Seat Belt Systems: Description and Operation
Safety Belt System
COMPONENT LOCATION
Safety Belt System:
INTRODUCTION
A three point safety belt is installed in all seating positions. Each seatbelt has Emergency locking retractor (ELR) functionality.
The ELR function incorporates a lift shaft locking system with webbing sensor and car sensing activating mechanisms. The webbing sensor activates the locking mechanism if the webbing is subjected to a sharp pull. The car sensor activates the locking system if the vehicle is subjected to sudden deceleration or severe tilt angle.
All second row passengers and NAS front Passenger ELR's are enhanced with Automatic Locking Retractors (ALR).
The ALR allows webbing to be extracted to activate a ratchet device. This device allows webbing to be cinched tight to facilitate child seat fitment. With seatbelt webbing tensioned in ALR mode the seatbelt is always locked.
All row 1 driver and passenger ELRs incorporate an electrically activated webbing tension reducer (comfort device). This device is activated at vehicle ignition on and insertion of seatbelt tongue into buckle.
A safety belt warning indicator is installed in the instrument cluster to remind the front seat occupants to fasten their safety belts. The warning indicator illuminates if the safety belt of an occupied front seat is not fastened. On NAS vehicles the beltminder system will ignore the state of the passenger safety belt for the first 75 seconds after ignition on. The warning indicator remains illuminated until the safety belt of each occupied front seat is fastened, or the ignition is switched off.
FRONT SAFETY BELTS
The retractor of each front seatbelt is attached to the related B pillar mounting bracket. The webbing runs from the retractor through a fixed D loop bracket mounted to B pillar upper to an anchor point on the sill.
The retractor for each front safety belt incorporates a load limiter that allows the retractor reel to partially unwind when the load on the webbing exceeds a predetermined limit.
The buckle for each front safety belt is attached to a pretensioner secured to the inboard side of the related front seat frame. Each buckle incorporates a safety belt buckle sensor that provides a status input to the RCM (restraints control module), which uses the input to determine the air bag and pretensioner activation strategies. The RCM (restraints control module) also relays the status of the safety belts to the instrument cluster on the high speed CAN (controller area network) bus.
Belt Minder Function
Safety Belt Warning Indicator
The belt minder function provides warnings to the driver if the appropriate front safety belts are not fastened when driving.
The belt minder function is controlled by the instrument cluster using:
- High speed CAN (controller area network) bus messages, from the RCM (restraints control module), to monitor the status of the front safety belts.
- An input from the occupant detection system to monitor the status of the front passenger seat.
When the ignition is switched to on, the instrument cluster illuminates the safety belt warning indicator until one of the front safety belts is fastened or the belt minder function is triggered. The belt minder function is triggered when the ignition switch is in accessory/convenience and the following conditions coexist:
- The belt minder function is enabled.
- Vehicle speed is 8 km/h (5 mph) or more.
- The vehicle is not in reverse.
- The driver safety belt or, if the front passenger seat is occupied, the front passenger safety belt, is unfastened.
When the belt minder is triggered, the instrument cluster generates the following warnings for 10 seconds.
- Flashes the safety belt warning indicator at 2 Hz.
- Sounds a repeating chime in sequence with the flashing safety belt warning indicator.
After 10 seconds, the repeating chime is discontinued and the safety belt warning indicator changes from flashing to continuously illuminated for 20 seconds. While the trigger conditions still coexist, the warnings are repeated every 30 seconds until one of the following occurs:
- 5 minutes has elapsed from when the warnings were first triggered.
- The safety belt of each occupied front seat is fastened.
- The ignition mode is position 0.
- The vehicle speed decreases to 5 km/h (3 mph).
For non NAS vehicles the belt minder function can be enabled and disabled using the driver safety belt switch. The instrument cluster changes the state of the belt minder function if, within 60 seconds of first entering ignition mode II, the driver safety belt is fastened and unfastened nine times. Successful completion of the change is indicated by a single chime and the safety belt warning indicator flashing five times, at 2 Hz. The belt minder function can also be enabled and disabled using IDS.
SECOND ROW SAFETY BELTS
The retractor of each second row safety belt is attached to the rear shelf immediately behind the seat. The retractors are located in the center of the shelf. The webbing runs from the retractor, to an anchor point in the center of the vehicle either side of the transmission tunnel. The seat belt buckles are attached to the vehicle body on the outer side of the seat.