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DISTRONIC PLUS incl. BAS PLUS and PRE-SAFE brake, function - GF30.30-P-0006LE

MODEL 216.3 with CODE (233) Distronic Plus as of model year 2011 / YoM 10 model refinement package 

MODEL 221.0 /1 (except 221.095 /195) with CODE (233) Distronic Plus as of model year 2011 / YoM 10 

Function requirements, general 

IMPORTANT The CDI control unit (N3/9) (for a diesel engine) or the ME-SFI [ME] control unit (N3/10) (for a gasoline engine) sends the signal "engine running" or "drivetrain operational" via the chassis CAN (CAN E).

The status of the gear range is transmitted by the EGS control unit (N15/3) (for transmission 722.6) or the fully integrated transmission control unit (VGS) (Y3/8n4) (for transmission 722.9) via the drive train CAN (CAN C), CDI control unit or ME-SFI [ME] control unit and chassis CAN.

The electric parking brake controller unit (A13) transmits the status of the parking brake via the front end CAN (CAN G). The status of the ESP is transmitted by the ESP control unit (N47-5) via the chassis CAN.

Apart from the listed function requirements there is constant checking on safety grounds whether the driver is present in the vehicle. The driver recognition takes place by the standstill coordinator, which is implemented in the ESP control unit.

The following vehicle components are monitored to do this:

IMPORTANT The detailed function of the standstill coordinator should be taken from the separate description "Adaptive Brake (ABR)".

DISTRONIC PLUS incl. BAS PLUS and PRE-SAFE brake, general points 

IMPORTANT Speed data:

The specified assemblies and values for the speed are assigned to the national versions. The details in "miles per hour (mph)" refer to vehicles with code (494) USA version.

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

Furthermore a distance warning function is included which informs the driver about an excessively short distance to the vehicle moving immediately ahead. There is an optical and acoustic warning issued before possible collisions with vehicles or stationary obstacles on its own lane.

If the driver reacts to the collision critical warning with emergency braking he is supported in this by the function BAS PLUS. The brake servo assistance required for this is calculated according to the situation.

This means that the brakes remain applied as intensively as required (max. approx. a = 10 m/s2 ).

In this way a threatening collision is prevented or at least the severity of the accident is reduced.

If the driver does not react to the warning, the PRE-SAFE feature secures the vehicle by automatically actuating the brakes to prevent a possible collision or to reduce the possible consequences.

To do this the PRE-SAFE brake function permanently determines potential danger concerning a head-to-tail crash occurring and initiates appropriate measures to warn of an accident-critical situation and to mitigate the effects of a collision.

Controlling is undertaken by the video and radar sensor system control unit (N62/2). The video and radar sensor system control unit actively intervenes in the engine timing and in the brake system to realize the functions. The optical and acoustic warnings are issued by the IC (A1).

IMPORTANT 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".

IMPORTANT Further partial functions of the DISTRONIC PLUS function are described in the separate function description "CC (TPM) function":

Operation:

Operation of the DISTRONIC PLUS function takes place over the CC [TPM] push button (S40/4).

Structure of the CC [TPM] push button (S40/4) 

Fig 1: Identifying CC (TPM) Push Button Operation
G07641050Courtesy of MERCEDES-BENZ USA

Operation over the CC [TPM] push button, Vehicles without code (494) USA version 

Fig 2: Operation Diagram Of CC (TPM) Push Button - Vehicles Without Code (494)
G07641051Courtesy of MERCEDES-BENZ USA

Operation over the CC [TPM] push button, Vehicles with code (494) USA version 

Fig 3: Operation Diagram Of CC (TPM) Push Button - Vehicles With Code (494)
G07641052Courtesy of MERCEDES-BENZ USA

Detection area of the radar sensor system 

Fig 4: Detection Area Of Radar Sensor System
G07641053Courtesy of MERCEDES-BENZ USA

The DISTRONIC PLUS function requires the following input factors to implement the functions distance control and distance warning:

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

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

The short range radar sensor system in the front bumper operates in the 24 GHz frequency range for a maximum range of s = 30 m:

The recording angle of the short range radar sensors is a maximum of ∠ = 130°. A precise angle can be determined within a detection zone of ∠ = 60° and just the existence of objects can be detected at angles up to ∠ = 130°. The radar sensors communicate via the sensor CAN (CAN S) with the video and radar sensor system control unit.

