501-20A Safety Belt System: Description And Operation (page 3 of 4)

The retractor of each front safety belt is attached to the related B pillar. The webbing runs from the retractor through an 
upper mounting, attached to a shoulder height adjuster on the B pillar, to an anchor point on the front seat. 
 
On NAS vehicles, a tension sensor is integrated into the anchor point of the passenger front safety belt. The tension 
sensor is part of the occupant classification system. For additional information, refer to   

Air Bag and Safety Belt 

Pretensioner Supplemental Restraint System (SRS)

 (501-20B Supplemental Restraint System) 

 
 
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 restraints control module, 
which uses the input to determine the air bag and pretensioner activation strategies. The restraints control module also 
relays the status of the safety belts to the instrument cluster on the high speed CAN bus. 
 

Belt Minder Function (Where Fitted) 

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 medium speed CAN bus messages, from the 
restraints control module, to monitor the status of the front safety belts. 
 
When the ignition switch is turned to position II, 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 position II 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. 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 switch is turned to position 0.  
The vehicle speed decreases to 5 km/h (3 mph).  

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 turning the ignition switch to position 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 
T4. 
 

Safety Belt Warning Indicator