Cruise Control (CC), Function - GF30.30-P-0001FH
Model 238
Up To Model Year 2021
Function requirements, general
- Engine running or drivetrain operational
- Gear range "D" engaged (transmission 725)
- Vehicle speed:
- Vehicle speed 30 to 250 km/h or maximum design speed (except code 239 (Distance Pilot DISTRONIC) and except code 23P (Driving Assistance Package)) or with deactivated distance control (with code 239 (Distance Pilot DISTRONIC) or code 23P (Driving Assistance Package))
- Vehicle speed 30 to 200 km/h (with code 239 (Distance Pilot DISTRONIC) or code 23P (Driving Assistance Package) and activated distance control)
- Vehicle speed 30 to 210 km/h (with code 23P (Driving Assistance Package) and activated distance control)
Cruise control - general
The cruise control regulates the vehicle speed constantly and automatically to the desired speed set by the driver. To do this, the cruise control evaluates the driver's commands and the current driving condition.
The functionally relevant requests are transmitted via the suspension FlexRay to the Electronic Stability Program control unit for vehicles with code 239 (Distance Pilot DISTRONIC) by the Distance Pilot DISTRONIC control unit or for vehicles with code 23P (Driving Assistance Package) by the Mercedes-Benz Intelligent Drive control unit. The Electronic Stability Program control unit processes these and prioritizes them according to the respective own evaluated parameters.
Cruise control operation, shown on model 238.3 Up To Model Year 2019
Multifunction steering wheel, shown on model 238.3 as of model year 2019, left-hand drive vehicle except code L5C (Multifunction sports steering wheel in nappa leather)
Multifunction steering wheel, shown on model 238.3 as of model year 2019, left-hand drive vehicle With Code L5C (Multifunction sports steering wheel in nappa leather)
Model 238 Up To Model Year 2019
The cruise control is activated using the resume from memory switch. Here the last stored or momentary vehicle speed is set as the set speed.
The specified speed can be changed in steps of 1 km/h or 10 km/h using the decelerate and set switch and the accelerate and set switch. Actuation up to the pressure point changes the specified speed by 1 km/h. If the switch is actuated beyond the pressure point, the specified speed changes by 10 km/h each time. If the switch is held at or beyond the pressure point, the specified speed is changed every 0.6 s.
Model 238 as of model year 2019
The cruise control is activated with the stored specified speed using the cruise control resume switch (top switch position). If the cruise control is already activated, the current speed limit will be adopted as the new specified speed. The cruise control is switched off by pushing the cruise control resume switch downwards.
The specified speed can be changed in steps of 1 km/h or 10 km/h using the cruise control switch.
Actuation up to the pressure point changes the specified speed by 1 km/h. If the switch is actuated beyond the pressure point, the specified speed changes by 10 km/h each time. If the switch is held at or beyond the pressure point, the specified speed is changed every 0.6 s.
The following input factors are evaluated to implement the function:
- Operating condition of engine/drivetrain (function requirements)
- Engaged gear range (transmission 725) (function requirements)
- Vehicle speed
- Driver request using cruise control lever (up to model year 2019)
- Driver request using cruise control switch and cruise control resume switch (as of model year 2019)
- Accelerator pedal position
Operating condition for engine/drivetrain:
The CDI control unit or the ME-SFI [ME] control unit transmits the "Engine running" signal or "Drivetrain operational" signal via the drive CAN, powertrain control unit and suspension FlexRay to the Electronic Stability Program control unit and for vehicles with code 239 (Distance Pilot DISTRONIC) also to the Distance Pilot DISTRONIC control unit or for vehicles with code 23P (Driving Assistance Package) to the Mercedes-Benz Intelligent Drive control unit.
The CDI control unit or the ME-SFI [ME] control unit, amongst other things, coordinates acceleration, deceleration or switching requirements. In doing so it prioritizes requests according to their relevance, while taking account of the additional variables such as the charge level of the high voltage on-board electrical system, the operating condition of the ancillaries or requests from the comfort systems such as the AAC.