Due to legal requirements on the 24 GHz radar system (short range radar), the short range radar sensor system is automatically switched off in certain protected areas around radio astronomy stations.

The protected areas of the radio astronomy stations are stored in the form of Global Positioning System (GPS) coordinates in the video and radar sensor system control unit. The NAV of the COMAND controller unit (A40/3) permanently transmits the current global positioning system coordinates via the backbone CAN (CAN F), central gateway control unit and chassis CAN to the video and radar sensor system control unit, which reacts by switching off the short range radar sensor system.

For an active DISTRONIC PLUS function the message "Radar sensor system automatically switched off, see operating instructions" is displayed in the multifunction display (A1p13) of the IC.

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.

IMPORTANT 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 again 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 

Fig 5: Schematic Display Of Automatic Radar Sensor System Shutoff
G07641054Courtesy of MERCEDES-BENZ USA

Object recognition in the long range by means of the long range radar sensors (77 GHz long range radar):

The long range radar operates in the 77 GHz frequency range and is integrated into the DTR controller unit (A89).

The traffic in the area s = 60 to 200 m in front of the vehicle is detected for a detection angle of ∠ = 18°.

The traffic in the area s = 0 to 60 m in front of the vehicle is detected for a detection angle of ∠ = 60°.

The DTR controller unit performs a soiling and function test to secure its perfect functioning 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 DTR control unit. The DISTRONIC PLUS function 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 DTR controller unit communicates via the vehicle dynamics CAN (CAN H) with the video and radar sensor system control unit.

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

Apart from information from the radar sensor system the following information is also taken into account:

Intensity of the acceleration in the longitudinal direction

The requested maximum positive acceleration of the automatic distance control is limited on safety and comfort grounds to about a = 2.5 m/s2 . The negative acceleration is limited to about 40% (about a = 4 m/s2 ) of the maximum possible brake power.

The maximum positive acceleration requested for automatic distance control is antiproportional to the vehicle speed which means that limitation of the positive and negative acceleration reduces with increasing speed.

The positive and negative acceleration of the vehicle is detected by the yaw rate sensor for lateral and longitudinal acceleration (B24/15) and transmitted via the vehicle dynamics CAN.

Direction of travel and vehicle speed:

In order to determine the direction of travel of the vehicle, the ESP control unit directly reads in signals from the following components:

IMPORTANT The wheel rotation direction is determined dependent on the drive variants. Information about this is contained in the separate description "Adaptive Brake (ABR) function".

The Electronic Stability Program control unit sends the information on the wheel speeds and directions of wheel rotation via the chassis CAN to the video and radar sensor system control unit. The video and radar sensor system control unit uses the information to calculate the vehicle speed and defines the direction of travel.

Rotation angle:

The current rotation angle is detected by the steering wheel angle sensor (N49) the signals from which are read in directly by the steering column tube module control unit (N80). The steering column tube module reads in the steering angle sensor data and sends the data via the chassis CAN to the video and radar sensor system control unit.

The functions DISTRONIC PLUS incl. BAS PLUS and PRE-SAFE brake include the following partial functions:

Function sequence for automatic speed control 

The automatic speed control (CC) function allows the driver to establish a speed within the vehicle speed range of v = 30 to v = 200 km/h (v = 20 to v = 120 mph) which the vehicle then automatically maintains.

The function is activated using the CC [TPM] push button. The specified speed can be set in v = 1 km/h or v = 10 km/h (1 mph or 5 mph) steps:

IMPORTANT Vehicles without code (494) USA version

The possibly active variable SPEEDTRONIC is deactivated and the LED, variable speed limiter goes out.

Actuation of the LED takes place by means of the switchover logic integrated in the CC [TPM] push button.

The status of the LED is read in directly by the steering column tube module and transmits this via the chassis CAN to the video and radar sensor system control unit.

1 km/h or 1 mph steps:

The accelerate and set switch must be actuated upwards to the actuation point or the decelerate and set switch must be actuated downwards to the actuation point.

10 km/h or 5 mph steps:

The accelerate and set switch must be actuated upwards beyond the actuation point or the decelerate and set switch must be actuated downwards beyond the actuation point.

If the respective switch is held at or beyond the actuation point then the set speed increases automatically by an interval of t = 0.6 s.

