B1021

Diagnostic Chart (Part 1 of 3):

Diagnostic Chart (Part 2 Of 3):

DTC B1021 Driver Deployment Loop Resistance High ( Part 3 Of 3):

Wiring Diagram:

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 then measures IGNITION 1 and the deployment loop voltages to verify that they are within their respective normal voltage ranges. The SDM then 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 more than 3.8 ohms.

The RESISTANCE MEASUREMENT test inspects for this malfunction. This test only occurs once each ignition cycle when IGNITION 1 voltage is within the normal operating voltage range.

ACTION TAKEN WHEN THE DTC SETS
The SDM turns ON the AIR BAG warning lamp.

CONDITIONS FOR CLEARING THE DTC
The DTC will clear when one of the following conditions is met:
^ Current DTC
The resistance of the driver deployment loop is less than 3.8 ohms and 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
A poor connection may cause an intermittent condition. Inspect the following for a poor connection:
^ The inflatable restraint steering wheel module steering column connector terminals A and B
^ The upper inflatable restraint steering wheel module coil connector terminals A and B
^ The SDM terminals 2 and 3
^ The wire to terminal connections in CKT 347
^ The wire to terminal connections in CKT 348

The diagnostic table directs the technician to note the entry value of 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 the J 39200 Digital MultiMate with the correct terminal adapter from the J 35616-A Connector Test Adapter Kit. When an inspection for proper connection is requested, refer to Testing for Intermittent and Poor Connections in Diagrams. When a wire, connector or terminal repair is requested, use the J 38125-B Terminal Repair Kit. Refer to Wiring Repairs in Diagrams.

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).
3. This test inspects for proper contact or corrosion of the yellow 2-way connector.
10. This test isolates the malfunction to one side of the inflatable restraint steering wheel module yellow 2-way connector.
11. This test determines whether the malfunction is due to the inflatable restraint steering wheel module or the module coil.
14. This test inspects for proper contact or corrosion of the SDM connector.
19. This test determines whether the malfunction is in CKT 347.
21. This test determines whether the malfunction is in CKT 348.