B1022

Diagnostic Chart:

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. Next the SDM measures IGNITION POSITIVE VOLTAGE and the deployment loop voltages to make sure they are within their respective normal voltage ranges. Then the SDM proceeds with the RESISTANCE MEASUREMENT test. During one portion of the RESISTANCE MEASUREMENT test, the SDM does the following:
^ 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 DRIVER HIGH and 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:
- Inflatable restraint steering wheel module.
- Inflatable restraint steering wheel module coil.
- Harness wiring of CKT 347.
- Harness wiring of CKT 348.
- Connector terminal contact.

The RESISTANCE MEASUREMENT test checks for this malfunction. This test only occurs once each ignition cycle when 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 lamp.

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.
- Once 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 can cause an intermittent condition:
^ A short circuit between CKT 347 and CKT 348.
^ A short circuit between CKT 347 and CKT 1403.
^ A short circuit between CKT 347 and CKT 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 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. Intermittent Problems
When a wire, connector or terminal repair is requested, use J 38125-A 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 CKT 347 to CKT 348.
12. This test checks for a short from CKT 347 to CKT 1404.