B1022

Circuit Description

When you first turn the ignition switch to the RUN position, the Inflatable Restraint Sensing and Diagnostic Module (SDM) performs tests in order to diagnose critical malfunctions within the module. Next the SDM measures the ignition positive voltage and the deployment loop voltages in order to ensure that the voltages are within the respective normal voltage ranges. The SDM proceeds with the resistance measurement test. During 1 portion of the resistance measurement test, the SDM performs the following functions:

^ Grounds the DRIVER LOW terminal 3 through an internal current sink.

^ Connects the DRIVER HIGH terminal 2 to an internal constant current source. This current produces proportional voltage drops in the deployment loop.

^ Measures the voltage difference between the DRIVER HIGH and the DRIVER LOW.

^ Calculates the resistance of the driver deployment loop using the measured voltage.

Conditions for Setting the DTC

^ The driver and passenger deployment loops are not open.

^ The driver and passenger deployment loops are not shorted to voltage.

^ The driver deployment loop is not shorted to ground.

^ The driver deployment loop resistance is less than 1.7 ohms. The driver deployment loop consists of the following components:

- An Inflatable Restraint Steering Wheel Module

- An Inflatable Restraint Steering Wheel Module Coil

- Harness wiring of circuit 347

- Harness wiring of circuit 348

- Connector terminal contact

The resistance measurement test inspects for this malfunction. This test only occurs once each ignition cycle when the ignition positive voltage is within the normal operating voltage range.

Action Taken When the DTC Sets

^ The SDM sets a diagnostic trouble code.

^ The SDM turns ON the AIR BAG Warning Indicator.

Conditions for Clearing the MIL/DTC

^ Current DTC

The resistance of the driver deployment loop is more than 1.7 ohms and the ignition switch is cycled.

^ History DTC

- You issue a scan tool CLEAR CODES command.

- 250 malfunction free ignition cycles have occurred.

When you issue a scan tool CLEAR CODES command and the malfunction is still present, the DTC will not reappear until the next ignition cycle.

Diagnostic Aids

The following conditions may cause an intermittent condition:

^ A short circuit between circuit 347 and circuit 348

^ A short circuit between circuit 347 and circuit 1403

^ A short circuit between circuit 347 and circuit 1404

^ A malfunctioning shorting bar on the Inflatable Restraint Steering Wheel Module connector

^ A malfunctioning shorting bar on the Inflatable Restraint Steering Wheel Module Coil steering column connector

The diagnostic table directs the technician in order to note the entry value of the driver resistance. Comparing the value of driver resistance over multiple ignition cycles may be helpful in determining if an intermittent condition exists.

When measurements are requested in this table, use J 39200 Digital Multimeter with the correct terminal adapter from J 35616-A Connector Test Adapter kit. When a check for proper connection is requested, refer to Intermittents and Poor Connections. When a wire, connector or terminal repair is requested, use J 38125-B Terminal Repair kit and refer to Wiring Repair.

Test Description

The numbers below refer to the step numbers on the diagnostic table:

2. This test determines the deployment loop resistance measured by the Inflatable Restraint Sensing and Diagnostic Module (SDM).

6. This test isolates the malfunction to one side of the Inflatable Restraint Steering Wheel Module Coil yellow 2-way connector.

7. This test determines whether the malfunction is due to the Inflatable Restraint Steering Wheel Module or the module coil.

10. This test checks for a short from circuit 347 to circuit 348.

12. This test checks for a short from circuit 347 to circuit 1404.