GF91.40-P-0001LE PRE-SAFE function 23.6.10 MODEL 216.3, 221.0 /1 as of model year 2009
/YoM 08
Function requirements, general PRE-SAFE, general
Circuit 15 ON The PRE-SAFE system is activated in critical driving states, i.e. in a
potential accident situation. The goal is to create the most favorable Vehicle speed v > 30 km/h
conditions possible for the occupants during the expected accident Engine running (circuit 61 ON)
by activating the functions before the actual impact. The data of the ESP control unit (N47-5) (without model The status of circuit 15 is sent by the EZS control unit (N73) to
221.095/195) or the regenerative braking system control unit (N30/6) the interior CAN (CAN B).
(model 221.095/195) is evaluated for triggering the PRE-SAFE The "Engine running" status is made available by the CDI control
functions. unit (N3/9) (with diesel engine) or the ME-SFI [ME] control unit
(N3/10) (with gasoline engine) via chassis CAN (CAN E).
---The PRE-SAFE function consists of the following subfunctions:
Function sequence for seat belt slack reduction (on model Function sequence for closing all door windows
221) Function sequence for automatic closing of tilting/sliding
Function sequence for registering of activation criteria roof (SHD) (with model 221 with code (414) Power glass tilting/sliding sunroof or with model 216)
Function sequence when Electronic Stability Program (ESP)
Function sequence for adjusting the seat contour is disabled
(with code (409) Left/right front multicontour seats or with Function sequence for reversible emergency tensioning
code (432) Left and right dynamic multicontour seat or on retraction for driver and front passenger (with model 221)
model 221 with code (406) Rear multicontour seats) Function sequence for adjusting front passenger seat
Function sequence for display of fault messages Function sequence for adjusting individual rear seats
Function sequence for ending the PRE-SAFE functions (with model 221 with code (223) Rear bench seat with
electrically adjustable outer seats with PRE-SAFE
positioning function for outer seats and outer head
---restraints)
---Additional function requirements for seat belt slack reduction
( in the case of model 221) The left front reversible emergency tensioning retractor (A76) and right front reversible emergency tensioning retractor (A76/1) now Function in instrument cluster (A1) activated
tension the belt strap at a speed of v = 50 mm/s (
PRE-SAFE has not been activated 10 %) until the
seat belt slack is reduced. The belt force generated here increases at the end of the pretensioning process to F = 20 N (
Function sequence for seat belt slack reduction (on model 221) 20 %). Once
the belt force has been reached, the seat belt is pretensioned for The seat belt slack reduction function reduces the existing seat belt
another t = 400 ms. Following expiration of this time, the seat belt slack once the seat belt is fastened.
slack reduction function is ended. The insertion of the seat belt tab into the belt buckle triggers the seat
belt slack reduction function. This is recognized via the driver seat belt buckle and seat belt reminder warning switch (S68/1) and the front passenger seat belt buckle and seat belt reminder warning switch (S68/2) by the restraint systems control unit (N2/7).
---Function sequence for registering of activation criteria The radar sensors control unit (SGR) (N62/1) (with code (233)
The recording of the activation criteria function comprises the DISTRONIC PLUS up to 31.8.10) or video and radar sensor system
following subfunctions: control unit (N62/2) (with code (233) DISTRONIC PLUS as of
D Function sequence for registering the PRE-SAFE 1.9.10) initiates braking of the vehicle (PRE-SAFE brake) because of
longitudinal dynamics information from the DTR controller unit (A89).
D Function sequence for registering the PRE-SAFE lateral
dynamics On vehicles with code (238) Active Lane Keeping Assist, the video
Function sequence for recording the vehicle surroundings and radar sensor system control unit initiates a corrective brake
(with code (233) DISTRONIC PLUS) intervention if necessary if a collision hazard is detected during lane change.
Function sequence for registering the PRE-SAFE longitudinal
dynamics Detailed information on this can be found in the function
- Emergency stop: description "DISTRONIC PLUS" or the function description "Active
The driver fully depresses the brake pedal hard. Lane Keeping Assist".
- Secondary brake application as a result of a panic reaction: The driver fully depresses the brake pedal down to the maximum pedal travel.
