Part 1

GF30.30-P-0006CE DISTRONIC PLUS Incl. BAS PLUS and PRE-SAFE Brake, Function
MODEL 204.0 /2
- with CODE (233) Distronic Plus
- as of model year 2012
/YoM 11 facelift
MODEL 204.3
- with CODE (233) Distronic Plus





A1 Instrument cluster
A1e59 DISTRONIC warning lamp
A1h1 Warning buzzer
A1p13 Multifunction display
A2 Radio (with code (523) MB Audio
20 radio or code (510) Audio 20 with CD changer)
A2/30 Navigation module (with code (509) Navigation box)
A2/30-1 Cradle for navigation module (with code (508) Navigation box preinstallation or code (509) Navigation box)
A7/3 Traction system hydraulic unit

A28/11 Multifunction antenna
A40/3 COMAND controller unit (with code (512) COMAND APS incl. DVD changer or code (527) COMAND APS with single DVD drive (with navigation))
A89 DISTRONIC electric controller unit
B24/15 Yaw rate, lateral and longitudinal acceleration sensor
B29/2 DISTRONIC sensor (DTR) / left front bumper
B29/3 DISTRONIC sensor (DTR) / right front bumper
B37 Accelerator pedal sensor
L6/1 Left front axle rpm sensor
L6/2 Right front axle rpm sensor
L6/3 Left rear axle rpm sensor
L6/4 Right rear axle rpm sensor
N3/9 CDI control unit (with diesel engine)
N3/10 ME-SFI [ME] control unit (with gasoline engine)
N10/1 Front SAM control unit with fuse and relay module
N15/3 Electronic transmission control control unit (with transmission 722.6)
N30/4 Electronic Stability Program control unit
N49 Steering angle sensor
N62/2 Video and radar sensor system control unit
N80 Steering column tube module control unit
S4 Combination switch
S9/1 Stop lamp switch
S12 Parking brake indicator switch
S40/4 Cruise control lever
S40/4r1 DISTRONIC control
S40/4v1 SPEEDTRONIC light-emitting diode (without code (494) USA version)
Y3/8n4 Fully integrated transmission control control unit (with transmission 722.9)

CAN A Telematics CAN
CAN B Interior CAN
CAN C Drive train CAN
CAN E Chassis CAN
CAN H Vehicle dynamics CAN
CAN S Sensor CAN

Function requirements, general
^ No undervoltage or overvoltage
^ "ADTR_AVL" (Advanced DISTRONIC PLUS) programmed in the front SAM control unit
^ Engine running or drivetrain operational
^ Radar sensor system not switched off
^ Long range radar soiling and function test completed successfully
^ Electronic Stability Program (ESP(R)) not passively switched (except model 204.077/277/377)
^ ESP(R) not switched into "SPORT HANDLING MODE" (for model 204.077/277/377)
^ No active ESP(R) intervention recognized
^ Vehicle not in a reverse or sliding movement
^ Gear range "D" engaged
^ Parking brake not operated
^ Standstill coordinator, release awarded (driver door/driver belt buckle and front passenger door closed)
The standstill coordinator function is described in detail in the separate description "Adaptive Brake (ABR)".

The status engine running or drivetrain operational is transmitted by the CDI control unit or the ME-SFI [ME] control unit via chassis CAN.
The status of the gear range is transmitted by the transmission control unit (for transmission 722) via the drive train CAN, the CDI control unit or the ME-SFI [ME] control unit via chassis CAN. The status of the parking brake is registered via the parking brake indicator switch. This is read directly by the front SAM control unit and transmitted via the chassis CAN.
The status of the ESP is transmitted by the ESP control unit via the chassis CAN.

DISTRONIC PLUS incl. BAS PLUS and PRE-SAFE brake, general points
The units and values given in the following text for the speed must be assigned to the possible national versions. The details in "miles per hour (mph)" refer to vehicles with a miles indicator.

The DISTRONIC PLUS function automatically regulates the speed and the distance to the vehicle driving immediately ahead in a vehicle speed range of v = 0 to 200 km/h and from v = 200 to 0 km/h (v = 0 to 120 mph and from v = 120 to 0 mph) according to the request from the driver.

