Supplemental Restraint System

The SRS is controlled by the RCM, which continually monitors various inputs. When these inputs indicate a frontal or side crash, the RCM may deploy some components, based upon the severity of the crash and the sensor inputs.

Although some deployable devices may not have activated for all occupants during a crash, it does not mean that something is wrong with the SRS.

The RCM performs a self-test of the complete SRS during each startup. In addition to the self-test at start up, the RCM continuously monitors all of the SRS components and circuitry for correct operation.

Airbag Component Connectors 

The SRS utilizes Connector Position Assurance (CPA) tabs on connectors to deployable components. The Connector Position Assurance (CPA) tabs disengage shorting bars in the deployable component connector from its electrical pins and keeps the harness connector securely attached to the deployable component.

If the connector is attached to the deployable component without the tabs fully seated, the pins of the connector still make contact with the deployable component pins. However, because the tabs are not fully seated and the shorting bars are still applied to the deployable component pins, the RCM detects a fault (circuit resistance below threshold) during self-test diagnostics when the vehicle is powered on and will illuminate the airbag warning indicator.

Airbag Second Stage Deployment Check 

The driver and passenger front airbags each have 2 deployment stages. After an airbag deployment, it is possible that stage 1 has deployed and stage 2 has not. If a front airbag has deployed, it must be remotely deployed using the appropriate airbag disposal procedure to make sure both stages have been deployed. For information on driver airbag and/or passenger airbag remote deployment, Refer to: Pyrotechnic Device Disposal .

Airbag Warning Indicator 

The airbag warning indicator:

• proves out by lighting for 6 seconds and then turning off.
• flashes and/or illuminates based on the message the IPC receives from the RCM.
• illuminates if the IPC does not receive a message from the RCM.

When the ignition is turned on during normal operation, the IPC illuminates the airbag warning indicator continuously for 6 seconds. If the SRS is free of faults, the airbag warning indicator turns off and remains off. If a SRS fault exists, the airbag warning indicator illuminates and remains illuminated for the rest of the ignition cycle. The RCM communicates with the IPC via the HS-CAN. The IPC illuminates the airbag warning indicator based on messaging from the RCM. The IPC also illuminates the airbag warning indicator if there is no communication between the RCM and IPC.

Body Control Module (BCM) 

The BCM provides system voltage to the RCM and OCSM when the ignition is ON. Additionally, the BCM is designed to ensure the RCM and OCSM remain powered on if the ignition is turned off while the vehicle is moving at a speed greater than 4 km/h (2.5 mph).

If the ignition signal is active / high while the vehicle is travelling at a speed above 4 km/h (2.5 mph) the BCM maintains system voltage on the RCM and OCSM power supply circuits. If the ignition signal is lost, missing, or below a certain threshold while the vehicle is travelling at a speed above 4 km/h (2.5 mph), the BCM maintains system voltage on the RCM and OCSM power supply circuits and a telltale appears in the IPC. If the vehicle speed rises above the threshold again, the BCM does not reactivate the power supply to the RCM and OCSM. They remain off until the ignition is turned on again.

If a vehicle is parked with the ignition off, the BCM does not provide power to the RCM and OCSM. If the vehicle begins to move while the ignition is still off, the BCM does not power the RCM or OCSM.

When the vehicle has been started using the remote start feature (if equipped), the ignition status is off, but the BCM powers the RCM in order to detect a collision and disable the fuel pump, if necessary.

Event Notification Signal 

The event notification feature provides other vehicle subsystems with information pertaining to SRS deployment or fuel cutoff status. When an impact occurs which exceeds a pre-determined threshold, the RCM sends a signal on a dedicated circuit to the BCM.

When the BCM receives the crash signal input, it initiates fuel cutoff to disable the fuel system.

After the fuel system is disabled, the vehicle can be re-started after carrying out the following steps:

• Turn the ignition on and wait 10 seconds.
• Turn the ignition off.
• Turn the ignition on.
• Turn the ignition off.
• Turn the ignition on.

Occupant Classification System (OCS) 

The OCS classifies the size of the front passenger seat occupant and provides this information to the RCM.

Pressure is applied to the OCS bladder when weight of any occupant or object in the front passenger seat is present. The pressure is then transferred through a tube and sensed by the OCS pressure sensor within the OCSM. The OCSM sends information concerning the weight of any occupant or object on the front passenger seat to the RCM via the HS-CAN. The RCM uses this information when determining if the passenger airbag or side airbag needs to be deployed in the event of a crash.

The OCS is also used for operation of the passenger Belt-Minder®. For information about Belt-Minder®, Refer to: Seatbelt Systems .

To deactivate or reactivate the passenger Belt-Minder® feature, Refer to: Seatbelt Minder Deactivating/Activating .

Passenger Airbag Deactivation (PAD) Indicator 

The PAD indicator is controlled by the RCM through two direct hard-wired connections based on messages received from the OCS on the HS-CAN2. One of two LEDs (light emitting diodes) are illuminated to indicate the passenger airbag status.

The RCM briefly activates the PAD indicator LEDs (light emitting diodes) to verify indicator function and verify proper functional operation of the PAD indicator to the front occupants.

The following table indicates the passenger airbag and PAD indicator status based on the front passenger seat occupant:

SOS Post-Crash Alert System™ 

The SOS Post-Crash Alert System™ is controlled by the BCM, but initiated by the RCM.

When a deployment or fuel cutoff event occurs, the RCM sends a message on the HS-CAN2 (via the GWM) to the BCM. The BCM flashes the turn signal lamps and sounds the horn (except when 911 Assist™ is active) until it is turned off. The system can be turned off 10 seconds after a crash event by pressing the hazard switch. The BCM also unlocks the doors and illuminates the courtesy lamps after a crash event. Refer to MULTIFUNCTION ELECTRONIC MODULES for more information.

Vehicle Spin-out Detection 

When internal RCM sensors detect that the vehicle has spun out, the ABS module receives this data on a dedicated HS-CAN and sends a message to the BCM on the HS-CAN2 (via the GWM). The BCM then activates the hazard warning flashers and displays a message in the IPC to indicate the hazard warning flashers are activated due to the spin-out.