DTC 026

Circuit Description
When the ignition switch is turned to the ON position, the Inflatable Restraint Sensing and Diagnostic and Seat Belt Pretensioner Module (SDM) performs tests to diagnose critical malfunctions within itself. The SDM monitors the six deployment loops to detect leakage currents to B+ in the frontal air bag deployment loops, the side air bag deployment loops and the seat belt pretensioner deployment loops. 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, the energy reserve is charged and the firing transistors are tested. The SDM then goes into CONTINUOUS MONITORING mode. The SDM service wait time is 1 minute. Refer to ENABLE/DISABLE procedures.

Conditions for Setting the DTC
^ The ignition is within normal operating voltage range.
^ The measured leakage currents to voltage are above a specified value caused by a short to voltage in the passenger seat belt pretensioner deployment loop.

Action Taken When the DTC Sets
^ The SDM sets a DTC 26.
^ 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 26 to set are no longer present, History DTC 26 will set. History DTC 26 may be cleared using the scan tool.

Diagnostic Aids
A short to voltage in the Passenger Seat Belt Pretensioner deployment loop can cause an intermittent condition. Inspect CKT AB950, CKT AB900, CKT XB950, and CKT XB901 carefully for cutting and/or chafing. A careful inspection of the circuits and components indicated on the DTC 26 Table is essential to make sure that the replacement SDM will not be damaged.

Test Description
The numbers below refer to step numbers on the diagnostic table.
2. This step checks to see if the Passenger Seat Belt Pretensioner is defective.
4. This step checks to see if terminal 45 or terminal 15 of the SDM wiring harness connector is damaged or corroded.
9. This step checks for a short to B+ in CKT AB950 or CKT AB900.
11. This step determines if there is a short to B+ in CKT XB950 or CKT XB901 or if there is a malfunctioning SDM.