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Distronic Plus, Function - GF30.30-P-3300GN

MODEL 166 as of model year 2016 with CODE 239 (DISTRONIC PLUS) 

MODEL 292 as of model year 2016 with CODE 239 (DISTRONIC PLUS) 

IMPORTANT The nomenclature for "DISTRONIC PLUS" has changed, the designation is "Distance Pilot DISTRONIC" as of YoM J1717/2. The nomenclature change is not taken into account in this documentation.

Block diagram, except model 166.063 

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Block diagram, model 166.063 

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Function requirements, general 

IMPORTANT Detailed information about the standstill control is available in a separate document.

Distronic PLUS, general 

DISTRONIC PLUS automatically regulates the speed and distance to the vehicle in front based on the driver's inputs in a vehicle speed range of v = 0 to 200 km/h and v = 200 to 0 km/h. The control is realized via the DISTRONIC electric controller unit.

The DISTRONIC PLUS is extended by the function COLLISION PREVENTION ASSIST PLUS. It includes the functions distance warning, adaptive Brake Assist system and autonomous partial braking (vehicle speed up to v = 200 km/h). If the driver does not react to warning tones in an accident-critical situation, the DISTRONIC electric controller unit initiates an autonomous partial braking.

The following subfunctions of DISTRONIC PLUS are described in a separate document:

The following graphic represents the mode of function of the DISTRONIC PLUS:

Detection range of DISTRONIC electric controller unit, shown on model 292 

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Operation of the DISTRONIC PLUS takes place over the cruise control lever.

Design of the cruise control lever 

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IMPORTANT If the LED SPEEDTRONIC lights up, the DISTRONIC PLUS is deactivated and the function variable SPEEDTRONIC programmed. The steering column tube module control unit actuates the SPEEDTRONIC LED directly.

IMPORTANT The distance to the vehicle driving immediately ahead is displayed in the multifunction display for t = 5 s after actuation of the CC lever. 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 in front can be set via the DISTRONIC control in seven stages between approx. 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.

DISTRONIC electric controller unit evaluates the following input factors: 

DISTRONIC PLUS is switched on via the CRUISE CONTROL lever: The steering column tube module control unit directly reads in the switch position of the CC lever and sends it to the DISTRONIC electric controller unit via chassis CAN 1.

Operating condition for engine/drivetrain:

Parking brake status:

The status of the parking brake (activated or deactivated) is sent by the electric parking brake control unit via chassis CAN 1 to the DISTRONIC electric controller unit.

Engaged gear range:

Driver request via the cruise control lever: 

The driver request over the CC lever are directly read in by the steering column tube module control unit. The steering column tube module control unit sends the control signals of the CRUISE CONTROL lever via the chassis CAN 1 to the DISTRONIC electric controller unit.

Vehicle speed/acceleration:

The vehicle speed is calculated from the wheel speed. The acceleration is defined over the increase in rotational speed. The Electronic Stability Program control unit transmits the wheel speed signals via chassis CAN 1 to the DISTRONIC electric controller unit.

Object recognition:

The DISTRONIC electric controller unit monitors the traffic area in front of the vehicle up to a distance of s = 200 m in a corridor of ∠ = 12°.

Engine drive torque:

Braking torque:

The Electronic Stability Program control unit transmits information about the currently set braking torque via chassis CAN 1 to the DISTRONIC electric controller unit.

Acceleration/yaw rate:

The acceleration/yaw rate sensor for lateral and longitudinal acceleration records the acceleration/yaw rate and sends this via the vehicle dynamics CAN, Electronic Stability Program control unit and chassis CAN 1 to the DISTRONIC electric controller unit.

IMPORTANT For reasons of safety and comfort the maximum (positive) acceleration of the automatic distance control is limited to approx. a = 2.5 m/s2 . It operates anti-proportional to the vehicle speed, which means that the positive and negative accelerations reduce with increasing speed.

Wheel angle

The Electronic Stability Program control unit sends the position of the wheels via the chassis CAN 1 to the DISTRONIC electric controller unit. Steering wheel angle:

The steering wheel angle sensor detects/records the steering wheel angle. The steering column tube module control unit directly reads in the signals from the steering wheel angle sensor and sends information about the steering wheel angle via chassis CAN 1 to the DISTRONIC electric controller unit.

