Cruise Control (CC), Function - GF30.30-P-0001LF
Model 217, 222
up to model year 2018
Function requirements, general
- Engine running or drivetrain operational
- Gear range "D" engaged
- Vehicle speed:
- Vehicle speed v ≥ 30 km/h up to type-related maximum speed (except code 266 (DISTRONIC PLUS with Steer Assist and Stop & Go Pilot) or, on vehicles with code 266 (DISTRONIC PLUS with Steer Assist and Stop & Go Pilot) with deactivated distance control)
- Vehicle speed v ≥ 30 to 200 km/h (with code 266 (DISTRONIC PLUS with Steering Assist and Stop & Go Pilot) with 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 266 (DISTRONIC PLUS with Steer Assist and Stop & Go Pilot), the radar sensors control unit transmits function relevant requests via the chassis 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.
Operation of the CC function
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 target speed can be altered in steps of v = 1 km/h or v = 10 km/h using the "decelerate and set" switch and the "accelerate and set" switch.
On actuation up to the actuation point, the specified speed is changed by v = 1 km/h. On actuation past the actuation point, the specified speed is changed by v = 10 km/h in each case. 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:
- Engine running or drivetrain operational (function requirements)
- Engaged gear range (function requirements)
- Vehicle speed (function requirements)
- Driver request via the cruise control lever
- Accelerator pedal position
Engine running or drivetrain operational:
The CDI control unit or the ME-SFI [ME] control unit sends the "Engine running" or "Drivetrain operational" signal via the drive train CAN, powertrain control unit and chassis FlexRay to the Electronic Stability Program control unit and for vehicles with code 266 (DISTRONIC PLUS with Steer Assist and Stop & Go Pilot), also to the radar sensors control unit.
Model 222.004/057/104/157/163
up to model year 2018
All acceleration, deceleration or switching requests are coordinated by the CDI control unit or the ME-SFI [ME] control unit. The CDI control unit or the ME-SFI [ME] control unit prioritizes the requests, in line with their relevance, taking additional variables into account such as the charge level of the high voltage on-board electrical system, the operating condition of the ancillaries or requests from comfort systems such as the automatic air conditioning.
Engaged gear range:
Information about the gear range is sent by the fully integrated transmission control unit via the drive train CAN, powertrain control unit and the chassis FlexRay to the Electronic Stability Program control unit and, for vehicles with code 266 (DISTRONIC PLUS with Steer Assist and Stop & Go Pilot), also to the radar sensors control unit.
Vehicle speed:
The vehicle speed is calculated from the wheel speed signals. The Electronic Stability Program control unit directly reads in the signals from the rpm sensors.
For vehicles with code 266 (DISTRONIC PLUS with Steer Assist and Stop & Go Pilot), the Electronic Stability Program control unit transmits wheel speed signals via the chassis FlexRay to the radar sensors control unit.
Driver request via the cruise control lever:
The steering column tube module control unit reads in the driver requests directly via the cruise control lever, and transmits them via the suspension FlexRay to the Electronic Stability Program control unit; on vehicles with code 266 (DISTRONIC PLUS with Steer Assist and Stop & Go Pilot), it additionally transmits them to the radar sensors control unit.
Accelerator pedal position:
Information about the accelerator pedal position is sent by the CDI control unit or the ME-SFI [ME] control unit via the drive train CAN, powertrain control unit and the chassis FlexRay to the Electronic Stability Program control unit and also, for vehicles with code 266 (DISTRONIC PLUS with Steer Assist and Stop & Go Pilot), to the radar sensors control unit.
The following initial parameters (requests) are issued to implement the function:
- Increase/reduce engine torque
- Engage targeted gear (back or upshift)
- Increase/reduce the braking torque
Raise/reduce engine torque:
For vehicles without code 266 (DISTRONIC PLUS with Steer Assist and Stop & Go Pilot), the Electronic Stability Program control unit evaluates the input factors and other driving dynamic requests and transmits the "Increase/reduce engine torque" request via 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.
For vehicles with code 266 (DISTRONIC PLUS with Steer Assist and Stop & Go Pilot), the radar sensors control unit transmits the "Increase/reduce engine torque" request via the chassis 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.
Engage targeted gear:
For vehicles without code 266 (DISTRONIC PLUS with Steer Assist and Stop & Go Pilot), the Electronic Stability Program control unit evaluates the input factors along with additional driving dynamic requests and sends the "Engage targeted gear" request via the chassis FlexRay, powertrain control unit and the drive train CAN to the fully integrated transmission control unit.
For vehicles with code 266 (DISTRONIC PLUS with Steer Assist and Stop & Go Pilot), the radar sensors control unit transmits "Engage targeted gear" request via the chassis 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 however to be understood as a switching 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 266 (DISTRONIC PLUS with Steer Assist and Stop & Go Pilot), the Electronic Stability Program control unit evaluates the input factors and actuates the traction system hydraulic unit appropriately.
