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 SDM. Upon passing these test the following circuits are measured in order to ensure that they are within their respective normal voltage ranges:
^ IGNITION 1
^ Deployment loop voltages
Then the SDM proceeds with the RESISTANCE MEASUREMENT test. During one portion of the RESISTANCE MEASUREMENT test, the SDM performs the following steps:
^ Grounds the DRIVER SIDE LOW terminal 3 through an internal current sink
^ Connects the DRIVER SIDE HIGH terminal 2 to an internal constant current source
This current produces proportional voltage drops in the deployment loop.
^ Measures the voltage difference between DRIVER SIDE HIGH and DRIVER SIDE 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:
- The Inflatable Restraint Steering Wheel Module
- The Inflatable Restraint Steering Wheel Module Coil
- The harness wiring of circuit 347
- The harness wiring of circuit 348
- The connector terminal contact
The RESISTANCE MEASUREMENT test inspects for this malfunction. This test only occurs once each ignition cycle when IGNITION 1 is within the normal operating voltage range.

Action Taken When the DTC Sets
^ The SDM sets a diagnostic trouble code.
^ The SDM turns the AIR BAG warning lamp to the ON position.

Conditions for Clearing the DTC
^ Current DTC
- The resistance of the driver deployment loop is more than 1.7 ohms.
- The ignition switch is cycled.
^ History DTC
- You issue a scan tool CLEAR CODES command.
- After 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 items can 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 to note the entry value of DRIVER RESISTANCE. Comparing the value of DRIVER RESISTANCE over multiple ignition cycles can be helpful in determining if an intermittent condition exists.
When measurements are requested in this table, use the J 39200 DMM with the correct terminal adapter from the J 35616-A Connector Test Adapter Kit.

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 inspects for a short from circuit 347 to circuit 348.
12. This test inspects for a short from circuit 347 to circuit 1404.