The selected vehicle speed range is displayed through lighting up of the segment ring around the electronic speedometer (A1p8). If the automatic speed control function is activated, the vehicle accelerates automatic up to the specified speed.

IMPORTANT When driving down hills there is also braking in order to maintain the specified speed.

Additional function requirements for automatic distance control 

Function sequence for automatic distance control 

The distance to the vehicle driving immediately ahead can be set in seven stages over the DTR distance potentiometer between about t = 1.0 and 2.0 s.

IMPORTANT The temporal information about the specified distance is related to the distance the vehicle travels at a certain speed. The distance to the vehicle driving immediately ahead should at 50% of the displayed speed value (an example: v = 100 km/h requires a minimum distance of s = 50 m)

The video and radar sensor system control unit evaluates the input factors of the long range and short range radar sensors and detects the vehicle moving directly ahead as a target object.

The distance to the vehicle moving directly ahead is displayed in the multifunction display for t = 5 s.

While taking account of the programmed setting on the CC [TPM] push button, the video and radar sensor system control unit regulates the distance to the vehicle moving directly ahead.

Vehicles without code (494) USA version

The active function automatic distance control is signaled to the driver through lighting up of the LED, variable speed limiter.

If the vehicle moving directly ahead accelerates to more than v = 200 km/h (v = 120 mph) or removes itself from the detection range of the radar sensor system, the function automatic distance control switches over to the function automatic speed control. The vehicle reacts by being regulated at the specified speed set by the driver.

IMPORTANT Through selection of the operating level "DISTRONIC PLUS" in the menu "Assistant" in the IC, the distance graphic is shown permanently. Display of the distance graphic can be activated or deactivated independently of the activity of the function automatic distance control.

View of the instrument cluster for an activated DISTRONIC PLUS and vehicle immediately ahead 

Fig 6: View Of Instrument Cluster For Activated Distronic Plus
G07641055Courtesy of MERCEDES-BENZ USA

The partial function automatic distance control takes place within the system limits depending on the input factors and includes the following subfunctions:

Function sequence for automatic acceleration and braking 

The video and radar sensor system control unit reads in the following input factors from the respective components to regulate the self-sufficient acceleration:

The DTR controller unit evaluates data for the detected target object, processes this and transmits the respective information via the vehicle dynamics CAN to the video and radar sensor system control unit.

The video and radar sensor system control unit processes the input factors and transmits the request to increase or reduce the engine torque via the chassis CAN to the Electronic Stability Program control unit.

The Electronic Stability Program control unit evaluates this information as well as further requests and passes these on, according to their relevance, via the chassis CAN to the CDI control unit or the ME-SFI [ME] control unit. The CDI control unit or the ME-SFI [ME] control unit implements the request for an increase or decrease of the engine torque appropriately.

IMPORTANT The driver also has the possibility of using the accelerator pedal to intervene manually in acceleration of the vehicle (e. g. to perform an overtaking maneuver).

For this purpose, the CDI control unit or the ME-SFI [ME] control unit reads in the accelerator pedal sensor signals (B37) directly and sends them to the video and radar sensor system control unit via the chassis CAN.

automatic acceleration is put out of action for as long a the driver accelerates the vehicle using the accelerator pedal.

This process is optically displayed in the multifunction display with the message "DISTRONIC passive".

If the automatic distance control requires a higher acceleration than the driver prescribes, the driver request is overlaid by the request for automatic distance control.

If reduction of the engine torque is not sufficient to achieve the required distance, the video and radar sensor system control unit sends a request to apply the brakes to the Electronic Stability

Program control unit via the chassis CAN. The Electronic Stability

Program control unit implements the request to brake through modulated actuation of the traction system hydraulic unit (A7/3).

IMPORTANT Furthermore, the driver has the opportunity over the brake pedal to manually intervene in deceleration of the vehicle.

Function requirements for automatic driving off (for stop-and-go traffic) 

IMPORTANT The position of the brake pedal is detected by the brake light switch (S9/1). The Electronic Stability Program control unit directly reads in the status of the brake light switch and transmits this via the chassis CAN to the video and radar sensor system control unit, which evaluates it appropriately.

Automatic start-off function sequence (with Stop-and-Go traffic) 

Regulated driving off by means of the DISTRONIC PLUS function allows automatic start-off and stopping of the vehicle in stop-and-go traffic.

