B0090

Schematic:

CIRCUIT DESCRIPTION
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 deployment loop is not shorted to voltage.

CONDITIONS FOR SETTING THE DTC
^ The voltage detected at passenger frontal SIR enable terminal and passenger frontal SIR disable terminal are less than 1.0 Volt when the AIR BAG ON lamp is commanded ON
^ The voltage detected at passenger frontal SIR enable terminal and passenger frontal SIR disable terminal are greater than 4.0 Volts when the AIR BAG ON lamp is commanded OFF.
^ The voltage detected at passenger frontal SIR enable terminal and passenger frontal SIR disable terminal are greater than 1.0 Volt when the AIR BAG OFF lamp is commanded ON.

ACTION TAKEN WHEN THE DTC SETS
^ The inflatable restraint IP module switch is defaulted to the disabled state.
^ The SDM commands ON the AIR BAG warning lamp via Class 2 serial data.
^ The SDM attempts to illuminate the inflatable restraint IP module switch AIR BAG OFF lamp.

CONDITIONS FOR CLEARING THE DTC
^ The inflatable restraint IP module switch AIR BAG lamp is OFF, and the voltage at passenger frontal SIR enable terminal and passenger frontal SIR disable terminal are in opposite states for 300 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 the passenger frontal SIR disable circuits.
^ Refer to Testing for Intermittent and Poor Connections in Diagrams.

TEST DESCRIPTION

Test Step 1 - Step 5:

Test Step 6 - Step 14:

Test Step 15 - Step 22:

Test Step 23 - Step 33:

The numbers below refer to the step numbers on the diagnostic table:
2. Test determines if the AIR BAG ON lamp illuminates when the inflatable restraint IP module switch is in the ON position.
3. Tests for a poor connection at the inflatable restraint IP module switch harness connector.
6. Test determines whether the malfunction is in the inflatable restraint IP module switch ground circuit.
8. Test determines whether the malfunction is in the power feed circuit between the fuse block and the inflatable restraint IP module switch.
11. Tests for proper contact or corrosion of the inflatable restraint sensing and diagnostic module (SDM) harness connector.
12. Tests for an open or high resistance in the passenger SIR enable circuit.
14. Tests for a short to ground in the passenger SIR enable circuit.
16. Tests for a short to voltage in the passenger SIR disable circuit.
18. Tests for a short between the passenger SIR enable and disable circuits.
24. Tests for a short to voltage in the passenger SIR disable circuit.
26. Tests for a short to voltage in the passenger SIR enable circuit.
28. Tests for an open or high resistance in the passenger SIR disable circuit.
30. Tests for a short to ground in the passenger SIR disable circuit.