- Braking of the vehicle by PRE-SAFE brake (with code (233) DISTRONIC PLUS)
- Brake intervention by the Active Lane Keeping Assist
(with code (233) DISTRONIC PLUS and Code (238) Active Lane Keeping Assist)
---Function sequence for determining the PRE-SAFE lateral dynamics
Driving situations in which danger of possible collisions may occur:
- Excessive oversteer: - Intersection situations:
A large rear axle slip angle that can no longer be stabilized by Vehicle unexpectedly drives into an intersection
the ESP. - Cut-in situations:
- Excessive understeer: Vehicle cuts in directly in front of the driver
A large front axle slip angle pending for an extended period, - Cornering:
which can no longer be stabilized by the ESP An unexpected obstacle appears while in the curve
- Critical steering movement:
Driver steering movement which is probably due to a startled
The vehicle distance from a recognized object (vehicle, obstacle) is reaction and which may lead to instability of the vehicle.
determined by the inner left radar sensor, front bumper (A86/1b2) Activation does not take place until speeds of
and the inner right radar sensor, front bumper (A86/1b3) at current v > 140 km/h have been reached. The activation characteristics
closing speed. become more sensitive with increasing speeds
The radar sensors (short range sensors) recognize obstacles within a short range up to s = 30 m and at an angle up to 140°.
Function sequence for recording the vehicle surroundings (with code (233) DISTRONIC PLUS)
In order to prevent a possible collision with vehicles or obstacles, radar sensors are installed in the front bumper.
---
---Obstacles can hereby be detected early and reversible occupant The signals of the short range front radar sensors are sent via protection measures (e.g. occupant immobilization) can be initiated. sensor CAN (CAN S) to the radar sensors control unit or the video The data for determining the severity of the collision and the time of and radar sensor system control unit and evaluated.
the collision are read in by the radar sensors control unit or video
and radar sensor system control unit and provided to the restraint Function sequence when the ESP is switched off
systems control unit. The triggering threshold for the PRE-SAFE functions is raised if the
Accordingly, the restraint systems control unit can then trigger the ESP was shut off manually via the ESP OFF switch (S6/2s11)
corresponding restraint equipment earlier. (model 211 up to 31.05.09) in the cockpit switch group (S6/2). The
signals from the cockpit switch group are read in by the upper The sequence of PRE-SAFE functions is coordinated by the PRE- control panel control unit (N72/1) via instrument panel LIN (LIN 1). SAFE master. This is integrated into the ESP control unit or into the The upper control panel control unit transmits the signals via the regenerative braking system control unit. If the PRE-SAFE master interior CAN to the central gateway control unit (N93). The central recognizes a critical driving situation, is activates the following gateway control unit sends the signals via chassis CAN to the ESP
actuators: control unit or to the regenerative braking system control unit.
- Reversible belt tensioning for driver and front passenger (on model 221)
- Adjusting front passenger seat - Closing all door windows
- Closing the tilting/sliding roof (SHD)
(on model 221 with code (414) Power glass tilting/sliding roof or on model 216)
---
---The reaction of the reversible emergency tensioning retractors The ESP OFF switch is discontinued on model 221 as of
varies depending on the recognized PRE-SAFE situation: 31.5.09. The ESP can be switched off via the left multifunction
- in the event of a longitudinal dynamics situation, the belt is steering wheel button group (S110) on model 221 as of 1.6.09. The
tensioned as quickly as possible (within approx. t = 120 ms) to a message is shown in the multifunction display (A1p13) of the
defined power level. instrument cluster.
- in the event of a lateral dynamics situation, the tensioning time is parameterizable
Function sequence for reversible emergency tensioning retraction for driver and front passenger (with model 221)
At the end of the tensioning request, the belt is released again. The left front reversible emergency tensioning retractor and the right
The reversible emergency tensioning retractors are activated only if front reversible emergency tensioning retractor reduce the existing
the vehicle speed is v > 30 km/h and the latches of the seat belts are seat belt slack in dangerous situations. Thus, the occupants are
inserted into the seat belt buckles. secured in position in the seats at an early point in time in order to
prevent displacement. This is recognized via the driver seat belt buckle and seat belt
reminder warning switch and the front passenger seat belt buckle The occupants are therefore held in a favorable seat position in the
and seat belt reminder warning switch by the restraint systems event of an accident, allowing the conventional restraint systems to
control unit. have their optimum protective effect.
The restraint systems control unit sends the status of the seat belt The reversible emergency tensioning retractors receive the signal for
buckles via chassis CAN to the ESP control unit or to the emergency tensioning retraction via chassis CAN from the ESP
regenerative braking system control unit. control unit or the regenerative braking system control unit.