Engaged gear range:
The fully integrated transmission control unit transmits information on the engaged drive range via the drive CAN, powertrain control unit and suspension FlexRay to the Electronic Stability Program control unit and for vehicles with code 239 (Distance Pilot DISTRONIC) also to the Distance Pilot DISTRONIC control unit or for vehicles with code 23P (Driving Assistance Package) to the Mercedes-Benz Intelligent Drive control unit.
Vehicle speed:
The vehicle speed is calculated by the Electronic Stability Program control unit from the wheel speeds.
For vehicles with code 239 (DISTRONIC PLUS), the Electronic Stability Program control unit also transmits the wheel speed signals via chassis FlexRay to the DISTRONIC Distance-Pilot controller unit. For vehicles with code 23P (Driving Assistance Package), the Electronic Stability Program control unit additionally transmits the wheel speed signals to the Mercedes-Benz Intelligent Drive control unit via the suspension FlexRay.
Driver request using cruise control lever (Up To Model Year 2019) :
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 transmits the cruise control lever operation signals via the suspension FlexRay to the Electronic Stability Program control unit and additionally to the Distance Pilot DISTRONIC controller unit in vehicles with code 239 (Distance Pilot DISTRONIC) or to the Mercedes-Benz Intelligent Drive control unit in vehicles with code 23P (Driving Assistance Package).
Driver request using cruise control switch and cruise control resume switch (as of model year 2019) :
The cruise control switch and the cruise control resume switch are read in by the steering wheel electronics. The steering wheel electronics transmit the driver requests via the steering wheel CAN, the steering column tube module control unit, and the suspension FlexRay to the Electronic Stability Program control unit and additionally to the Distance Pilot DISTRONIC controller unit in vehicles with code 239 (Distance Pilot DISTRONIC) or to the Mercedes-Benz Intelligent Drive control unit in vehicles with code 23P (Driving Assistance Package).
Accelerator pedal position:
The powertrain control unit transmits information on the accelerator pedal position via the suspension FlexRay to the Electronic Stability Program control unit and for vehicles with code 239 (Distance Pilot DISTRONIC) also to the Distance Pilot DISTRONIC control unit or for vehicles with code 23P (Driving Assistance Package) to the Mercedes-Benz Intelligent Drive control unit.
The following initial parameters (requests) are issued to implement the function:
- Increase/reduce the drive torque
- Engage targeted gear (downshift or upshift) (transmission 725)
- Increase/reduce the braking torque
Increase/reduce the drive torque:
For vehicles without code 239 (DISTRONIC PLUS) and without code 23P (Driving Assist Package Plus), the Electronic Stability Program control unit evaluates the input factors and other driving dynamic requests and transmits the "Increase/reduce drive torque" request via chassis FlexRay, powertrain control unit and engine CAN to the CDI control unit or the ME-SFI [ME] control unit.
The "Increase/reduce drive torque" request is transmitted via the suspension FlexRay to the Electronic Stability Program control unit for vehicles with code 239 (Distance Pilot DISTRONIC) by the Distance Pilot DISTRONIC control unit or for vehicles with code 23P (Driving Assistance Package) by the Mercedes-Benz Intelligent Drive control unit. The Electronic Stability Program control unit processes this and transmits it according to its priority via the chassis FlexRay, powertrain control unit and engine 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.
Engage target gear (downshift or upshift) (transmission 725) :
For vehicles without code 239 (DISTRONIC Distance-Pilot) and without code 23P (Driving Assist Package Plus), the Electronic Stability Program control unit evaluates the input factors and other driving dynamic requests and transmits the "Engage targeted gear" request via chassis FlexRay, powertrain control unit and drive train CAN to the fully integrated transmission control unit.
The "Engage requested gear" request is transmitted via the suspension FlexRay to the Electronic Stability Program control unit for vehicles with code 239 (Distance Pilot DISTRONIC) by the Distance Pilot DISTRONIC control unit or for vehicles with code 23P (Driving Assistance Package) by the Mercedes-Benz Intelligent Drive control unit. The Electronic Stability Program control unit processes this and transmits it according to its priority via the chassis FlexRay, powertrain control unit 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 automatic transmission takes place autonomously by the fully integrated transmission control unit dependent on the current operating condition.
