Seat Belt Systems: Description and Operation

FASTEN SAFETY BELT INDICATOR
The Instrument Panel Cluster (IPC) illuminates the fasten safety belt indicator when the following occurs:
^ The Body Control Module (BCM) detects that the driver's seat belt is unbuckled. The IPC receives a class 2 message from the BCM requesting illumination. The IPC illuminates the indicator for 20 seconds and then flashes the indicator for 55 seconds. The IPC sends a class 2 message to the BCM indicating the indicator is illuminated. The BCM sends a class 2 message to the radio in order to activate an audible warning.
^ The IPC performs the displays test at the start of each ignition cycle. The indicator illuminates for approximately 3 seconds.
^ The IPC detects a loss of class 2 communications with the BCM.

RESTRAINT SYSTEM
Seat belts are the primary means of occupant restraint. Seat belts help keep the occupants inside the passenger compartment, and gradually reduce the impact forces during the following events:
^ Frontal impact type crashes
^ Rear impact type crashes
^ Side impact type crashes
^ Roll-over type crashes

All seat belt retractors have emergency locks. The retractors remain unlocked during normal operation and under normal driving conditions. The retractors remain unlocked during normal conditions in order to allow free movement of the upper body to each occupant.

A pendulum locks the seat belt webbing into position. The pendulum causes a locking bar to engage a cog on the spool of the retractor mechanism when the following conditions occur:
^ A rapid extraction of the seat belt webbing from the retractor
^ An abrupt change in the vehicle speed
^ An abrupt change in the vehicle direction
^ Operation of the vehicle on a steep upgrade
^ Operation of the vehicle on a steep downgrade

The seat belts have an automatic locking feature, known as the cinch feature. After buckling the seat belt, pulling on the shoulder belt will cause the lap belt to tighten and hold.

Use of the cinch feature is recommended for securing a child seat.

The cinch feature may be canceled by unbuckling the seat belt.

This vehicle is also equipped with a Supplemental Inflatable Restraint (SIR) system. Refer to SIR System Description and Operation in Restraint Systems.

FRONT SEAT SYSTEM
The front seat belt system includes the following components:
^ The driver and passenger seat buckle-side belts, attached to the inboard side of the seat frame
^ The driver and passenger seat retractor-side belts, attached to the lock pillar or center pillar

The driver seat belt system includes a seat belt switch in the driver seat buckle-side belt. The seat belt switch controls the fasten safety belt indicator and a tone alarm. The fasten safety belt indicator and the tone alarm will not operate when the following conditions exist:
^ The driver seat belt is buckled.
^ The driver door is closed.
^ The ignition switch is turned ON.

The following events will occur when the driver door is closed and the ignition switch is turned ON, but the driver seat belt is not buckled:
^ The tone alarm will operate for 4-8 seconds and then turn off.
^ The fasten safety belt indicator will operate until the driver seat belt is buckled, or until approximately 1 minute has elapsed.

Refer to Seat Belt Indicator Circuit Malfunction in order to diagnose faults in the fasten safety belt indicator or Diagrams in Body and Accessories in order to diagnose faults in the tone alarm.

REAR SEAT SYSTEM
The rear seat belt system includes the following components:
^ The rear seat buckle-side belt, attached to the floor panel inboard of the rear seats
^ The rear seat retractor-side belt, attached to the rear package shelf