Supplemental Inflatable Restraint (SIR)

Wiring Diagram:

Circuit Description
The inflatable restraint Sensing and Diagnostic and Seat Belt Pretensioner Module (SDM) preforms tests to diagnose critical malfunctions within itself when the ignition switch is turned ON. The SDM monitors the six firing loops to detect leakage currents to ground and system voltage in the frontal and side air bag inflator module and seat belt pretensioner circuits. The deployment loop resistances are measured to ensure they are within their respective normal resistance ranges. The SDM does the following during one portion of the RESISTANCE MEASUREMENT test:

^ Measure the voltage difference between the DRIVER BELT HIGH and the DRIVER BELT LOW.
^ Uses the measured voltage to calculate the resistance of the driver pretensioner deployment loop.

Upon passing these tests, and if the energy reserve is charged up, the firing transistors are tested. The SDM then goes into Continuous Monitoring mode The SDM service wait time is 1 minute. Refer to Air Bag(s) Arming and Disarming.

Conditions for Setting the DTC
The driver seat belt side buckle pretensioner deployment loop resistance is less than 1.0 Ohms. The driver seat belt side buckle pretensioner deployment loop consists of the following components.

^ Driver seat belt side buckle pretensioner.
^ Harness wiring of CKT AM900 and CKT AM950.
^ Harness wiring of CKT XM901 and CKT XM950.
^ Connector terminal contacts, including shorting bars.

The deployment loop resistance test checks for this malfunction.

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 DTC
Current and History DTC codes must be cleared using a scar tool Clear DTC Information command. If the circuit fault has been successfully repaired and the conditions which caused the Current DTC 36 to set are no longer existing, History DTC 36 will set. History DTC 36 be cleared using the scan tool.

Diagnostic Aids
Inspect CKT's AM900, AM950, XM901 and XM950 carefully for cutting and/or chafing. The diagnostic table directs the technician to note the value of LH PRETENS RESIST. Comparing the value of LH PRETENS. RESIST. over multiple ignition cycles can be helpful it determining if an intermittent condition exists.

When measurements are requested in this table, use J 39200.

Test Description
The numbers below refer to step numbers on the diagnostic table

2. This test determines the deployment loop resistance measured by the inflatable restraint sensing and diagnostic module.
8. This test checks for proper contact or corrosion of the SDM harness connector.
10. This test checks for a short from CKT AM900 to CKT XB901.
13. This test checks for a short from CKT AM900 or AM950 to CKT XM901 or XM950.
15. This test checks for a short in the driver pretensioner seat harness.
16. This test determines whether the malfunction is in the driver pretensioner belt assembly. This is done by substituting the known good resistance of the load tool and then observing if the malfunction is still preset it.