Raise/reduce braking torque:
For vehicles without code 239 (DISTRONIC Distance-Pilot) and without code 23P (Driving Assist Package Plus), the Electronic Stability Program control unit evaluates the input factors and actuates the traction system hydraulic unit accordingly.
The "Increase/reduce braking torque" request is transmitted via the suspension FlexRay to the Electronic Stability Program control unit for vehicles with code 239 (Distance Pilot DISTRONIC) by the Distance Pilot DISTRONIC control unit or for vehicles with code 23P (Driving Assistance Package) by the Mercedes-Benz Intelligent Drive control unit. The Electronic Stability Program control unit evaluates these and actuates the traction system hydraulic unit appropriately.
The traction system hydraulic unit reacts by increasing or reducing the braking torque.
Cruise control encompasses the following subfunctions:
- Automatic speed control
- Limiter
Additional automatic speed control function requirements
- Cruise control selected using limiter switch (except code 494 (USA version)) (limiter light-emitting diode does not light up) (up to model year 2019)
- Cruise control selected using cruise control switch (except code 494 (USA version)) (as of model year 2019)
- Electronic Stability Program (ESP®) not switched to passive mode
Automatic speed control
The last specified speed stored is set by actuating the resume from memory switch (up to model year 2019) or the cruise control resume switch (as of model year 2019) provided that a specified speed has been stored since the last engine start. If no set speed was stored, the current vehicle speed is set as the set speed. The target speed is displayed in the IC.
For vehicles without code 239 (DISTRONIC Distance-Pilot) and without code 23P (Driving Assist Package Plus), the Electronic Stability Program control unit transmits the set speed (target speed) via chassis FlexRay, electronic ignition lock control unit and user interface CAN to the instrument cluster.
The set speed (specified speed) is transmitted via the suspension FlexRay, electronic ignition lock control unit and user interface CAN to the instrument cluster for vehicles with code 239 (Distance Pilot DISTRONIC) by the Distance Pilot DISTRONIC control unit or for vehicles with code 23P (Driving Assistance Package) by the Mercedes-Benz Intelligent Drive control unit.
The driver also has the option to accelerate beyond the set target speed through actuation of the accelerator pedal (for example when overtaking). The set speed is regulated again after removal of the acceleration request (releasing the accelerator pedal).
The following events deactivate the automatic speed control:
- Operation of the OFF switch
- Switchover to the variable speed limiter
- Depressing the brake pedal
- Active regulation of the ESP® or ESP® switched off
- Speed over 25 km/h
- Gear range is not "D" (transmission 725)
The following activities are started in order to reach or maintain the set speed:
- Increase/reduce the drive torque
- Engage targeted gear (downshift or upshift) (transmission 725)
- Increase/reduce the braking torque
Limiter
The DTCO has the following subfunctions:
- Variable speed limiter (except code 494 (USA version))
- Permanent limiter
Additional function sequence for variable speed limiter (except code 494 (USA version))
- Variable limiter selected using limiter switch (limiter light-emitting diode lights up) (up to model year 2019) :
The steering column tube module control unit actuates the variable speed limiter LED directly.
- Variable limiter selected using limiter and Distance Pilot switch (as of model year 2019 with code L5C (Multifunction sports steering wheel in nappa leather))
- Variable limiter selected using limiter and Distance Pilot switch (as of model year 2019 except code L5C (Multifunction sports steering wheel in nappa leather))
Variable speed limiter (except code 494 (USA version))
The variable limiter can be used to limit the vehicle's speed to a freely selectable value (e.g. 50 km/h in urban traffic). The driver can accelerate the vehicle up to the set limit.
If the set limit was reached, the following activities are started:
- Reduce drive torque
- Engage targeted gear (downshift) (transmission 725)
- Raise braking torque
Model 238
up to model year 2019
If switching takes place on the variable SPEEDTRONIC on the CC lever, the automatic speed control is deactivated.