---
---If the speed drops below v = 30 km/h during a PRE-SAFE situation, The status of the front passenger seat belt buckle and seat belt all PRE-SAFE functions remain active until the speed has dropped reminder warning switch is transmitted by the restraint systems
below control unit via the chassis CAN to the central gateway control unit.
v = 3 km/h. This routes the status via the interior CAN to the right front seat
control unit (N32/2).
Depending on the current setting, the following adjustments can be
Additional function requirements for adjusting the front
made by the right front seat control unit:
passenger seat
- Seat fore/aft position Normalized front passenger seat
- by the right front seat fore/aft adjustment motor (M28/1) Front passenger seat occupied
- by the right front backrest angle adjustment motor (M28/5) - Seat cushion inclination
Function sequence for adjusting front passenger seat
- by the right front seat cushion inclination motor (M28/9) Adjustment of the front passenger seat is used to move the front
- Seat height passenger into a favorable position in the event of an imminent
- by the right front seat height adjustment motor (M28/10) impact.
The front passenger seat is adjusted according to whether the front passenger is strapped in or not strapped in.
---
---The automatic adjustment of the front passenger seat can be Additional function requirements for adjustment of individual
interrupted at any time by operating the right front seat operation rear seats
switch group (S23). (on model 221 with code (223) Rear bench seat with electrically
If a PRE-SAFE situation continues to be present, the front adjustable outer seats with PRE-SAFE positioning function for
passenger seat is adjusted again via PRE-SAFE after the manual outer seats and outer head restraints)
adjustment has been completed. Seat adjustment normalized
Rear seats set to an unfavorable position The adjustment process lasts until:
- The target area is reached (front passenger seat in ideal Function sequence for adjustment of individual rear seats
position) (on model 221 with code (223) Rear bench seat with electrically
- An impact occurs adjustable outer seats with PRE-SAFE positioning function for
- The PRE-SAFE situation ends outer seats and outer head restraints)
Rear seat adjustment is used to move the rear occupants into a The front passenger seat does not automatically return to the favorable position in the event of an imminent impact.
position before the PRE-SAFE situation, but rather has to be In this position, the restraint equipment can provide the best adjusted via the right front seat operation switch group as protective effect possible. The adjustment occurs according to
necessary. whether the rear occupants are strapped in or not strapped in.
---
---The status of the left rear seat belt buckle switch (S68/11) and the Seat adjustment if occupants are buckled up right rear seat belt buckle switch (S68/12) is forwarded by the rear Dependent upon how the rear seats are set, the: SAM control unit with fuse and relay module (N10/2) via the interior - inclination of the head restraint is adjusted CAN to the central gateway control unit, and from there via the - backrest is adjusted
interior CAN to the rear seat control unit (N25/6). - seat cushion inclination is adjusted
Depending on the current setting, the following adjustments can be
made by the rear seat control unit: Seat adjustment if occupants are not buckled up
- Head restraint inclination The system moves the seat into a position that is suitable for
- by the left rear head restraint inclination adjustment motor situations that are unfavorable with regard to safety technology. (M18/15) and the right rear head restraint inclination
adjustment motor (M18/16)
The adjustment process lasts until:
- Seat cushion inclination - The target area is reached (rear seats in ideal position)
- by the left rear seat cushion inclination adjustment motor - An impact occurs (M18/19) and the right rear seat cushion inclination adjustment
- The PRE-SAFE situation ends motor (M18/20)
- Seat fore/aft position
- by the left rear seat fore/aft adjustment motor (M18/17) and the The PRE-SAFE function of the rear seats can be switched off using the diagnostic tester.
right rear seat fore/aft adjustment motor (M18/18)
---Function sequence for closing all door windows The anti-pinch protection is active when the windows are closed via PRE-SAFE. If required, the closing process is reversed.
The following control units receive the signal for the ESP control unit or the regenerative braking system control unit to close the windows
from the central gateway control unit via interior CAN: The closing process can be stopped at any time by a manual
- Left door control unit (N69/1) (model 216) request from the following controls for the respective window:
- Left front door control unit (N69/1) (model 221) - Driver power window outside mirror and trunk lid switch group (S20/1)
- Right door control unit (N69/2) (model 216)
- Front passenger power window switch (S21/2) - Right front door control unit (N69/2) (model 221)
- Left rear power window switch (S21/3) (model 221 without code - Left rear door control unit (N69/3) (model 221)
(297) Roller sun blinds in rear doors, without code (413) - Right rear door control unit (N69/4) (model 221)
Panoramic glass sunroof with top sliding sunroof, without code The windows are closed by the left front power window motor
(540) Electric rear window roller blind) (M10/3), right front power window motor (M10/4), left rear power
- Right rear power window switch (S21/4) (model 221 without code window motor (M10/5) and the right rear power window motor
(297) Roller sun blinds in rear doors, without code (413) (M10/6) to a gap of
Panoramic glass sunroof with top sliding sunroof, without code s = 50 mm, to ensure that in the event of any subsequent impact the
(540) Electric rear window roller blind) smoke particles generated by the pyrotechnical restraint equipment
are then extracted.
