B0091

CIRCUIT DESCRIPTION

SIR Schematics:

When you first turn the ignition switch to the RUN position, the Inflatable Restraint Sensing And Diagnostic Module (SDM) performs tests to diagnose critical malfunctions within itself. The SDM monitors the voltage levels at the passenger frontal SIR enable and disable terminals of the SDM to determine the position of the inflatable restraint IP module switch. The SDM then performs the following continuous diagnostic tests on the deployment loops:
^ Deployment loop voltage out of range test
^ Deployment loop resistance measurement test
If the voltage out of range test detects a short to voltage condition, the resistance measurement test for that deployment loop will not be performed.

CONDITIONS FOR RUNNING THE DTC
^ Ignition 1 voltage is within the normal operating voltage range.
^ Passenger frontal SIR enable circuit is not shorted to voltage.
^ Passenger frontal SIR disable circuit is not shorted to voltage.

CONDITIONS FOR SETTING THE DTC
The voltage at passenger SIR enable is low with the passenger AIR BAG lamp ON and the voltage at passenger SIR disable is high.

ACTION TAKEN WHEN THE DTC SETS
^ The inflatable restraint IP module switch is defaulted to a calibrated state.
^ The SDM commands ON the AIR BAG warning lamp via Class 2 serial data.
^ The SDM toggles the inflatable restraint IP module switch AIR BAG lamp ON and OFF every 5 seconds.

CONDITIONS FOR CLEARING THE DTC
^ The inflatable restraint IP module switch AIR BAG lamp is ON and the voltage at passenger frontal SIR enable and passenger frontal SIR disable terminals is low for 500 milliseconds.
^ You issue a scan tool CLEAR CODES command.
^ A history DTC will clear once 255 malfunction free ignition cycles have occurred.

When the SDM detects that no DTCs are present, the SDM commands the AIR BAG warning lamp OFF.

DIAGNOSTIC AIDS
The following can cause an intermittent condition:

A short between the passenger frontal SIR enable and passenger frontal SIR disable circuits.

Refer to Testing for Intermittent and Poor Connections in Diagrams.

TEST DESCRIPTION

Steps 1-10:

The number(s) below refer to the step number(s) on the diagnostic table.
2. Observes the state of the inflatable restraint IP module Switch, normal state being ON.
3. Tests for a malfunctioning inflatable restraint IP module switch.
4. Tests for a malfunctioning Inflatable Restraint Sensing And Diagnostic Module (SDM).
5. Tests for a short in the signal circuits between the inflatable restraint IP module switch and the Inflatable Restraint Sensing And Diagnostic Module (SDM).
8. This step replaces the Inflatable Restraint Sensing And Diagnostic Module (SDM).