Model 238
as of model year 2019 up to model year 2021
If a switch is made to the variable limiter on the limiter and Distance Pilot switch (with code L5C (Multifunction sports steering wheel in nappa leather)) or the limiter and Distance Pilot button (except code L5C (Multifunction sports steering wheel in nappa leather)), automatic speed control is deactivated.
The following events deactivate the variable speed limiter:
- Operation of the OFF switch
- Changeover to CC
- Kickdown (accelerator pedal actuation over 90 % and vehicle speed less than 20 km/h from the set speed) (transmission 725)
- ESP switched to passive mode
Permanent limiter
The vehicle's speed can be limited in 10 km/h steps from 160 to 240 km/h. The speed is adjusted in the "Settings", "Vehicle" and "Limitation (winter tires) " menu in the head unit. For navigation in the operating menu the following options are available:
- Except code 446 (Touchpad only), the navigation takes place with the Audio/COMAND control panel. The Audio/COMAND control panel sends the corresponding control signals (except code 446 (Touchpad only)) to the head unit via the telematics CAN.
- With code 446 (Touchpad only) or code 448 (Touchpad), the navigation takes place with the Touchpad. The touchpad (with code 446 (Touchpad only)) or code 448 (Touchpad)) transmits the respective control signals via the telematics CAN to the head unit.
- With code 531 (COMAND APS), navigation can be carried out using voice control. The driver hands-free system microphone transmits the signals directly to the head unit.
- Navigation can be performed via the head unit finger navigation pad and the "Back" button on the steering wheel. The head unit finger navigation pad and the "Back" button transmit the corresponding operation signals via the steering wheel electronics, the steering LIN (up to model year 2019) or the steering wheel CAN (as of model year 2019), the steering column tube module control unit, the suspension FlexRay, the electronic ignition lock control unit, and the user interface CAN to the head unit.
- The operating menu can be called up over vehicle button the upper control panel control unit (with code 246 (Analog clock)). The status of the Vehicle button is transmitted by the upper control panel control unit via the LCP-LIN, the Audio/COMAND control panel (except code 446 (Touchpad only)) or the touchpad (with code 446 (Touchpad only)) and the telematics CAN to the head unit.
In vehicles except code 239 (Distance Pilot DISTRONIC) and except code 23P (Driving Assistance Package), the head unit transmits the set speed via the user interface CAN, the electronic ignition lock control unit, and the suspension FlexRay to the Electronic Stability Program control unit.
In vehicles with code 239 (Distance Pilot DISTRONIC), the head unit transmits the set speed via the user interface CAN, the electronic ignition lock control unit, and the suspension FlexRay to the Distance Pilot DISTRONIC controller unit.
In vehicles with code 23P (Driving Assistance Package), the head unit transmits the set speed via the user interface CAN, the electronic ignition lock control unit, and the suspension FlexRay to the Mercedes-Benz Intelligent Drive control unit.
Approx. 10 km/h before the set speed is reached, a message indicating the speed limit appears on the instrument cluster's multifunction display. The driver can accelerate the vehicle up to the set maximum speed. The head unit transmits the set speed via the user interface CAN, the electronic ignition lock control unit, and the user interface CAN to the instrument cluster.
When the set speed has been reached, the following activities are started:
- Reduce drive torque
- Engage targeted gear (downshift) (transmission 725)
- Raise braking torque
The permanent limiter also remains active for a switched off variable speed limiter.
| Electrical function schematic for cruise control (CC) | Model 238 up to model year 2021 except code 239 (Adaptive cruise control Pro (DISTRONIC PRO)) except code 23P (Drive package) | PE30.30-P-2051-97DCA | |
| Model 238 up to model year 2019 with code 239 (Adaptive cruise control Pro (DISTRONIC PRO)) Model 238 up to model year 2019 with code 23P (Drive package) | PE30.30-P-2051-97DCB | ||
| Model 238 as of model year 2019 up to model year 2021 with code 239 (Adaptive cruise control Pro (DISTRONIC PRO)) Model 238 as of model year 2019 up to model year 2021 with code 23P (Drive package) | PE30.30-P-2051-97DCC | ||
| Overview of system components for driver assistance systems | GF54.00-P-9998FH |