Shoulder Belt Operation

The PRCM controls shoulder belt operation according to conditions detected by the PRCM through inputs received from various switches (door switches, limit switches, keyminder switch, and ignition switch). The PRCM receives these signals and operates the shoulder belts according to its internal program. The following information explains how the PRCM operates the shoulder belts, according to different operating conditions the PRCM will encounter.

NORMAL OPERATION
The shoulder belt moves to the B-pillar when the ignition is ON and the door is closed, or the vehicle speed exceeds 21 km/h (13 MPH).

The shoulder belt moves to the A-pillar when the door opens and vehicle speed is less than 21 km/h (13 MPH).

For the driver's side only, the shoulder belt moves to the A-pillar if the ignition is off and the key is out of the ignition.

DEFAULT STATE OPERATION
If the ignition is off, the driver's shoulder belt at the A-pillar and a door opens on one side of the vehicle to wake up the PRCM, the shoulder belt for the other door remains at the present location.

SECOND ATTEMPT
If a shoulder belt is unable to reach the destination determined by the PRCM, another attempt is made as soon as the vehicle speed exceeds 21 km/h (13 MPH).

RESPONSE TO A FAILED DOOR SWITCH
If the vehicle speed exceeds 21 km/h (13 MPH) with a door open, or the door switch failed, indicating an open door, the PRCM will attempt to drive the shoulder belt to the B-pillar. The shoulder belt will not be driven to the A-pillar until at least one of the following conditions are met:
- Vehicle speed is less than 21 km/h (13 MPH), and the door switch has cycled indicating door closure, then cycled indicating door opening.
- Ignition is off, and the door switch indicates the door is open.
- For driver's side shoulder belt only, the ignition is off, and the ignition key has been removed from the ignition switch.

HIGH SPEED DECELERATION
If a door opens within three seconds of a rapid vehicle deceleration, the shoulder belt remains at the B-pillar one of the following conditions are met:
- Vehicle speed is less than 21 km/h (13 MPH), and the door switch has cycled indicating door closure, then cycled indicating door opening.
- Ignition is off, and the door switch indicates the door is open.
- For driver's side shoulder belt only, the ignition is off, and the ignition key has been removed from the ignition switch.
- If an apparent rapid deceleration occurs due to turning the ignition off (which terminates the vehicle speed pulses), the belts will not move for the next three seconds, even if a door opens.

The deceleration condition causing the responses specified above must be such that the vehicle speed decreases from a speed above 21 km/h (13 MPH) to a speed below 21 km/h (13 MPH) in a rapid manner.


MOTOR SHUTDOWN
When a pillar switch opens indicating the belt has reached its destination, the module de-energizes the belt motor.

STALL TIME-OUT
If a belt motor has been energized for more than 15 seconds, the PRCM will deenergize the motor.

DELAY ON BELT MOTION REVERSAL
If the belt is moving towards a selected destination, and the destination changes while the belt is in motion, the PRCM will deenergize the motor for 0.5 seconds before energizing the motor in the opposite direction. (For example, the belt is moving towards the B-pillar and the driver turns the ignition off and opens the door, the shoulder belt will stop for 0.5 seconds, then reverse, going back to the A-pillar.)

RESPONSE TO FAILED PILLAR LIMIT SWITCHES
The PRCM determines if a limit switch fails so that the belt appears to be at both pillars simultaneously. So, no matter which destination is selected, the PRCM will energize the motor for 15 seconds to drive the belt toward the selected destination. The PRCM determines the selected destination according to received inputs and its own internal program.