Supplemental Inflatable Restraint (SIR)

Diagnostic Chart:

Wiring Diagram:

Circuit Description
The inflatable restraint Sensing and Diagnostic and Seat Belt Pretensioner Module (SDM) performs TURN-ON 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. 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. 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 passenger frontal air bag deployment loop resistance is less than 1.1 Ohms. The passenger frontal air bag deployment loop consists of the following components.

^ Inflatable restraint IP module.
^ Harness wiring of CKT BA10.
^ Harness wiring of CKT BP10.
^ 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 scan tool Clear DTC Information command. If the circuit fault has been successfully repaired and the conditions which caused the Current DTC 34 to set are no longer existing, History DTC 34 will set. History DTC 34 may be cleared using the scan tool.

Diagnostic Aids
The following can cause an intermittent condition:

^ A short circuit between CKT BM30 and B30.
^ A malfunctioning shorting bar in the inflatable restraint IP module.
^ A malfunctioning shorting bar in the inflatable restraint IP module coil.
^ A malfunctioning shorting bar on the SDM harness connector above SDM harness connector terminals 3 and 4.

Inspect CKTs BA10 and BP10 carefully for cutting and/or chafing. The diagnostic table directs the technician to note the value of PASSENGER AIR BAG RES. Comparing the value of PASSENGER AIR BAG RES. over multiple ignition cycles can be helpful in 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.
3. This test checks for proper connection of the orange 2-way connector.
8. This test isolates the malfunction to one side of to the inflatable restraint IP module yellow 2-way connector. This is done by substituting the known good resistance of the load tool and then observing if the malfunction is still present.
10. This test checks for proper contact or corrosion of the SDM connector.
15. This test checks for a short from CKT BA10 to CKT BP1O.