Cruise Control (CC), Function - GF30.30-P-0001GWM
Model 463 (except 463.342)
as of model year 2019
Function requirements, general
- Engine running or drive train operational.
- Drive range "D" engaged (automatic transmission)
- Vehicle speed:
- Vehicle speed v > 30 to 250 km/h or maximum design speed (except code EM4 (Driving Assistance Plus Package)) or with deactivated distance control (with code EM4 (Driving Assistance Plus Package))
- Vehicle speed v > 30 to 200 km/h (with code EM4 (Driving Assistance Plus 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.
For vehicles with code EM4 (Driving Assistance Plus Package), the Distance Pilot DISTRONIC controller unit transmits function-relevant requests via suspension FlexRay to the Electronic Stability Program control unit. The Electronic Stability Program control unit processes these and prioritizes them according to the respective own evaluated parameters.
Tempomat button on multifunction steering wheel
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 altered in steps of v = 1 km/h or v = 10 km/h using the cruise control switch.
Actuation up to the actuation point increases the set speed by v = 1 km/h. If the switch is pressed beyond the actuation point then the specified speed increases each time by v = 10 km/h. If the switch is held at or beyond the actuation point, the specified speed is changed every t = 0.6 s.
The following input factors are evaluated to implement the function:
- Operating condition of engine/drivetrain (function requirements)
- Engaged gear range (function requirements)
- Vehicle speed
- Driver request via cruise control switch and cruise control resume switch
- Accelerator pedal position
Operating condition for engine/drivetrain:
The CDI control unit or ME-SFI control unit sends the "engine running" or "powertrain operational" signal via the drive CAN, powertrain control unit, and suspension FlexRay to the Electronic Stability Program control unit and for vehicles with code EM4 (Driving Assistance Plus Package) also to the Distance Pilot DISTRONIC controller 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:
Information on the engaged drive range is sent by the fully integrated transmission control unit via the drive CAN, powertrain control unit, and suspension FlexRay to the Electronic Stability Program control unit and for vehicles with code EM4 (Driving Assistance Plus Package) also to the Distance Pilot DISTRONIC controller unit.
Vehicle speed:
The vehicle speed is calculated by the Electronic Stability Program control unit from the wheel speeds.
For vehicles with code EM4 (Driving Assistance Plus Package), the Electronic Stability Program control unit sends the wheel speed signals also via the suspension FlexRay to the Distance Pilot DISTRONIC controller unit.
Driver request via cruise control switch and cruise control resume switch:
The Tempomat switch and the Tempomat resume switch send the driver requests via the steering wheel electronics, steering wheel CAN, steering column tube module control unit, and suspension FlexRay to the Electronic Stability Program control unit and for vehicles with code EM4 (Driving Assistance Plus Package) also to the Distance Pilot DISTRONIC controller unit.
Accelerator pedal position:
The powertrain control unit sends information on the accelerator pedal position via suspension FlexRay to the Electronic Stability Program control unit and for vehicles with code EM4 (Driving Assistance Plus Package) also to the Distance Pilot DISTRONIC controller unit.
The following initial parameters (requests) are issued to implement the function:
- Increase/reduce drive torque.
- Engage requested gear (downshift or upshift).
- Increase/reduce braking torque.
Increase/reduce the drive torque:
For vehicles except code EM4 (Driving Assistance Plus Package), the Electronic Stability Program control unit evaluates the input factors and further driving dynamic requests and sends the "increase/reduce drive torque" request via suspension FlexRay, powertrain control unit, and engine CAN to the CDI control unit or ME-SFI control unit.
For vehicles with code EM4 (Driving Assistance Plus Package), the Distance Pilot DISTRONIC controller unit sends the "increase/reduce drive torque" request via suspension FlexRay to the Electronic Stability Program 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 targeted gear (downshift or upshift):
For vehicles except code EM4 (Driving Assistance Plus Package), the Electronic Stability Program control unit evaluates the input factors and further dynamic driving requests and sends the "engage requested gear" request via suspension FlexRay, the powertrain control unit, and the drive CAN to the fully integrated transmission control unit.
For vehicles with code EM4 (Driving Assistance Plus Package), the Distance Pilot DISTRONIC controller unit sends the "engage requested gear" request via suspension FlexRay to the Electronic Stability Program 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 except code EM4 (Driving Assistance Plus Package), the Electronic Stability Program control unit evaluates the input factors and actuates the traction system hydraulic unit accordingly.
