B0026

CIRCUIT DESCRIPTION

SIR Schematics:

When the ignition is first turned ON, the Inflatable Restraint Sensing And Diagnostic Module (SDM) performs tests to diagnose critical malfunctions within itself. 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.

CONDITIONS FOR SETTING THE DTC
^ The SDM detects the driver frontal deployment loop resistance is greater than 4.8 Ohms for 500 milliseconds.
^ The SDM detects the voltage at driver frontal high is less than 2.4 volts and driver frontal high to low side resistance is 6 Ohms or greater for 500 milliseconds.

ACTION TAKEN WHEN THE DTC SETS
^ The SDM commands ON the AIR BAG indicator via Class 2 serial data.
^ The SDM also sets this DTC as current after an accident. The SDM will write the status of this DTC to the "crash log" area of the EEPROM for retrieval.

CONDITIONS FOR CLEARING THE DTC
^ You issue a scan tool CLEAR DTCs command.
^ A history DTC will clear once 255 malfunctions free ignition cycles have occurred.

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

DIAGNOSTIC AIDS
The following can cause an intermittent condition:
^ A short between the driver frontal high and the driver frontal low circuits.
^ A malfunctioning shorting bar on the inflatable restraint steering wheel module 2-way connector.
^ A malfunctioning shorting bar on the inflatable restraint steering wheel module coil 2-way connector.

Refer to Testing for Intermittent and Poor Connections in Diagrams.

TEST DESCRIPTION

Steps 1-2:

Steps 3-8:

Steps 9-16:

The number(s) below refer to the step number(s) on the diagnostic table.
2. This step inspects the driver inflator module in-line connector below the inflatable restraint steering wheel module coil.
6. Tests for the proper operation of inflatable restraint steering wheel module coil and/or inflatable restraint steering wheel module.
9. This step checks to see if the SDM harness connector is OK.
11. Tests for an open or a high resistance in the driver frontal high circuit.
13. Tests for an open or a high resistance in the driver frontal low circuit or if there is a malfunctioning SDM.