Air Bag Systems

Schematic:

CIRCUIT DESCRIPTION
When you first turn ON the ignition, the inflatable restraint sensing and diagnostic and seat belt pretensioner module (SDM) performs tests to diagnose critical malfunctions within itself. Then, the SDM proceeds with the RESISTANCE MEASUREMENT test to measure the deployment loop resistances to ensure they are within their respective normal resistance ranges. During one portion of the RESISTANCE MEASUREMENT test, the SDM does the following:
^ Measures the voltage difference between the driver frontal high and the driver frontal low circuits
^ Uses the measured voltage to calculate the resistance of the driver frontal air bag deployment loop

Upon passing these tests, the energy reserve is charged and the firing transistors are tested. The SDM then goes into CONTINUOUS MONITORING mode.

CONDITIONS FOR RUNNING THE DTC
When the ignition voltage is within the normal operating voltage range, the SDM performs the RESISTANCE MEASUREMENT test in order to calculate the resistance of the driver frontal air bag deployment loop.

CONDITIONS FOR SETTING THE DTC
The calculated resistance of the driver frontal air bag deployment loop is below 2.3 Ohm.

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

CONDITIONS FOR CLEARING THE DTC
^ You can issue a CLEAR CODES command.
^ A history DTC will clear once 255 malfunction free ignition cycles have occurred.

DIAGNOSTIC AIDS
The following can cause an intermittent condition:
^ The inflatable restraint steering wheel module coil integral connector.
^ The inflatable restraint steering wheel module coil wiring harness connector.
^ The wire to terminal connections in the driver frontal high circuit.
^ The wire to terminal connections in the driver frontal low circuit.
^ Refer to Testing for Intermittent and Poor Connections in Wiring Diagrams. Diagrams

TEST DESCRIPTION

Steps 1 - 6:

Steps 7 - 11:

The numbers below refer to step numbers on the diagnostic table.
2. This step checks the inflatable restraint steering wheel module coil integral connector.
4. This step checks to see if the inflatable restraint steering wheel module is defective.
6. This step checks to see if the inflatable restraint steering wheel module coil is defective.
8. This step determines if there is a short between the driver frontal high and the driver frontal low circuits or if there is a malfunctioning SDM.
11. This step clears all DTCs.