The PRE-SAFE brake function permanently determines the potential danger of a head-to-tail crash occurring and initiates appropriate measures to warn of an impending collision and possibly to mitigate the effects of a collision.

Furthermore, there is a distance warning function contained therein which advises the driver about a vehicle driving immediately ahead which is too close. An optical and acoustic warning is issued before any possible collisions with vehicles or stationary obstacles on the vehicle's own lane.

If the driver reacts to the warning with emergency braking, he is supported by the function Brake Assist System (BAS) PLUS. The required brake servo assistance is calculated dependent on the situation.
This means that the brakes are automatically applied as intensively as required (max. approx. a = 10 m/s2).
In this way a threatened collision can be prevented or, at least, the consequences of the collision are mitigated.
If the driver does not react to the warning, the PRE-SAFE brake feature decelerates the vehicle by automatically actuating the brakes to prevent a possible collision or reduce the possible consequences.

Controlling takes place by the video and radar sensor system control unit. The video and radar sensor system control unit intervenes actively in the engine timing as well as in the brake system to realize the functions. The optical and acoustic warnings are emitted over the IC.

The video and radar sensor system control unit is connected over the following Control Area Network (CAN) to the vehicle electronics:
- Chassis CAN
- Vehicle dynamics CAN
- Sensor CAN

The PRE-SAFE brake function also supports the PRE-SAFE safety concept.
The PRE-SAFE function is described in the separate function description "PRE-SAFE Function".

The following partial functions of the DISTRONIC PLUS function are described in the separate function description "CC (TPM) function":
- Cruise control
- Variable SPEEDTRONIC (without code (494) USA version)
- Permanent limiter

The following graphical representations show the principle of operation of the functions DISTRONIC PLUS incl. BAS PLUS and PRE-SAFE brake.





Detection area of the radar sensor system

1 Systems vehicle, equipped with DISTRONIC PLUS
2 The vehicle driving immediately ahead (target object) is detected by the long range radar sensors (77 GHz frequency range)
3 The vehicle driving immediately ahead in traffic is detected by the medium-range radar within the long range radar sensors (77 GHz frequency range)
4 The stationary vehicle on the driving lane edge is detected by the short range radar sensors (24 GHz frequency range) (in countries without approval for the 24-GHz radar system, registration of stationary objects is not possible)

A Long range radar (up to s = 200 m, for a detection angle of about ( = 18°)
B Mid-range detection area of the long range radar (up to s = 60 m, for a detection angle of about ( = 60°)
C Short range radar (up to s = 30 m, for a detection angle of about ( = 80°)





Illustration of the principle of the functions BAS PLUS and PRE-SAFE brake, shown on model 221

A1e59 DISTRONIC warning lamp

1 Systems vehicle, equipped with BAS PLUS and PRE-SAFE brake
19 Stationary or a significantly slower vehicle in own lane
t1 Approx. t = 2.6 s before a possible accident; output of visual and acoustic warning messages, activation of the BAS PLUS function
t2 About t = 1.6 s before a possible accident; automatic partial braking by the PRE-SAFE brake function; possibly also evasive maneuvers by the driver or hazard braking are performed by the driver and supported by BAS PLUS function
t3 Approx. t = 0.6 s until accident, automatic emergency braking by PRE-SAFE brake function

The functions DISTRONIC PLUS, BAS PLUS and PRE-SAFE brake require the following input factors implementation of the functions distance control and distance warning :
- Object recognition in the long range
- Object recognition in the short range

Object recognition in the long range by means of the long range radar sensors (77 GHz long range radar):
The long range radar operating in the 77 GHz frequency range is integrated in the DISTRONIC electric controller unit (A89) and covers the front area of the vehicle for a length of s = 60 m up to s = 200 m for a detection angle of measured angle = 18°. The range s = 0 m to s = 60 m in front of the vehicle is detected for an angle of measured angle = 60°.
The DISTRONIC controller unit performs a soiling and function test to ensure proper operation after each engine start.