Driver request to overtake (sets the turn signals on the combination switch)

The steering column tube module control unit directly reads in the switch position of the combination switch and sends it to the DISTRONIC electric controller unit via chassis CAN 1.

Brake pedal position:

The Electronic Stability Program control unit transmits the status of the brake pedal via chassis CAN 1 to the DISTRONIC electric controller unit.

Accelerator pedal position:

The DISTRONIC electric controller unit issues the following initial parameters (requests): 

Raise/reduce engine torque:

The DISTRONIC electric controller unit transmits the request "Increase engine torque" or "Decrease engine torque" via chassis CAN 1 to the Electronic Stability Program control unit. The Electronic Stability Program control unit evaluates this request as well as further driving dynamics requests and sends them in accordance with their relevance

The CDI control unit or the ME-SFI [ME] control unit implements this request.

Engage targeted gear (downshift or upshift):

The DISTRONIC electric controller unit transmits the request "Engage targeted gear" via chassis CAN 1 to the Electronic Stability Program control unit. The Electronic Stability Program control unit evaluates this request as well as further driving dynamics requests and sends them in accordance with their relevance

This request is to be understood as a shift recommendation.

Downshifting or upshifting of the A/T takes place autonomously itself by the fully integrated transmission control unit, dependent on the current operating condition.

Object information:

Raise/reduce braking torque:

The DISTRONIC electric controller unit transmits the request "Increase braking torque" or "Decrease braking torque" via chassis CAN 1 to the Electronic Stability Program control unit. The Electronic Stability Program control unit reacts by directly actuating the traction system hydraulic unit, which reacts by increasing or decreasing the braking torque according to the brake torque.

IMPORTANT The Electronic Stability Program control unit decides in relation to additional variables such as the current charge level of the high voltage on-board electrical system whether and to what intensity the deceleration occurs through regenerative braking or through the service brake.

Emit warning tones, system or warning messages The DISTRONIC electric controller unit sends the requests to output acoustic warnings and system and warning messages via the chassis CAN 1, electronic ignition lock control unit and chassis CAN 2 to the instrument cluster. The corresponding system and warning messages are output via the multifunction display, while acoustic warnings are emitted through the warning buzzer.

Function sequence for DISTRONIC PLUS 

The description of the DISTRONIC PLUS function takes place, as an example, in the following chronological sequence:

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

Activate DISTRONIC PLUS and drive off automatically 

The following options are available for activating DISTRONIC PLUS:

Drive off from standstill without vehicle in detection range:

If there is no stationary/moving vehicle in the detection range of the DISTRONIC electric controller unit, DISTRONIC PLUS is active but automatic start-off does not take place. To initiate the driving-off procedure, the driver must either briefly press the accelerator pedal or call the last selected set speed (set speed 30 km/h) via the "Resume from memory" switch on the cruise control lever.

Automated drive-off from standstill with vehicle in detection range: If a stationary or moving vehicle is in the detection range of the DISTRONIC electric controller unit, the vehicle then follows, insofar as the driver briefly operated the accelerator pedal beforehand or the driver pressed the resume from memory switch on the cruise control lever to call up the last configured set speed.

IMPORTANT For vehicles at a standstill a specified distance limit exists beyond which a stationary vehicle is no longer displayed.

Technical implementation 

The DISTRONIC electric controller unit receives or sends the following information or requests for this:

Input factors:

Initial parameters:

Automatic distance control 

The automatic distance control can only be activated while driving (v < 20 km/h (mph)) if a vehicle driving immediately ahead was detected. If the vehicle driving immediately ahead brakes or accelerates, the DISTRONIC PLUS can initiate the following measures for deceleration or acceleration of the vehicle:

The brake application takes place by means of hydraulic pressure controlling in the wheel brake cylinder by the traction system hydraulic unit according to the current vehicle status. To do this the Electronic Stability Program control unit assesses various variables such as the required braking torque.

The driver must press on the brake pedal is sees that the instigated measures are not adequate to avoid any possible collision. If the vehicle driving immediately ahead accelerates again, the engine torque is increased and the vehicle also accelerates. The increase in engine torque is dependent on the ascent or the descent involved, among other things.

