Seat Belt System Description and Operation
Restraint System The primary means of occupant restraint are the front and rear seat belts. Seat belts help to keep the occupants inside the passenger compartment and gradually reduce the impact forces during the following events: Frontal impact Rear impact Side impact Rollover event All seat belt retractors have emergency locks. The retractors remain unlocked during normal operation and under normal driving conditions to allow free movement of the upper body of each occupant. The seat belt webbing is locked into position by a pendulum, which causes a locking bar to engage a cog on the spool of the retractor mechanism, when the following conditions occur: Rapid extraction of the seat belt webbing from the retractor Abrupt change in vehicle velocity Operation of the vehicle on a steep slope The seat belts have an automatic locking (cinch) feature. The cinch feature is activated when the seat belt webbing is completely extended from the retractor. It prevents the webbing from extending beyond the position at which it can retract. Use of the cinch feature is recommended for securing a child seat. The cinch feature may be cancelled by allowing the webbing to wind back completely into the retractor. After the cinch feature is cancelled, the webbing is unlocked. This vehicle is also equipped with a Supplemental Inflatable Restraint (SIR) system. Refer to Supplemental Inflatable Restraint System Description and Operation. Motorized Seat Belts A motorized seat belt is a seat belt with a motor coupled to the shoulder belt retractor. The motor performs a reversible, pretightening action (retraction) to reduce the slack in the seat belt. The motorized seat belt provides the driver and passenger a sense of safety and, in the case of severe braking or a crash, more quickly couples the occupant to the vehicle, enhancing the safety to the occupant. Motorized seat belts monitor vehicle information to determine when to perform each of the following retractions Full retraction for such situations but not limited to: panic braking and or skidding Dynamic support for lateral and longitudinal dynamics Slack removal when the vehicle speed above enable speed Preconditions for motorized seat belt retractions Seat belt buckle is latched Vehicle speed greater than or equal to 25 kph (16 mph) All messages on serial data are received as valid Triggers that may cause motorized seat belt retractions Sudden Emergency / Panic Braking High Vehicle Deceleration Detection Ice Braking Detection Oversteer and Understeer Motorized seat belt inputs Vehicle Power Mode Transmission Gear Wheel Speeds Vehicle Acceleration Accelerator Pedal Position Steering Wheel Angle and Gradient Yaw Rate and Lat/Long Acceleration Brake Pedal Position, Gradient, Pressure, Initial Travel Vehicle Stability Motorized seat belt output signals Driver information center message – motorized seat belt Failed “Service Automatic Seatbelt Tightening” Driver information center message – motorized seat belt Unavailable “Automatic Seatbelt Tightening Unavailable” Motorized seat belt retractions are inhibited when seat belt unbuckled Driver and passenger motorized seat belts operate independently Front Seat Belt System The front seat belt system includes the driver and passenger seat belts, seat belt reminder indicators, and the retractor and anchor pretensioners, which are part of the SIR system, refer to Supplemental Inflatable Restraint System Description and Operation. The driver seat belt reminder indicator is controlled by a switch in the driver seat belt buckle. The passenger seat belt reminder indicator is controlled by a switch in the passenger seat belt buckle and the Restraint Occupant Classification System Module. For more on the Restraint Occupant Classification System Module, refer to Supplemental Inflatable Restraint System Description and Operation. When the vehicle is on, the seat belt reminder indicator and tone alarm will operate in the following cases: The driver seat belt is unbuckled The passenger seat belt is unbuckled while the seat is occupied Rear Seat Belt System The rear seat belt system includes the following components: The rear seat belt retractor located at the wheelhouse panel and attached to the floor panel The rear seat belt buckles and the center seat belt buckle attached to the seat Child Seat Restraint System