DISTRONIC Plus, Function - GF30.30-P-3300RDM
Model 172.4
as of model year 2016
with code 239 (Active Distance Assist DISTRONIC)
Shown on model 172.4 as of 01.03.2016
Shown on model 172.4 up to 29.02.2016
Function requirements general
- No undervoltage or overvoltage
- The DISTRONIC electric controller unit is correctly calibrated and coded
The DISTRONIC PLUS is coded in the electronic ignition lock control unit (N73)
- DISTRONIC PLUS switched on via the CRUISE CONTROL lever
- Engine running or drivetrain operational
- Parking brake not operated
- Gear range "D" engaged
- Vehicle is not in backward movement
- Soiling and function test of DISTRONIC electric controller unit completed successfully
The DISTRONIC electric controller unit performs a soiling and function test to secure its perfect functioning after each engine start. This assumes an object is in the detection range which can be used as a reference value DISTRONIC PLUS cannot be activated if a malfunction is detected or if there is no object (for the function test) in the detection range of the DISTRONIC electric controller unit.
- No active intervention recognized by the Electronic Stability Program (ESP)®)
- Standstill control enable issued (driver door/driver belt buckle and front passenger door closed)
Detailed information about the standstill control is available in a separate document.
DISTRONIC PLUS general
DISTRONIC PLUS automatically regulates the speed and the distance to the vehicle directly ahead in line with the driver's specification in a vehicle speed range of v = 0 to 200 km/h and v = 200 to 0 km/h. This is controlled by 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 in an accident-critical situation to the acoustic warning the DISTRONIC electric controller unit initiates an autonomous partial braking.
If the DISTRONIC PLUS is switched off the situation directly in front of the vehicle is still detected and evaluated. In dangerous situations warnings are given as described above or there is autonomous braking. Detailed information is available in a separate document.
The adaptive cruise control electric controller unit actively intervenes in the engine management the transmission control and controlling of the brake system to implement the DISTRONIC PLUS.
The following subfunctions of DISTRONIC PLUS are described in a separate document:
- Automatic speed control
- Variable SPEEDTRONIC (except code 494 (USA version))
- Permanent limiter
The following graphic represents the mode of function of the DISTRONIC PLUS:
Detection range of DISTRONIC electric controller unit
Operation of the DISTRONIC PLUS takes place over the cruise control lever.
Design of the cruise control lever
If the SPEEDTRONIC LED 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.
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 driving immediately ahead can be set 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.
DISTRONIC electric controller unit evaluates the following input factors:
- The DISTRONIC PLUS is switched on over the CC lever (function requirements)
- Operating condition of engine/drivetrain (function requirements)
- Status of parking brake (function requirements)
- Engaged gear range (function requirements)
- Driver request via the cruise control lever
- Object recognition
- Engine drive torque
- Brake torque
- Vehicle speed/acceleration
- Acceleration/yaw rate
- Wheel angle
- Driver request to overtake (sets the turn signals on the combination switch)
- Brake pedal position
- Accelerator pedal position
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 from 01.03.2016 via chassis CAN 1 and up to 29.02.2016 via chassis CAN.
Operating condition for engine/drivetrain:
The CDI control unit or the ME-SFI [ME] control unit sends the "Engine running" or "Drivetrain operational" signal from 01.03.2016 via the chassis CAN 1 and up to 29.02.2016 via chassis CAN to the DISTRONIC electric controller unit.
Parking brake status:
The Electronic Stability Program control unit transmits the status of the parking brake (applied or released) from 01.03.2016 via chassis CAN 1 or up to 29.02.2016 via chassis CAN to the DISTRONIC controller unit.
Engaged gear range:
Information about the engaged gear range is sent by the fully integrated transmission control unit via the drive train CAN, CDI control unit or the ME-SFI [ME] control unit and chassis CAN 1 (from 01.03.2016) or the chassis CAN (up to 29.02.2016) to the DISTRONIC electric controller unit.
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 from 01.03.2016 via chassis CAN 1 and up to 29.02.2016 via the chassis CAN 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 from 01.03.2016 via chassis CAN 1 or up to 29.02.2016 via the chassis CAN 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:
Information about the engine torque currently available is sent by the CDI control unit or the ME-SFI [ME] control unit from 01.03.2016 via chassis CAN 1 and up to 29.02.2016 via the chassis CAN to the Electronic Stability Program control unit and the DISTRONIC electric controller unit.
Braking torque:
The Electronic Stability Program control unit transmits information about the currently applied braking torque from 01.03.2016 via chassis CAN 1 and up to 29.02.2016 via the chassis CAN to the DISTRONIC electric controller unit.
Acceleration/yaw rate:
The acceleration/yaw rate sensor for lateral and longitudinal acceleration records the acceleration/turn rate and sends this via the vehicle dynamics CAN, Electronic Stability Program control unit and chassis CAN 1 (from 01.03.2016) or chassis CAN (up to 29.02.2016) to the DISTRONIC electric controller unit.