The driver furthermore has the option of operating the accelerator pedal to accelerate the vehicle (e. g. when overtaking). The multifunction display shows 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 and the "DISTRONIC passive" message goes off.

IMPORTANT The automatic distance control is also active if the acceleration request from the driver is lower than the automatic distance control request.

IMPORTANT If the vehicle driving in front leaves the detection range of the DISTRONIC electric controller unit, the automatic distance control is deactivated at v < 20 km/h.

Technical implementation 

The DISTRONIC electric controller unit receives or sends the following information or requests for this:

Input factors:

Initial parameters:

Change of driving lane (overtaking) 

For an overtaking maneuver above a speed of v = 60 km/h the vehicle is also automatically accelerated. To do this the driver must initiate the overtaking maneuver by setting the turn signal. Where the automatic distance control is activated, the DISTRONIC electric controller unit recognizes the intention of the driver to overtake and accelerates the vehicle while taking account of the distance to the vehicle driving in front.

When approaching a slowly moving vehicle and therefore an active automatic intervention by the brake system, this is then canceled insofar as the driver initiates the overtaking procedure by operating the turn signal. If required, the vehicle is additionally accelerated.

After the overtaking maneuver the vehicle accelerates to the set speed (automatic speed control), insofar as no other vehicle driving in front was detected as a target object. If a vehicle driving immediately ahead is subsequently detected as a target object the automatic speed control function changes over again into the automatic distance control function.

Initial parameters:

The overtaking maneuver is broken off in the following situations:

Technical implementation 

The DISTRONIC electric controller unit receives or sends the following information or requests for this:

Input factors:

Automatic speed control 

If the vehicle is in active distance control and the vehicle driving immediately ahead accelerates above v = 200 km/h or removes itself from the detection area of the DISTRONIC electric controller unit, the automatic distance control switches over into the automatic speed control.

IMPORTANT Detailed information about the automatic speed control is available in a separate document.

Technical implementation 

The DISTRONIC electric controller unit receives or sends the following information or requests for this:

Input factors:

Initial parameters:

Going back into a lane/person in the front regulation 

If the vehicle driving immediately ahead turns off and there is another vehicle in front, the system only switches over to the new target vehicle if it is moving. The system does not operate for stationary objects unless a preceding vehicle is tracked to a standstill. If while driving a vehicle turns in front within the safe distance to the vehicle driving immediately ahead, the distance to this new vehicle is regulated. If the vehicle is in automatic speed control and a vehicle tuns onto the lane driven in this vehicle is registered as the vehicle driving immediately ahead. If the distance to the swinging-in vehicle lies below the value that was preselected, DISTRONIC PLUS decelerates the vehicle. If the requested braking power is not sufficient, a visual warning and warning tones are output and the driver must press the brake pedal.

DISTRONIC PLUS is thereby deactivated. This process is signaled to the driver through output of a message "DISTRONIC PLUS OFF" in the multifunction display of the instrument cluster. The driver can subsequently reactivate the DISTRONIC PLUS.

Technical implementation 

The DISTRONIC electric controller unit receives or sends the following information or requests for this:

Input factors:

Initial parameters:

Distance warning 

DISTRONIC PLUS warns the driver visually and acoustically in the vehicle speed range between v = 7 and 250 km/h or the maximum design speed about moving obstacles in his/her lane. DISTRONIC PLUS differentiates here between a static (without code 460 (Canada version) and without code 494 (USA version)) and a collision-critical distance warning.

Static distance warning (without code 460 (Canada version) and without code 494 (USA version)):

Output of the static distance warning takes place purely optically. If the distance to the vehicle in front falls below t = 0.8 s in moving traffic and remains at this critical distance for t > 3 s (e. g. at a speed of v = 100 km/h, distance approx. s = 22.2 m), the DISTRONIC electric controller unit transmits the warning output request via the suspension CAN 1, electronic ignition lock control unit and suspension CAN 2 to the instrument cluster. The instrument cluster reacts by actuating the DISTRONIC warning lamp.

Collision critical distance warning:

Output of the collision-critical distance warning takes place optically and acoustically.

If an obstacle in the detection range of the DISTRONIC electric controller unit is classified as accident-critical (collision within t < 2.6 s), the DISTRONIC electric controller unit transmits the warning output request via the suspension CAN 1, electronic ignition lock control unit and suspension CAN 2 to the instrument cluster that then activates the DISTRONIC warning lamp and directly actuates the warning buzzer. Take-back of the warning only occurs if the situation has been defused.