The function test requires an object in the detection range of the long range radar which is used as a reference value for the function test by the DISTRONIC control unit. The DISTRONIC PLUS cannot be activated if a malfunction is established or if there are no objects (for the function test) in the detection range of the long range radar. The DISTRONIC PLUS controller unit communicates via the vehicle dynamics CAN with the video and radar sensor system control unit.

The long range radar operates according to the pulse Doppler effect which allows the distances and speeds of individual objects (e.g. vehicles) to be measured independently of each other.

Object recognition in the short range by means of the short range radar sensors (24 GHz short range radar):

The short range radar sensor system is not installed in countries in which no approval exists for the 24-GHz radar system.

The short range radar sensors work in the front bumper in the 24 GHz frequency range for a maximum range of s = 30 m and are integrated in the following components:
- DISTRONIC sensor (DTR) / left front bumper
- DISTRONIC sensor (DTR) / right front bumper

The recording angle of the short range radar sensors is a maximum of measured angle = 130°. Within a detection angle of measured angle = 60° the angle is determined precisely and objects are still detected up to an angle of measured angle = 130°.
The front bumper DISTRONIC (DTR) sensors communicate via the sensor CAN with the video and radar sensor system control unit.

Automatic shutoff of short-range radar sensor system:
In the vicinity of radio-astronomy stations the radar sensor system is switched off automatically due to the legal requirements on the 24-GHz-Radar system (short range radar).

For vehicles with code (494) USA version the automatic shutoff of the short range radar sensors is discontinued.

The DISTRONIC PLUS incl. BAS PLUS and PRE-SAFE brake is therefore not functional in these areas.
The restricted areas around radio astronomy stations are stored in the video and radar sensor system control unit.
The navigation system for the COMAND controller unit or the radio in combination with the navigation module adapted via the telematics CAN receives the global positioning system (GPS) signals via the combined antenna. The radio or the COMAND controller permanent transmits the current GPS coordinates via the interior CAN to the front SAM control unit.

The front SAM control unit transmits the GPS signals via the chassis CAN to the video and radar sensor system control unit.

This reacts by transmitting an appropriate request to shutoff the short range radar sensors to the following components via the sensor CAN:
- DISTRONIC sensor (DTR) / left front bumper
- DISTRONIC sensor (DTR) / right front bumper

When the vehicle leaves the protected area, the short range radar sensor system is switched on again automatically.
For an activated DISTRONIC PLUS function the message "DISTRONIC PLUS available again " is issued.

When the vehicle leaves the protected area, the short range radar sensor system is switched on again automatically.
For an activated DISTRONIC PLUS function the message "DISTRONIC PLUS available again " is issued.

The driver has the option to switch the short range radar sensor system off and on manually over the "Vehicle settings" menu in the IC. If one seeks to manually switch on the short range radar sensors within a protected area, the message "Radar sensor system switched off automatically" is displayed in the multifunction display.





Schematic display of automatic radar sensor system shutoff

A1p13 Multifunction display
A2 Radio (with code (523) MB Audio
20 radio or code (510) Audio 20 with CD changer)
A28/11 Multifunction antenna
A2/30 Navigation module (for code (508) Navigation box preinstallation or code (509) Navigation box)
A2/30-1 Cradle for navigation module (with code (508) Navigation box preinstallation or code (509) Navigation box)

A40/3 COMAND controller unit (with code (512) COMAND APS incl. DVD changer or code (527) COMAND APS with single DVD drive (with navigation))
B29/2 DISTRONIC sensor (DTR) / left front bumper
B29/3 DISTRONIC sensor (DTR) / right front bumper
N62/2 Video and radar sensor system control unit

GPS Global Positioning System
RAS Radio astronomy station
SB Restricted area for a radio astronomy station

Operation:
Operation of the DISTRONIC PLUS function takes place over the cruise control lever. The steering column tube module control unit directly reads in control signals of the CC lever and transmits these via the chassis CAN to the video and radar sensor system control unit.