The driver must acknowledge the driving off process by actuating (pulling on) the switch "Resume from memory". The status of the "Resume from memory" switch is transmitted by the steering column tube module via the chassis CAN to the video and radar sensor system control unit.

The video and radar sensor system control unit receives this, evaluates it and transmits the request to increase the engine torque to the Electronic Stability Program control unit.

The Electronic Stability Program control unit evaluates this information as well as further requests and passes it on, according to their relevance, via the chassis CAN to the CDI control unit or the ME-SFI [ME] control unit.

the CDI control unit or the ME-SFI [ME] control unit implements this request appropriately and the vehicle starts off automatically.

Important function notes in special driving situations:

The special considerations arising from the following traffic situations should also be observed:

Obstacles and stationary vehicles

The DISTRONIC PLUS function does not brake for obstacles or stationary vehicles which were not previously detected as the target object.

If, for example, the detected vehicle turns off and there is an obstacle or stationary vehicles behind it, no automatic intervention by the brake system occurs.

Fig 7: Detection Range For Obstacles And Stationary Vehicles
G07300324Courtesy of MERCEDES-BENZ USA

Curves, curved entrances and exits:

The DISTRONIC PLUS function can only provides limited detection of vehicles in curves. The systems vehicle can then brake unexpectedly or late.

Fig 8: Detection Range For Curves, Curved Entrances And Exits
G07300325Courtesy of MERCEDES-BENZ USA

Vehicles moving across in front of one's own vehicle:

DISTRONIC PLUS function may detect vehicles in cross traffic by mistake.

For an activated distance control the vehicle can start off unintended, (e g. at a traffic light with cross-traffic).

Fig 9: Detection Range For Vehicles Moving Across In Front Of One's Own Vehicle
G07300326Courtesy of MERCEDES-BENZ USA

Function sequence for PRE-SAFE brake and BAS PLUS 

The PRE-SAFE brake function assesses the traffic situation in front of the vehicle.

In a hazard situation within the following speed ranges, the vehicle is decelerated automatically by the PRE-SAFE brake function or the emergency braking maneuver by the driver is supported by the BAS PLUS function:

In the case of stationary obstacles the PRE-SAFE brake function or the BAS PLUS function is only activated if the vehicle's own vehicle speed is a maximum of v = 72 km/h (v = 45 mph).

The following example situation leads to activation of the function PRE-SAFE brake and also BAS PLUS function if necessary:

If a stationary object is detected in the lane by both the short and long range radar sensor systems (the lane is determined by the steering angle and vehicle speed, etc.), the PRE-SAFE brake function and BAS PLUS function, if necessary, are activated. The following illustration shows the example situation described as well as the chronological sequence of the functions PRE-SAFE brake and BAS PLUS.

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

Fig 10: BAS Plus And Pre-Safe Brake Function Diagram
G07641059Courtesy of MERCEDES-BENZ USA

The PRE-SAFE brake function also includes a proximity warning system to warn the driver visually and acoustically about moving or stationary obstacles in his lane. The distance warning takes place in the following vehicle speed ranges:

In this case, differentiation is made between a static and a collision critical distance warning.

Static distance warning:

The static distance warning is triggered by the video and radar sensor system control unit when the time interval between the system vehicle and vehicle in front is less than t = 0.8 s (e. g. in moving traffic). To do this the video and radar sensor system control unit transmits the request for an optical warning via the chassis CAN, central gateway control unit and backbone CAN to the IC, which reacts by actuating the DTR warning lamp.

Collision critical distance warning:

If a moving obstacle within the detection range of the radar sensor system is classified as accident-critical (a collision will occur within t < 2.6 s) the video and radar sensor system control unit transmits the requests for an optical and acoustic warning via the chassis CAN, central gateway control unit and backbone CAN to the IC, which reacts by actuating the DTR warning lamp and the warning buzzer (A1h1) (intermittent tone).

The request present as a warning output is switched off automatically when the situation is defused and cannot be deactivated during active regulation.

IMPORTANT The AWS can be separately and independently activated by the automatic distance control function in the menu "PRE-SAFE brake" of the IC.

The distance warning is basically active for an active DISTRONIC PLUS function. If the function DISTRONIC PLUS is deactivated, actuation of the DTR warning lamp takes place by the function PRE-SAFE brake.

Visual warning message in instrument cluster when a safe distance is not maintained 

Fig 11: Identifying DTR Warning Lamp And Distance Warning Readiness Indicator
G07641060Courtesy of MERCEDES-BENZ USA

The video and radar sensor system control unit will initiate partial braking if the driver does not react to the acoustic and optical warning signals.

