B1148

Diagnostic Chart:

Wiring Diagram:

Circuit Description
When you turn the ignition switch to the RUN position, the inflatable restraint Side Impact Sensing Module (SISM) performs tests to diagnose critical malfunctions within itself. The SISM then tests for the following conditions:
^ Deployment loop open
^ Deployment loop short to ground
^ Deployment loop short to ignition
^ Deployment loop resistance high
^ Deployment loop resistance low
^ Deployment reserve energy failure
The inflatable restraint Side Impact Sensing Module (SISM) transmits a pulse width modulated signal to the inflatable restraint Sensing and Diagnostic Module (SDM) over CKT 2108. A 300 millisecond pulse width with a 50 percent duty cycle is the Normal mode and indicates that the SISM is operating normally and no faults exist. The SISM communicates that it is turning OFF (ignition OFF) by sending a 20 millisecond pulse width modulated signal with a 50 percent duty cycle.

Conditions for Setting the DTC
The SDM receives a pulse width signal other than the Normal signal, or no signal at all. The SISM performs tests during POWER-ON tests, CONTINUOUS MONITORING tests, and Asynchronously.

Action Taken When the DTC Sets
^ The SDM sets DTC B1148.
^ The SDM commands the instrument panel cluster (IPC) to turn ON the AIR BAG warning lamp.

Conditions for Clearing the DTC
^ Current DTC
- The SDM receives a Normal signal from the SISM.
- The ignition switch is cycled.
^ History DTC:
- You issue a scan tool CLEAR CODES command.
- 250 malfunction-free ignition cycles occur. If a side impact deployment occurs the SISM must be replaced. Follow the instructions in the diagnostic table.

Diagnostic Aids
A poor connection can cause an intermittent condition. Check the following for a poor connection:
^ The SISM.
^ The inflatable restraint side impact inflator module.
^ The SDM terminal 14.
^ The wire to terminal connections of all circuits going to the SISM.

If you suspect that the SISM may be the cause of the malfunction, you can switch the SISMs in order to verify an internal SISM malfunction.

When measurements are requested in this table, use J 39200 Digital Multimeter with the correct terminal adapter from J 35616-A Connector Test Adapter Kit. When a check for proper connection is requested, refer to Intermittents and Poor Connections. When a wire, connector or terminal repair is requested, use J 38125-A Terminal Repair Kit and refer to Wiring Repair. Intermittent Problems Service and Repair

Test Description
The numbers below refer to step numbers on the diagnostic table.
2. If the passenger inflatable restraint side impact inflator deployed, B1148 will set.
3. Components require inspection and possibly replacement after a side impact accident, whether deployment occurred or not.
9. This test determines if the malfunction is in the inflatable restraint side impact inflator module.
15. This test checks for an open in CKT 1751.
17. This test checks for an open in CKT 1139.
19. This test checks for a short-to-ground in CKT 2104.
21. This test checks for an open in CKT 2104.
23. This test checks for a short-to-voltage in CKT 2104.
25. This test checks for a short-to-voltage in CKT 2103.
27. This test checks for a short-to-voltage in CKT 2103.
29. This test checks for high resistance or open in CKT 2103.
31. This test checks for a short-to-ground in CKT 2108.
33. This test checks for a short-to-voltage in CKT 2108.
39. This test checks for an open in CKT 2108.
41. If all wiring and connections are OK, then and only then should the inflatable restraint Side Impact Sensing Module (SISM) be replaced.