On safety and comfort grounds the maximum (positive) acceleration of the automatic distance control is limited to about a = 2.5 m/s2
. It operates antiproportional to the vehicle speed, which means that the positive and negative accelerations reduce with increasing speed.
Wheel angle
In addition, the Electronic Stability Program control unit sends the wheel speed to the instrument cluster from 01.03.2016 via chassis CAN 1 and up to 29.02.2016 via the chassis CAN to the front SAM control unit and chassis CAN. The front SAM control unit calculates the wheel angle based on the position of both front wheels and sends corresponding information from 01.03.2016 via chassis CAN 1 and up to 29.02.2016 via the chassis CAN 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 CC lever and sends it to the DISTRONIC electric controller unit from 01.03.2016 via chassis CAN 1 and up to 29.02.2016 via chassis CAN to the DISTRONIC electric controller unit.
Brake pedal position:
The Electronic Stability Program control unit transmits the status of the brake pedal from 01.03.2016 via chassis CAN 1 and up to 29.02.2016 via chassis CAN to the DISTRONIC electric controller unit.
Accelerator pedal position:
The CDI control unit or the ME-SFI [ME] control unit sends information about the accelerator pedal position from 01.03.2016 via chassis CAN 1 and up to 29.02.2016 via chassis CAN to the DISTRONIC electric controller unit.
The DISTRONIC electric controller unit issues the following initial parameters (requests):
- Increase/reduce engine torque
- Engage targeted gear (back or upshift)
- Increase/reduce the braking torque
- Object information
- Emit warning tones, system or warning messages
Raise/reduce engine torque:
The Electronic Stability Program control unit transmits the request "Increase engine torque" or "Decrease engine torque" from 01.03.2016 via chassis CAN 1 and up to 29.02.2016 via the chassis CAN to the DISTRONIC electric controller unit. The Electronic Stability Program control unit evaluates the request as well as further vehicle dynamic requests and sends them according to their relevance from 01.03.2016 via chassis CAN 1 and up to 29.02.2016 via the chassis CAN to the CDI control unit or ME-SFI [ME] control unit. 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 "Engage targeted gear" request from 01.03.2016 via chassis CAN 1 or up to 29.02.2016 via the chassis CAN to the Electronic Stability Program control unit. The Electronic Stability Program control unit evaluates this request as well as further driving dynamics requests internally and transmits them, according to their relevance, via chassis CAN 1 (from 01.03.2016) or via the chassis CAN (up to 29.02.2016) to the CDI control unit (diesel engine) or the ME-SFI [ME] control unit (gasoline engine) and drive train CAN to the fully integrated transmission control unit. 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:
The DISTRONIC electric controller unit sends object information (e.g. the distance and differential speed to the target vehicle and the movement status of the target vehicle) from 01.03.2016 via chassis CAN 1 and up to 29.02.2016 via chassis CAN to the CDI control unit or the ME-SFI [ME] control unit.
Raise/reduce braking torque:
The DISTRONIC electric controller unit transmits the request "Increase braking torque" or "Decrease braking torque" from 01.03.2016 via chassis CAN 1 and up to 29.02.2016 via the chassis CAN 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.
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 from 01.03.2016 via chassis CAN 1, front SAM control unit and chassis CAN 2 and up to 29.02.2016 via chassis CAN 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:
- Activate DISTRONIC PLUS and drive off automatically
- Automatic distance control
- Change of driving lane (overtaking)
- Automatic speed control
- Going back into a lane/person in the front regulation
- Distance warning
- Adaptive brake assistant
- Autonomous partial braking
- Automated Stop Vehicle
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
- Automated drive-off from standstill with vehicle in detection range 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 drive-off procedure, the driver has to either briefly press the accelerator pedal or operate the Resume from memory switch on the CRUISE CONTROL lever to call up the last selected set speed (set speed > 30 km/h (mph)).
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.
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:
- Accelerator pedal position
- Driver request via the cruise control lever
- Object recognition
- Vehicle speed/acceleration
- Acceleration/yaw rate
- Brake pedal position
Initial parameters:
- Increase/reduce engine torque
- Engage targeted gear
- Object information
- Emit warning tones, system or warning messages
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:
- Increase/reduce engine torque
- Increase/reduce the braking torque
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.
- Object recognition
- Vehicle speed/acceleration
- Acceleration/yaw rate
- Engine drive torque
- Accelerator pedal position
- Driver request via the cruise control lever
- Brake pedal position
Initial parameters:
- Increase/reduce engine torque
- Increase/reduce the braking torque
- Engage targeted gear
- Object information
- Emit warning tones, system or warning messages
The automatic distance control is also active if the acceleration request from the driver is lower than the automatic distance control request.
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:
Change of driving lane (overtaking)
For overtaking above a speed of v = 60 km/h (mph) the vehicle is also accelerated automatically. 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.
