Predictive occupant protection function - GF91.60-P-2010RT
MODEL 251 with CODE (299) PRE-SAFE with CODE (242) Electrically adjustable front passenger seat with memory up to Model Year 8
Block diagram for PRE-SAFE system shown with code 242 Electrically adjustable passenger seat with memory and code 414 electric glass tilting/sliding roof
General
The "PRE-SAFE foresighted occupant protection" safety system is both an active and passive safety device. As soon as a critically dangerous driving situation is detected by the brake system's sensor system, precautionary measures are introduced. The foresighted occupant protection system becomes effective beginning at a speed of 30 km/h (20 mph).
The given restraint system is extended to the extent that any unwanted motion by the driver or front passenger (only for electrically adjustable front passenger seat with memory equipment) when braking and skidding is reduced and the driver and front passenger are moved into an optimum seat position.
The PRE-SAFE safety system encompasses a package with the functions:
- Reversible electrical inertia reel emergency tensioning retractor
The control units for the foresighted passenger protection are located in the left front reversible emergency tensioning retractor and right front reversible emergency tensioning retractor installed in the B-pillars. Data is exchanged with the brake system over the Controller Area Network bus Class C (engine compartment) (CAN-C).
- Front seat conditioning
- Automatic closing of panoramic glass roof with code 413, Panoramic glass roof with top sliding roof or tilting/sliding roof code 414 Power glass tilting/sliding roof
Function
PRE-SAFE is triggered in the following critical driving situations:
PRE-SAFE longitudinal dynamics
- Emergency stop: Driver shocked into pressing all the way down on the brake pedal.
- Panic follow-up braking: Vehicle fails to decelerate sufficiently due to weather conditions (ice, snow, etc.). The driver panics and depresses the brake pedal.
- Powerful targeted braking: Brake Assist System introduces powerful targeted braking.
PRE-SAFE lateral dynamics
- Excessive oversteer: A major rear axle slip angle occurs, and cannot be stabilized by the Electronic Stability Program (ESP).
- Excessive understeer: A significant, pending front axle slip angle occurs for an extended period, and cannot be stabilized by ESP.
- Critical steering wheel motion: Driver's steering wheel motion, which may point to a startled response and which may result in vehicle instability. Triggering occurs first at speeds of >140 km/h (90 mph).
For all the above-mentioned conditions the left front reversible emergency tensioning retractor and right front reversible emergency tensioning retractor are activated. The "seat belt slack" on the driver or passenger seat is drawn in until the belt makes firm contact with the passenger's body, provided that the corresponding driver/passenger seat belts are buckled.
Front passenger seat conditioning
The driver seat does not have any PRE-SAFE adjustment (conditioning).
Seat positioning serves to move the occupants to a position that will lessen the effects of an accident. Conventional restraint systems can act ideally in this position.
The left front/right front reversible emergency tensioning retractors send the conditioning request of the front passenger seat cyclically over CAN-C, the central gateway control unit, the Controller Area Network bus Class B (interior) (CAN-B) to the front passenger front seat adjustment control unit with memory.
Only when an unfavorable seat position is given and the front passenger seat is recognized as occupied (CAN-C signal from restraint systems control unit), is an adjustment made to the seats for the duration of the PRE-SAFE situation.
The following settings must be normalized:
- Height, longitudinal inclination adjustment
- Backrest
This automatic adjustment of the front passenger seat can be interrupted at any time by actuating the passenger-side seat adjustment switch.
A memory reset regulation of the passenger-side seat does not take place after the PRE-SAFE situation is over.
The PRE-SAFE function for the passenger-side seat can be switched off using the diagnosis in the front passenger front seat adjustment control unit with memory.
Vehicle skidding (lateral dynamics)
If vehicle skidding is recognized, then the previously described functions are executed. Additionally the side windows and tilting/sliding roof (SHD) are closed to within a gap of 50 mm.
The closing process for the side windows can be interrupted by pressing any of the switches. If, with an active automatic closing of the windows, a request is received, the process is not interrupted, i.e. the windows are fully closed.
The closing process of the tilting/sliding roof can be interrupted at any given time by pressing the roof switch (N70s1). If the overhead control panel control unit continues to recognize the transmitted "PRE-SAFE message", the tilting/sliding roof closing process is continued with. A memory reset regulation of the tilting/sliding roof does not take place after the PRE-SAFE situation is over.
The anti-pinch protection is operative during the closing process and if activated will cause the drive to be reversed.
End PRE-SAFE function
The following adjustments are interrupted by the respective control units, insofar as they have not reached their PRE-SAFE positions:
- The left front reversible emergency tensioning retractor and right front reversible emergency tensioning retractor only release the tensioned belts from the driver and front passenger, once the vehicle acceleration (irrespective of direction) drops below a value of 0.3 g and PRE-SAFE longitudinal or lateral dynamics are no longer present. If the initial release process is not successful, a second one is initiated.
- Adjustment of passenger-side seat
- Power window and tilting/sliding roof run to the end of their automatic sequence, i.e. they move to their PRE-SAFE position even after the PRE-SAFE situation is over.
Error message
Faults are stored in the left front reversible emergency tensioning retractor and right front reversible emergency tensioning retractor and displayed in the instrument cluster.
| Supplemental restraint system (SRS), function | Model 251.1 with code 494 USA version | GF91.60-P-0002RT | |
| Model 251 except code 494 USA version Model 251 except code 498 Japanese version |
GF91.60-P-0002RTE | ||
| Reversible belt emergency tensioning retractor, component description | GF91.60-P-4050RT |