For vehicles with code 266 (DISTRONIC PLUS with Steer Assist and Stop & Go Pilot), the radar sensors control unit transmits the "Increase/reduce braking torque" request via the chassis FlexRay to the Electronic Stability Program control unit. The Electronic Stability Program control unit reacts by actuating the traction system hydraulic unit appropriately.
The traction system hydraulic unit reacts by increasing or reducing the braking torque.
Model 222.004/057/104/157/163
up to model year 2018
For model the kinetic energy is converted within defined limits into electrical energy (regenerative braking). If the required braking torque exceeds the deceleration through regenerative braking, the regenerative braking system control unit also actuates Electronic Stability Program control unit and the traction system hydraulic unit and therefore the service brake.
The cruise control function includes the following subfunctions:
- Function sequence for automatic speed control
- Function sequence for SPEEDTRONIC
Additional automatic speed control function requirements
- Cruise control selected using SPEEDTRONIC switch (without code 494 (USA version)) (SPEEDTRONIC LED off)
- Electronic Stability Program (ESP®) not passively switched (except engine 157, 279)
- ESP® not switched into "SPORT HANDLING MODE" (for engine 157, 279)
Function sequence for automatic speed control
Through actuation of the "Resume from memory" switch the last set speed stored is applied, provided a set speed was 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 266 (DISTRONIC PLUS with Steer Assist and Stop & Go Pilot), the Electronic Stability Program control unit sends appropriate information via the chassis FlexRay, electronic ignition lock control unit and user interface CAN to the instrument cluster.
For vehicles with code 266 (DISTRONIC PLUS with Steer Assist and Stop & Go Pilot), the radar sensors control unit sends this information via the chassis 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 activities are started in order to reach or maintain the set speed:
- Increase/reduce the drive torque
- Engage targeted gear (back or upshift)
- Increase/reduce the braking torque
The following events deactivate the automatic speed control:
- Operation of the OFF switch
- Changeover to the variable SPEEDTRONIC
- Depressing the brake pedal
- Active regulation of the ESP®
- Speed v < 25 km/h
- Gear range not "D"
Function sequence for SPEEDTRONIC
The SPEEDTRONIC encompasses the following subfunctions:
- Function sequence for variable SPEEDTRONIC (except code 494 (USA version))
- Function sequence for permanent limiter
Additional function requirements for variable SPEEDTRONIC (without code 494 (USA version))
- Variable SPEEDTRONIC selected with SPEEDTRONIC switch (SPEEDTRONIC LED lights up)
The steering column tube module control unit actuates the SPEEDTRONIC LED directly.
Function sequence for variable SPEEDTRONIC (except code 494 (USA version))
The variable SPEEDTRONIC 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 targeted gear (shift down)
- Raise braking torque
If switching takes place on the variable SPEEDTRONIC on the CC lever, the automatic speed control is deactivated.
The following events deactivate the variable SPEEDTRONIC:
- Operation of the OFF switch
- Kickdown (accelerator pedal pressed by > 90 % and driven speed v < 20 km/h removed from the set maximum speed)
- ESP® passively engaged (except model 157, 279)
- ESP® switched into "SPORT HANDLING MODE" (engine 157, 279)
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 maximum speed takes place in the menu "Settings", "Vehicle" and "Speed limitation (winter tires)" in the instrument cluster.
For vehicles without code 266 (DISTRONIC PLUS with Steer Assist and Stop & Go Pilot), the IC sends the set maximum speed via the user interface CAN, electronic ignition lock control unit and chassis FlexRay to the Electronic Stability Program control unit.
On vehicles with CODE 266 (DISTRONIC PLUS with Steer Assist and Stop & Go Pilot), the instrument cluster transmits the selected maximum speed via user interface CAN, electronic ignition lock control unit and chassis FlexRay to the radar sensors control unit.
Approx. v = 10 km/h before reaching the set speed, a message indicating the maximum speed limitation appears in the instrument cluster. The driver can accelerate the vehicle up to the set maximum speed.
If the set maximum speed is reached, the following activities are started:
- Reduce drive torque
- Engage targeted gear (shift down)
- Reduce braking torque
| Electrical function schematic for cruise control (CC) | Model 217, 222 up to model year 2018 except code 266 (DISTRONIC PLUS with Steer Assist and Stop & Go Pilot) | PE30.30-P-2051-97SEA | |
| Model 217, 222 up to model year 2018 with code 266 (DISTRONIC PLUS with Steer Assist and Stop & Go Pilot) | PE30.30-P-2051-97SEB | ||
| Overview of system components for driver assistance systems | GF54.00-P-9998LF |