For vehicles with code EM4 (Driving Assistance Plus Package), the Distance Pilot DISTRONIC controller unit sends the "increase/reduce braking torque" request via suspension FlexRay to the Electronic Stability Program 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:
- Function sequence for automatic speed control
- Function sequence, variable speed limiter
Additional automatic speed control function requirements
- Tempomat selected via limiter switch (except code ZU8 (national version USA)) (limiter light-emitting diode off)
- Electronic Stability Program (ESP®) not switched to passive mode
Function sequence for automatic speed control
Through actuation of the cruise control resume switch, the last stored specified speed is applied, provided 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 except code EM4 (Driving Assistance Plus Package), the Electronic Stability Program control unit sends the set speed (specified speed) via suspension FlexRay, electronic ignition lock control unit, and user interface CAN to the instrument cluster.
For vehicles with code EM4 (Driving Assistance Plus Package), the Distance Pilot DISTRONIC controller unit sends the set speed (specified speed) via suspension FlexRay, electronic ignition lock control unit, and user interface CAN to the instrument cluster.
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:
- Push the cruise control resume switch downwards
- Switchover to the variable speed limiter
- Depressing the brake pedal
- Active regulation of the ESP® or ESP® switched off
- Speed v < 25 km/h
- Drive range does not correspond to "D" (automatic transmission). The following activities are started in order to reach or maintain the set speed:
- Increase/reduce drive torque.
- Engage requested gear (downshift or upshift).
- Increase/reduce braking torque.
Function sequence, variable speed limiter
The DTCO has the following subfunctions:
- Variable limiter function sequence (except code ZU8 (national version USA))
- Function sequence for permanent limiter
Additional variable limiter function requirements (except code ZU8 (national version USA))
- Variable speed limiter selected over variable speed limiter switch (variable speed limiter LED lights up):
The steering column tube module control unit actuates the variable speed limiter LED directly.
Variable limiter function sequence (except code ZU8 (national version USA))
The variable speed limiter can be used to limit the vehicle's maximum speed to a freely selectable value (e.g. v = 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 requested gear (shift down).
- Raise braking torque.
If the driver switches to the variable limiter on the steering wheel, the automatic speed control is deactivated. The following events deactivate the variable speed limiter:
- Push the cruise control resume switch downwards
- Changeover to CC
- Kickdown (accelerator pedal pressed > 90% and driven speed v < 20 km/h below the set maximum speed) (automatic transmission)
- ESP switched to passive mode
Function sequence for permanent limiter
The maximum speed of the vehicle can be limited in steps of v = 10 km/h from v = 160 to 240 km/h. Adjustment of the permissible maximum speed takes place in the menu "Settings", "Vehicle" and "Limitation (winter tires)" in the head unit. For navigation in the operating menu the following options are available:
- The navigation can occur using the Audio/COMAND control panel. The Audio/COMAND control panel sends the respective control signals via the telematics CAN to the head unit.
- Navigation can be operated via the touchpad. The touchpad sends the relevant operation signals to the head unit via the telematics CAN.
- The navigation can occur over voice control. The driver FSE microphone is directly read in by the head unit.
- The navigation can occur over 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 relevant control signals via the steering wheel electronics, the steering wheel CAN, 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 on the upper control panel control unit via the vehicle button. The vehicle button status is sent by the upper control panel control unit over the LCP-LIN, Audio/COMAND control panel and the telematics CAN to the head unit.
For vehicles except code EM4 (Driving Assistance Plus Package), the head unit sends the set maximum speed via the user interface CAN, electronic ignition lock control unit, and suspension FlexRay to the Electronic Stability Program control unit.
For vehicles with code EM4 (Driving Assistance Plus Package), the head unit sends the set maximum speed via the user interface CAN, electronic ignition lock control unit, and suspension FlexRay to the Distance Pilot DISTRONIC controller unit.
Approximately v = 10 km/h before reaching the set maximum speed a message appears in the instrument cluster multifunction display that indicates a maximum speed limitation. The driver can accelerate the vehicle up to the set maximum speed. The head unit transmits the set maximum speed via the user interface CAN, electronic ignition lock control unit and user interface CAN to the IC.
If the maximum speed was reached the following activities are started:
- Reduce drive torque.
- Engage requested gear (shift down).
- Raise braking torque.
The permanent limiter also remains active for a switched off variable speed limiter.
| Electrical function schematic for cruise control (CC) | PE30.30-P-2051-97ZGC | ||
| Overview of system components for driver assistance systems | GF54.00-P-9998GWM |