Medium Speed Controller Area Network (MS-CAN)
Air Bag and Safety Belt Pretensioner Supplemental Restraint System (SRS)
Medium Speed Controller Area Network (MS-CAN)
This vehicle utilizes a communication system called a Medium Speed Controller Area Network (MS-CAN). The RCM communicates with various modules for required information about the vehicle. Refer to Module Communications Network Description and Operation for additional information about the MS-CAN.
Occupant Classification Sensor (OCS) System
The OCS system is found only on the front passenger seat. The OCS system is comprised of a silicone gel-filled bladder mounted between the seat cushion foam and half pan, a pressure sensor and OCSM that are mounted to the cushion half pan. Pressure is applied to the OCS system bladder when weight of any occupant or object in the front passenger seat is present. The pressure is then transferred through a tube, sensed by the OCS system pressure sensor, then electronically communicated to the OCSM.
The OCS system is also used for operation of the passenger Belt-Minder(R). For information on the passenger Belt-Minder(R) feature, refer to Safety Belt System Description and Operation. To deactivate or reactivate the passenger Belt-Minder(R) feature, refer to Instrumentation and Warning Chimes Testing and Inspection or the Owner's Literature.
Belt Tension Sensor (BTS)
The Belt Tension Sensor (BTS):
- is a 3-wire Hall-effect sensor located at the safety belt anchor point and is part of the front passenger safety belt and retractor assembly.
- is used in conjunction with the OCS system.
The BTS is used by the OCS system to identify the presence of a child safety seat on the front passenger seat. The BTS senses the tension on the safety belt assembly then provides an output to the OCSM, indicating that the safety belt assembly is cinched. After sensing the weight applied to the seat by the occupant or using the safety BTS input, the OCSM determines how the occupant should be classified and communicates this information to the RCM. If the occupant is classified as a child, the RCM will then automatically deactivate the passenger air bag module and illuminate the Passenger Air Bag Deactivation (PAD) indicator.
Passenger Air Bag Deactivation (PAD) Indicator
The RCM controls the state of the PAD indicator, based on information provided by the OCSM system. The PAD indicator is illuminated to indicate the passenger air bag module is disabled. An exemption to this is when the front passenger seat is determined to be empty, and therefore indication of a deactivated passenger air bag module is not necessary. In all other cases, the PAD indicator is off when the passenger air bag module is enabled.
The RCM briefly activates the PAD indicator to prove-out the indicator function and verify to the front occupants correct function operation of the PAD indicator.
The following table indicates the passenger air bag status and the PAD indicator status based on the size of the front passenger occupant.
Passenger Air Bag and Passenger Air Bag Deactivation (PAD) Indicator Status
Passenger Air Bag Module
The passenger air bag module is a dual-stage air bag, deploying at 1 of 2 different rates depending upon vehicle impact severity and sensor input.
Restraints Control Module (RCM)
WARNING: If a vehicle has been in a crash, inspect the restraints control module (RCM) and the impact sensor (if equipped) mounting areas for deformation. If damaged, restore the mounting areas to the original production configuration. A new RCM and sensors must be installed whether or not the air bags have deployed. Failure to follow these instructions may result in serious personal injury or death in a crash.
The RCM carries out the following functions:
- Deploys the air bag(s) in the event of a deployable collision
- Activates the driver and passenger safety belt retractor pretensioner(s) to control the tension of the driver and passenger safety belts in the event of a deployable collision
- Monitors the SRS for faults
- Sends a message to the IC module to illuminate the air bag warning indicator if a fault is detected
The RCM monitors the SRS for possible faults. If a fault is detected, the RCM will request the IC module to illuminate the air bag warning indicator. When the ignition is turned OFF and then ON, the IC module will prove out the air bag warning indicator by lighting for 6 seconds. If no faults are detected by the RCM, the IC module will turn the air bag warning indicator off and it will remain off. If the RCM detects a fault, it will send a message to the IC module to turn the air bag warning indicator on and it will remain on for the rest of the ignition cycle. If the RCM requests illumination of the air bag warning indicator and the air bag warning indicator does not function, the IC module will automatically activate an audible chime.
The RCM includes a backup power supply. This feature provides sufficient backup power to deploy the air bags in the event that the ignition circuit is lost or damaged during impact. The backup power supply will deplete its stored energy approximately one minute after power and/or ground has been removed from the RCM.
Safety Belt Buckle Switches
The safety belt buckle switches indicate to the RCM whether the safety belts are buckled or unbuckled.
The RCM also communicates the driver safety belt buckle switch status to the IC module, which monitors the information to control the safety belt warning indicator. For information on the safety belt warning indicator, refer to Instrumentation and Warning Chimes Testing and Inspection.
Safety Belt Retractor Pretensioner
The safety belt retractor pretensioners remove excess slack from the safety belt webbing. The pretensioners are activated by the RCM when the module detects a crash event force exceeding a programmed limit.
Seat Track Position Sensor
The seat track position sensor indicates to the RCM the position of the seat, forward or rearward. The RCM uses this information in determining the deployment rate of the dual-stage driver/passenger air bag module.
Secondary Air Bag Warning (Chime)
The secondary air bag warning chime is an audible chime located in and controlled by the IC module. If a fault is detected with the air bag warning indicator, a DTC will be stored in memory of the IC module. After receiving the message from the RCM that a SRS fault has been detected, the IC module will sound the secondary air bag warning chime in a pattern of 5 sets of 5 beeps.
Impact Sensors
For this vehicle line, the SRS uses 4 satellite sensors in addition to the RCM. The RCM is mounted to the center tunnel beneath the console. All vehicles have 2 front impact severity sensors located in the front of the vehicle. The side impact sensors are mounted at the base of each B-pillar. Mounting orientation is critical for correct operation of all impact sensors.
Seat Side Air Bag Module
The seat side air bag module:
- will deploy upon receiving a flow of current from the RCM.
- is mounted in the seat backrest.