To do this the video and radar sensor system control unit calculates a braking torque while taking account of the driving dynamics input factors, which are transmitted via the vehicle dynamics CAN to the ESP control unit.

The ESP control unit implements the request over the traction system hydraulic unit and brakes the vehicle according requirements. If the driver then reacts with an emergency braking maneuver, the BAS PLUS function provides support for optimum utilization of the braking distance to the object.

IMPORTANT The hazard braking is defined over the actuation speed and the actuation strength with which the brake pedal is actuated.

To do this the video and radar sensor system control unit also uses data from the radar sensor system and calculates the necessary brake servo assistance while taking account of the current clearance and the closing speed to the obstacle.

The video and radar sensor system control unit transmits the appropriate requests via vehicle dynamics CAN to the ESP control unit which actuates the hydraulic brake pressure over the traction system hydraulic unit.

If there is no actuation or the intensity of actuation of the brake pedal by the driver reduces, the brake servo assistance on the driver braking is reduces and the function BAS PLUS deactivated.

The function BAS PLUS will also be deactivated if the driver presses on the accelerator pedal. Operation of the accelerator pedal is detected by the accelerator pedal sensor (B37).

The CDI control unit or the ME-SFI [ME] control unit directly reads in the accelerator pedal sensor and transmits this via the chassis CAN to the video and radar sensor system control unit.

If the driver does not react to the partial braking and if the calculation is made by the video and radar sensor system control unit that a collision with the obstacle is unavoidable, the video and radar sensor system control unit instigates emergency braking for t = 1 s and thereby reduces the possible consequences of the accident.

IMPORTANT On vehicles with code (299) PRE-SAFE, a full braking operation is not actuated when a passenger is present in the front passenger seat and his seat belt is not fastened.

REFER TO SYSTEM WIRING DIAGRAMS Electrical function schematic for DISTRONIC PLUS incl. BAS PLUS and PRE-SAFE brake Model 216 PE30.30-P-2055-97CAA
Model 221 PE30.30-P-2055-97SAA
  Component description for instrument cluster A1
Model 216, 221 (except 221.095/195)		 GF54.30-P-6000LE
Model 221.095/195 GF54.30-P-6000LEH
  Component description for electric parking brake controller unit A13 GF42.20-P-5000LE
  Component description for COMAND controller unit A40/3
With code (527) COMAND APS with single DVD drive (with navigation system)		 GF82.85-P-3136LE
With code (530) COMAND APS USA (with navigation system) GF82.85-P-3136LEU
  Component description for bumper radar sensors A86/1b2, A86/1b3 GF30.30-P-3302LEB 
  Component description for DTR controller unit A89 GF30.30-P-3210LED 
  Component description for yaw rate sensor for lateral and longitudinal acceleration B24/15 GF42.45-P-4810LE
  Component description for CDI control unit N3/9
Model 221 with engine 629		 GF07.16-P-6000OA
Model 221 with engine 642.8 GF07.16-P-6000OHS
Model 221 with engine 642.9 GF07.16-P-6000OHL
Model 221 with engine 651 GF07.16-P-6000OLS
  Component description for ME-SFI [ME] control unit N3/10
For model 221 with engine 272 (except 272.974)		 GF07.61-P-6000MIS
Model 221 with engine 272.974 GF07.61-P-6000MEH
With engine 273 GF07.61-P-6000MLS
With engine 275 GF07.61-P-6000MOS
Model 221 with engine 276 GF07.61-P-6000MMB
With engine 157, 278. GF07.61-P-6000MMC
  Component description for electronic transmission control unit N15/3
Transmission 722.6		 GF27.60-P-5164ACS
  Component description for ESP control unit N47-5, A7/3
Model 216, 221 (except model 221.095/195)		 GF42.45-P-5118LE
  Component description for video and radar sensor system control unit N62/2 GF30.30-P-3304LE 
  Component description for steering column tube module N80 GF54.21-P-6050LE
  Component description for central gateway control unit N93 GF54.21-P-4170LE
  Component description for fully integrated transmission control unit Y3/8n4
For transmission 722.9 (except code 722.931/950)		 GF27.60-P-5165AHS
With transmission 722.931 GF27.60-P-5165AHT
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