The overtaking maneuver is broken off in the following situations:
- Risk of collision with the current target object
- Risk of collision with a vehicle moving directly at the side and ahead
Technical implementation
The DISTRONIC electric controller unit receives or sends the following information or requests for this:
Input factors:
- Object recognition
- Driver request over the combination switch
- Vehicle speed/acceleration
- Acceleration/yaw rate
- Engine drive torque
- Accelerator pedal position
Initial parameters:
- Increase/reduce engine torque
- Increase/reduce the braking torque
- Engage targeted gear
- Object information
- Emit warning tones, system or warning messages
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.
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:
- Object recognition
- Driver request via the cruise control lever
- Vehicle speed/acceleration
- Acceleration/yaw rate
- Engine drive torque
- Accelerator pedal position
- Brake pedal position
Initial parameters:
- Increase/reduce engine torque
- Engage targeted gear
- Increase/reduce the braking torque
- Object information
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 moving in vehicle is below the value which was programmed, the DISTRONIC PLUS function brakes the vehicle. If the requested brake power is not sufficient, a visual and an acoustic warning is issued, and the driver has to 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:
- Object recognition
- Vehicle speed
- Brake pedal position
Initial parameters:
- Increase/reduce engine torque
- Increase/reduce the braking torque
- Engage targeted gear
- Object information
- Emit warning tones, system or warning messages
Distance warning
DISTRONIC PLUS warns the driver visually and acoustically in a vehicle speed range of v = 7 to 250 km/h or the vehicle's maximum speed against driving obstacles on his/her lane. DISTRONIC PLUS differentiates here between a static (except CODE 494 (USA version)) and a collision-critical distance warning.
Static distance warning (except code 494 (USA version)):
Output of the static distance warning takes place purely optically. If the distance from the vehicle directly ahead goes below t = 0.8 s in flowing traffic and this critical distance is maintained 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 sends the request to output the warning from 01.03.2016 via chassis CAN 1, front SAM control unit and chassis CAN 2 and up to 29.02.2016 via chassis CAN 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 deemed to be critical (collision within t < 2.6 s), the DISTRONIC electric controller unit sends the request to issue the warning from 01.03.2016 via chassis CAN 1, front SAM control unit and chassis CAN 2 and up to 29.02.2016 via chassis CAN to the instrument cluster, which then actuates the DISTRONIC warning lamp and directly actuates the instrument cluster speaker (intermittent tone). Take-back of the warning only occurs if the situation has been defused.
Due warning of stationary obstacles is only given in a vehicle speed range v > 7 to 70 km/h.
Optical warning messages in instrument cluster
This is shown inversely on the multifunction display, i.e. the distance warning readiness indicator is hidden when the distance warning function is active. If the distance warning function is deactivated, the distance warning readiness indicator and the "OFF" lettering are shown.
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 1 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 of v = 7 to 250 km/h during an emergency braking with vehicles in front and in a vehicle speed range of v = 7 to 70 km/h for stationary obstacles.
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
- Vehicle speed: v = 7 to 200 km/h (moving towards vehicles driving immediately ahead and stationary obstacles)
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:
- Differential speed to vehicle or obstacle
- Distance from vehicle or obstacle
The DISTRONIC electric controller unit sends the appropriate request to increase the braking torque and to reduce the engine torque from 01.03.2016 via chassis CAN 1 and up to 29.02.2016 via chassis CAN to the Electronic Stability Program control unit. The Electronic Stability Program control unit evaluates the incoming requests actuates the traction system hydraulic unit directly and sends the request to reduce engine torque from 01.03.2016 via chassis CAN 1 and up to 29.02.2016 via chassis CAN to the CDI control unit or to the ME-SFI [ME] control unit.
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.
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 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).
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:
- Object recognition
- Vehicle speed
- Brake pedal position
Initial parameters:
- Increase/reduce engine torque
- Engage targeted gear
- Increase/reduce the braking torque
- Object information
The following traffic situations show the limits of DISTRONIC PLUS:
Obstacles and stationary vehicles
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 a stationary vehicle behind it, no automatic intervention by the brake system occurs.
Curves, curved entrances and exits
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
DISTRONIC PLUS may detect vehicles in cross traffic by mistake.
Offset driving style
For an activated distance control the vehicle can start off unintended, (e g. at a traffic light with cross-traffic).
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
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
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 | Model 172.4 as of model year 2016 up to model year 2017 with code 239 (Active Distance Assist DISTRONIC) | PE30.30-P-2053-97TAA | |
| Model 172.4 as of model year 2017 with code 239 (Active Distance Assist DISTRONIC) | PE30.30-P-2053-97TAB | ||
| Overview of system components for driver assistance systems | Model 172.4 as of model year 2016 up to model year 2017 with code 239 (Active Distance Assist DISTRONIC) | GF54.00-P-9998RD | |
| Model 172.4 as of model year 2017 with code 239 (Active Distance Assist DISTRONIC) | GF54.00-P-9998RDM |