Supplemental Inflatable Restraint (SIR)

Diagnostic Chart:

CIRCUIT DESCRIPTION
When you first turn the ignition switch to the RUN position, the inflatable restraint control module performs tests to diagnose critical malfunctions within itself. Next the inflatable restraint control module measures IGNITION 1 and the deployment loop voltages to make sure they are within their respective normal voltage ranges. Then the inflatable restraint control module proceeds with the RESISTANCE MEASUREMENT test. During one portion of the RESISTANCE MEASUREMENT test, the inflatable restraint control module does the following:
^ 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 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 1 is within the normal operating voltage range.

ACTION TAKEN WHEN THE DTC SETS
^ The inflatable restraint control module sets a diagnostic trouble code.
^ The inflatable restraint control module turns ON the AIR BAG warning lamp.

CONDITIONS FOR CLEARING THE DTC
^ 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.
- 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
A poor connection can cause an intermittent condition. Check 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 inflatable restraint control module terminals 3 and 2.
^ The wire to terminal connections in CKT 347.
^ The wire to terminal connections in CKT 348.

DTC TABLE TEST DESCRIPTION
Number(s) below refer to step number(s) on the diagnostic table.
2. This test determines the deployment loop resistance measured by the inflatable restraint control module.
3. This test checks for proper contact and/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 located near the base of the steering column.
11. This test determines whether the malfunction is in the inflatable restraint steering wheel module coil or the inflatable restraint steering wheel module.
12. This test checks for proper contact and/or corrosion of the inflatable restraint control module connector.
14. This test checks for proper contact and/or corrosion of the inflatable restraint control module connector.
19. This test determines whether the malfunction is in CKT 347.
21. This test determines whether the malfunction is in CKT 348.