Supplemental Inflatable Restraint (SIR)

Diagnostic Chart:

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 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 ignition is within normal operating voltage range.
^ The measured leakage currents to ground in the passenger frontal air bag deployment loop are above a specified value caused by a short circuit from the passenger frontal air bag deployment loop to ground.

DTC 23 will set once one of these conditions is met. This test is run during the SDM Turn-ON tests.

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 23 to set are no longer existing, History DTC 23 will set. History DTC 23 may be cleared using the scan tool.

Diagnostic Aids
An inflatable restraint IP module circuit short-to-ground or a short circuit between the communication signal return line of the LH or RH inflatable restraint Side Impact Sensor (SIS) can cause an intermittent condition. Inspect CKTs BA10 and BP10 carefully for cutting and/or chafing. A careful inspection of the circuits and components indicated on the DTC 23 Table is essential to make sure that the replacement SDM will not be damaged. Also inspect CKTs XB42 and XM430 carefully for cutting and/or chafing.

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

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

7. This test determines whether the malfunction is in the inflatable restraint IP module. This is done by substituting the known good resistance of the load tool and then observing if the malfunction is still present.
9. This test determines whether the malfunction is in CKT BA10.
11. This test determines whether the malfunction is in CKT BP10.