Circuit Description
The inflatable restraint sensing and diagnostic module (SDM) contains a sensing device that converts vehicle velocity changes to an electrical signal. The SDM processes the generated electrical signal and compares it to a value stored in memory. When the generated signal exceeds the stored value, the SDM performs additional signal processing and compares the generated signals to signals stored in memory. When two of the generated signals exceed the stored values, the SDM will cause current to flow through the frontal inflator modules and the pretensioners. This deploys the frontal air bags and the pretensioners and causes DTC B1151 and DTC B1152 to set. DTC B1153 will set with DTC B1151 and DTC B1152 when a deployment occurs while a frontal deployment circuit malfunction is present.
Conditions for Setting the DTC
The SDM detects a frontal crash, up to 30 degrees off the centerline of the vehicle, of sufficient force to warrant deployment of the frontal air bags and pretensioners, and a deployment circuit malfunction is present.
Action Taken When the DTC Sets
| • | The SDM sets a Diagnostic Trouble Code (DTC). |
| • | The SDM commands the instrument cluster (IPC) to turn ON the AIR BAG warning lamp. |
| • | The SDM records crash data. |
| • | The SDM sends a message over the class 2 serial data line. |
Conditions for Clearing the MIL/DTC
A scan tool Clear DTCs command is received by the SDM.
Diagnostic Aids
DTC B1153 will be accompanied by another DTC (besides DTC B1151 and DTC B1152). Repair the malfunction causing the other DTC(s) before diagnosing DTC B1153.
Test Description
The numbers below refer to the step numbers on the diagnostic table:
-
If the frontal inflator module(s) has not deployed, DTC B1151/B1152 may have set falsely.
-
If DTC B1151/B1152/B1153 has set with no signs of frontal impact, the DTC has set falsely.
-
This test checks for an SDM malfunction setting the DTC.
-
DTC B1151/B1152/B1153 may have set falsely while diagnosing the vehicle.
CAUTION: Be careful when you handle a sensing and diagnostic module (SDM). Do
not strike or jolt the SDM. Before applying power to the SDM:
• Remove any dirt, grease, etc. from the mounting surface • Position the SDM horizontally on the mounting surface • Point the arrow on the SDM toward the front of the vehicle • Tighten all of the SDM fasteners and SDM bracket fasteners to
the specified torque value
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the SIR Diagnostic System Check performed? | -- | ||
Turn the ignition switch OFF. Did the frontal inflator module deploy? | -- | |||
Inspect the front of the vehicle and the undercarriage for signs of impact. Are there signs of impact? | -- | |||
Replace components and perform inspections as required following an accident. Refer to Repairs and Inspections Required After a Collision . Have the appropriate inspections and repairs been made? | -- | -- | ||
5 | Replace the inflatable restraint sensing and diagnostic module (SDM). Refer to Inflatable Restraint Sensing and Diagnostic Module Replacement . Have the repairs been completed? | -- | -- | |
Reconnect all the SIR system components, make sure all the components are properly mounted. Have all the SIR components been reconnected and properly mounted? | -- | -- |