Design of the cruise control lever

S40/4 Cruise control lever
S40/4r1 DISTRONIC control
S40/4s1 Resume from memory switch
S40/4s2 Decelerate and fix switch in place
S40/4s3 Accelerate and fix switch in place
S40/4s4 OFF switch
S40/4s6 SPEEDTRONIC switch (with code (494) USA version)
S40/4v1 SPEEDTRONIC light-emitting diode (without code (494) USA version)





Operation over the cruise control lever, Vehicles without code (494) USA version

5a Accelerate and set in 1 km/h increments
5b Accelerate and set in 10 km/h increments
6a Decelerate and set in 1 km/h increments
6b Decelerate and set in 10 km/h increments
7 Switching on of the DISTRONIC PLUS (acknowledgment for automatic driving off) or variable SPEEDTRONIC (if no target speed is stored, the current speed is set as the target speed)
8 Increasing the specified distance for the DISTRONIC PLUS
9 Reducing the specified distance for the DISTRONIC PLUS
10 Selection option between DISTRONIC PLUS and variable SPEEDTRONIC
11 SPEEDTRONIC light-emitting diode (lights up in the position variable SPEEDTRONIC)
12 Switching off the DISTRONIC PLUS or variable SPEEDTRONIC





Operation over the cruise control lever, Vehicles with code (494) USA version:

13a Accelerate and set in 1 mph/h increments
13b Accelerate and set in 5 mph/h increments
14a Decelerate and set in 1 mph/h increments
14b Decelerate and set in 5 mph/h increments
15 Switching on of the DISTRONIC PLUS (acknowledgment for automatic driving off) or switching on of cruise control (if no target speed is stored, the current speed is set as the target speed)
16 Increasing the specified distance for the DISTRONIC PLUS
17 Reducing the specified distance for the DISTRONIC PLUS
18 Switching off of DISTRONIC PLUS

The video and radar sensor system control unit evaluates the input factors and transmits the appropriate requests for controlling of the functions DISTRONIC PLUS, BAS PLUS and PRE-SAFE brake via the following CAN:
- Chassis CAN
- Vehicle dynamics CAN
- Sensor CAN

The DISTRONIC PLUS function includes the following partial functions:
^ Function sequence for DISTRONIC PLUS
^ Function sequence for PRE-SAFE brake and BAS PLUS

Additional function requirements for DISTRONIC PLUS
^ DISTRONIC PLUS in menu "Driver assist" on the IC switched on
^ Target object (vehicle moving immediately ahead) detected
^ CC lever in the DISTRONIC PLUS position (SPEEDTRONIC LED Off)
If the SPEEDTRONIC LED (except code (494) USA version) lights up, the DISTRONIC PLUS function is deactivated and variable SPEEDTRONIC function (except code (494) USA version) is programmed.

Function sequence for DISTRONIC PLUS
The description of the DISTRONIC PLUS function takes place, as an example, in the following chronological sequence:
- Activate DISTRONIC PLUS and drive off automatically
- Automatic distance control
- Change of driving lane (overtaking)
- Automatic speed control
- Going back into a lane/regulation by the person in front
- automatic stopping

The sequence can vary depending on the driver requests and the current traffic situation.

The DISTRONIC PLUS function can only be activated when stationary if there was also a stationary vehicle detected over the radar sensor system. This displayed by the distance graphic in the multifunction display. The vehicle is now ready to follow the vehicle driving immediately ahead.

To do this the video and radar sensor system control unit transmits appropriate information via the chassis CAN to the instrument cluster.

For every actuation of the CC lever the interval to the vehicle moving directly ahead is displayed in the multifunction display for t = 5 s. Through selection of the operating level "DISTRONIC PLUS" in the menu "Assistance" the distance graphic is shown permanently.

Display of the distance graphic can be switched on or off independently of the activity of the automatic distance control. The distance to the vehicle driving immediately ahead can be switched on or off via the DISTRONIC control in seven stages between about. t = 1.0 and 2.0 s. If a distance of t = 2.0 s is set for example, the vehicle driving immediately ahead will be followed at a temporal distance of t = 2.0 s. This physical gap increases with increasing speed.