---
--- Power window/roller blind switch group, left rear door (S21/21) Function sequence for automatic closing of tilting/sliding roof
(model 221 with code (297) Roller sun blinds in rear doors, with (on model 221 with code (414) Power glass tilting/sliding roof or
code (413) Panoramic glass sunroof with top sliding sunroof or on model 216)
Closing the tilting/sliding roof via PRE-SAFE is intended to prevent - Power window/roller blind switch group, right rear door (S21/22) objects from penetrating the vehicle interior and stop the occupants'
(model 221 with code (297) Roller sun blinds in rear doors, with body parts (such as arms) from protruding from the vehicle if an code (413) Panoramic glass sunroof with top sliding sunroof or accident occurs.
with code (540) Electric rear window roller blind) The overhead control panel control unit (N70) receives the request of the ESP control unit or the regenerative braking system control unit from the central gateway control unit via interior CAN and If closing is activated via PRE-SAFE during an automatic lowering
triggers the closure of the tilting/sliding roof. process, the automatic lowering process is aborted and closing is
carried out via PRE-SAFE. The tilting/sliding roof is closed leaving a gap of s = 50 mm in order
to ensure that, in the event of a possible subsequent impact, smoke Once the PRE-SAFE situation has ended, the windows must be
particles generated by the pyrotechnical restraint systems can manually moved back into the desired position.
escape.
Closing can be aborted at any time by manually operating the roof
---switch (N70s1).
---The anti-pinch protection is active when the tilting/sliding roof is Function sequence for adjustment of the seat contour
being closed. If required, the closing process is reversed. (with code (409) Left/right front multicontour seats or with code
If closing is activated via PRE-SAFE during a manual adjustment, (432) Left and right dynamic multicontour seat or on model 221
the manual adjustment request is completed first and then closing with code (406) Rear multicontour seats)
via PRE-SAFE. The purpose of inflating the side inserts in the seats is to centrally
secure the occupants in position in the seats. In this position, the restraint equipment can provide the best protective effect possible. If closing is activated via PRE-SAFE during an automatic process,
the automatic process is aborted and closing is carried out via PRE- The following control units receive the signal of the ESP control unit
SAFE. or the regenerative braking system control unit to close the windows
from the central gateway control unit via interior CAN: With code (409) Left/right front multicontour seats: Once the PRE-SAFE situation has ended, the tilting/sliding roof must
- Left front multicontour backrest control unit (N32/15) be manually moved back into the desired position.
- Right front multicontour backrest control unit (N32/16) The PRE-SAFE function of the tilting/sliding roof can be switched
With code (432) Left and right dynamic multicontour seat: off using the diagnostic tester.
- Left front dynamic seat control unit (N32/19) - Right front dynamic seat control unit (N32/22)
---For model 221 with code (406) Rear multicontour seats: Function sequence for ending the PRE-SAFE functions
- Left rear multicontour backrest control unit (N32/20) PRE-SAFE is deactivated as soon as a PRE-SAFE longitudinal - Right rear multicontour backrest control unit (N32/21) dynamics situation or lateral dynamics situation is no longer present.
The ESP control unit or the regenerative braking system control unit sends a signal to switch off the PRE-SAFE functions via chassis The seat contour is adjusted until the PRE-SAFE specified pressure
CAN. is reached or until the end of the PRE-SAFE situation.
The signal is transmitted to the control units involved through the Once the PRE-SAFE situation has ended, the filling status of the
central gateway control unit via the interior CAN. side inserts is returned to the respective initial status it had before
PRE-SAFE was activated. The adjustment of the front passenger seat and the individual rear
seats is canceled if the PRE-SAFE position has not yet been reached.
The adjustment of the seat contour can be aborted at any time via a manual adjustment or by means of a memory request.
