating sensor signal circuit.

Thoroughly inspect the wiring and the connectors. An incomplete inspection of the wiring and the connectors may result in a misdiagnosis, causing a part replacement with the reappearance of the malfunction. If an intermittent malfunction exists, refer to Testing for Intermittent and Poor Connections in Diagrams.

TEST DESCRIPTION

Steps 1-8:

The numbers below refer to the step numbers on the diagnostic table:
4. Tests for a malfunctioning discriminating sensor.
6. Test for a short to ground in discriminating sensor signal circuit.