In the case of stationary obstacles, a warning is only output in the vehicle speed range between v = 7 and approx. 70 km/h.

Optical warning messages in instrument cluster 

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This is displayed inversely in the multifunction display, i.e. the distance warning readiness display is hidden in the case of an active distance warning function. If the distance warning function is deactivated, the distance warning readiness indicator and the "OFF" lettering are shown.

IMPORTANT The distance warning is basically active for an active DISTRONIC PLUS. If DISTRONIC PLUS is deactivated, Collision Prevention Assist Plus, which also contains a distance warning system, can be separately activated in the "Collision Prevention Assist Plus" menu on the instrument cluster.

Adaptive brake assistant 

If the driver reacts in a critical situation with emergency braking, he is supported by the Adaptive BAS. The DISTRONIC electric controller unit calculates the necessary brake force amplification in order to avoid any collision or at least to mitigate its consequences. Adaptive Brake Assist supports the driver in a vehicle speed range between v = 7 and 250 km/h for a maximum full-stop braking to vehicles in front and in a vehicle speed range between v = 7 and approx. 70 km/h to stationary obstacles.

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

The DISTRONIC electric controller unit takes the current distance and the closing speed to the obstacle into account to permanently calculate the required brake force. If there is no actuation or the intensity of actuation of the brake pedal by the driver considerably decreases, the brake boost on the driver braking is reduced and the Adaptive Brake Assist System is also deactivated. The Brake Assist System will also be deactivated if the driver presses the accelerator pedal.

Additional function requirements for autonomous partial braking 

Autonomous partial braking 

If the driver fails to react in an accident-critical situation to the warning, the DISTRONIC electric controller unit initiates autonomous partial braking and reduction in engine torque. The DISTRONIC electric controller unit calculates the braking torque required (maximum deceleration approx. a = 6 m/s2 ) taking the following variables into account:

The DISTRONIC electric controller unit sends the appropriate request to increase the braking torque and to reduce the engine torque via the chassis CAN 1 to the Electronic Stability Program control unit. The Electronic Stability Program control unit evaluates the incoming requests, directly actuates the traction system hydraulic unit and sends the request to reduce engine torque

If the driver then reacts to the autonomous partial braking and brakes, the Adaptive Brake Assist System provides support for the best possible utilization of the braking distance to the obstacle.

IMPORTANT If a collision is unavoidable, occupant protection measures are taken in addition to intervention by the brake system. Detailed information on the topic of occupant protection is available in a separate document.

Automated Stop Vehicle 

For an active DISTRONIC PLUS the vehicle will follow the vehicle driving immediately ahead to standstill. The deceleration here is due to regenerative braking or the service brake. The service brake also secures a stationary vehicle against rolling away.

After a defined time period the electric parking brake is also activated (standstill control safety strategy).

IMPORTANT Securing the vehicle using the DISTRONIC PLUS function (standstill control) does not replace securing the vehicle for parking.

Technical implementation 

The DISTRONIC electric controller unit receives or sends the following information or requests for this:

Input factors:

Initial parameters:

The following traffic situations show the limits of DISTRONIC PLUS:

Obstacles and stationary vehicles 

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The DISTRONIC PLUS does not brake for obstacles or stationary vehicles which were not previously registered 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.

Curves, curved entrances and exits 

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The DISTRONIC PLUS can only provides limited detection of vehicles in curves. One's own vehicle can then brake unexpectedly or late.

Vehicles moving across in front of one's own vehicle 

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DISTRONIC PLUS 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).

Offset driving style 

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DISTRONIC PLUS may not be able to detect vehicles driving displaced to one side. The distance to the vehicle in front becomes too small.

Lane change by other vehicles 

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The DISTRONIC PLUS does not yet detect the vehicle moving into the lane. The distance to the vehicle moving into the lane becomes too small.

Narrow vehicles 

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DISTRONIC PLUS does not detect the vehicle in front at the edge of the carriageway because of its narrow width. The distance to the vehicle in front becomes too small.

  Electrical function schematic for DISTRONIC PLUS   PE30.30-P-2053-97NBA 
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