Closing of the windows and the tilting/sliding roof is not aborted. The automatic closing function continues until the PRE-SAFE position
Function sequence for display of fault messages
has been reached. If a fault is detected in the reversible emergency tensioning
retractors, this is indicated on the multifunction display of the
The reversible emergency tensioning retraction is released as soon instrument cluster. Faults of other components that are part of
PRE-as the vehicle acceleration hPRE-as dropped below a value of SAFE are not displayed as PRE-SAFE faults.
a = 0.3 g.
---In the event of an impact that is detected by the restraint systems The reversible emergency tensioning retractors are equipped
control unit, all adjustments are stopped immediately. with a mechanical acceleration sensor, which locks the belt
extension in the event of any vehicle acceleration of a > 0.3 g. For this reason, the belt may remain mechanically locked even when the reversible tensioning retraction has been completed.
PRE-SAFE, location of components Model 216 GF91.40-P-0001-01LA
Model 221 GF91.40-P-0001-01LE
Electrical function schematic, pre-safe Model 216 PE91.40-P-2051-97CAB
Model 221 PE91.40-P-2051-97SAB
Model 221.095/195 GF54.30-P-6000LEH
Component description for front reversible A76, A76/1 GF91.40-P-4020LE
emergency tensioning retractor Model 221
DTR controller unit, component description On model 216 up to 31.8.10 with engine 156, GF30.30-P-3210LE
273, 275 and code (233) DISTRONIC PLUS Model 221 up to 31.8.10 with engine 156, 272, 273, 275, 642, 629 and code (233) DISTRONIC PLUS
On model 216 as of 1.6.09 up to 31.8.10 GF30.30-P-3210LEB
with engine 156, 273, 275 and code (233) Distronic Plus Model 221 as of 1.6.09 up to 31.8.10 with engine 156, 272, 273, 275, 642, 629 and code (233) Distronic Plus
On model 216.3 as of 1.9.10 GF30.30-P-3210LED
With code (233) DISTRONIC PLUS Model 221 (except 221.095/195) as of 1.9.10 with code (233) DISTRONIC PLUS or
Component description for restraint systems N2/7 GF91.60-P-4048LE
control unit
Component description for rear SAM control N10/2 GF54.21-P-6030LE
unit with fuse and relay module
Rear seats control unit, component N25/6 GF91.29-P-5250LE
description Model 221 with code (223) Rear bench seat
with electrically adjustable outer seats with PRE-SAFE positioning function for outer seats and outer head restraints
Component description for regenerative N30/6 GF42.22-P-1100LEH
braking system control unit On model 221.095/195
Right front seat control unit, component N32/2 GF91.29-P-5240LE
description
Multicontour seat control unit (MCS), N32/15, N32/16 GF91.25-P-5201LE
component description With code (409) Left/right multicontour seats
N32/20, N32/21 GF91.25-P-5201LEA
Model 221 with code (406) Rear multicontour seat
Dynamic seat control unit, component N32/19, N32/22 GF91.25-P-5202LE
description On model 221 up to 31.5.09 with code (432)
Left and right dynamic multicontour seat, on model 216 with code (432) Left and right dynamic multicontour seat
Component description for ESP control unit N47-5 GF42.45-P-5118LE
Model 216.3, model 221 (except 221.095/195)
Component description for radar sensors N62/1 GF30.30-P-3301LE
control unit Up to 31.8.10 with code (233) DISTRONIC
PLUS
Video and radar sensor system control unit, N62/2 GF30.30-P-3304LE
component description As of 1.9.10
with code (233) DISTRONIC PLUS, with code (238) Active Lane Keeping Assist
Component description for left door control N69/1 GF72.29-P-4124LA
unit Model 216
Component description for left front door N69/1 GF72.29-P-4141LE
control unit Model 221
Component description for right door control N69/2 GF72.29-P-4128LA
unit Model 216
Component description for right front door N69/2 GF72.29-P-4142LE
control unit Model 221
Rear door control unit, component description N69/3, N69/4 GF72.29-P-6020LE
Model 221
Component description for overhead control N70 GF82.20-P-5216LE
panel control unit
Upper control panel control unit, component N72/1 GF54.21-P-6040LE
description
EZS control unit, component description N73 GF80.57-P-6003LE
Component description for central gateway N93 GF54.21-P-4170LE
control unit
Component description for Weight Sensing N110 GF91.60-P-4069LAU
System (WSS) control unit Model 216 with code (494) USA version,
Model 221 with code (494) USA version As of 1.9.08
