Cruise Control (CC), Function - GF30.30-S-0014TRF
Model 447
With Code MS1 (Cruise control)
With Code XM0 (Facelift)
Shown On Model 447.8 with engine 654
Shown On Model 447.6/7 with engine 654
Function requirements, general
- Engine running or drive train operational.
- Gear range "D" engaged (with code G42 (7G-TRONIC PLUS) or with code G43 (9G-TRONIC))
- Vehicle speed:
- V ≥ 30 to 250 km/h or maximum design speed (without code ET4 (Active Distance Assist DISTRONIC)) or with deactivated distance control (with code ET4 (Active Distance Assist DISTRONIC))
- V ≥ 30 to 200 km/h (with code ET4 (Active Distance Assist DISTRONIC)) and distance control activated
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 ET4 (Active Distance Assist DISTRONIC), the Active Distance Assist electric controller unit sends function-relevant requests via the chassis CAN to the Electronic Stability Program control unit (ESP). The Electronic Stability Program (ESP) control unit processes these and prioritizes them according to the respective own evaluated parameters.
Operation of cruise control using the cruise control lever, Shown On Model 447.8
The cruise control is activated using the "Resume from memory" switch (12). Here the last stored or momentary vehicle speed is set as the set speed.
The specified speed can be changed in 1 or 10 km/h increments via the decelerate and set (14) switch and the accelerate and set switch (10).
Actuation up to the pressure point alters the specified speed by v = 1 km/h. If the respective switch is pressed beyond the pressure point, the specified speed then alters by v = 10 km/h each time. If the respective switch is held at or beyond the pressure point, the specified speed is then 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 the cruise control lever
- Accelerator pedal position
Operating condition of engine/drivetrain (function requirements)
The CDI control unit or the ME control unit sends the "Engine running" or "Drivetrain operational" signal to the Electronic Stability Program control unit (ESP) and for vehicles with code ET4 (Active Distance Assist DISTRONIC) to the Active Distance Assist electric controller unit additionally.
All acceleration, deceleration or switching requests are coordinated by the CDI control unit or the ME control unit. The CDI control unit or the ME control unit prioritizes the requests according to their relevance; taking additional variables such as the operating status of ancillary equipment or the requirements of comfort systems such as the automatic climate control into account.
Engaged gear range (function requirements)
Vehicles with code G42 (7G-TRONIC PLUS) or with code G43 (9G-TRONIC)
Information on the gear engaged is sent by the fully integrated transmission control (VGS) electric controller unit to the Electronic Stability Program (ESP) control unit and for vehicles with code ET4 (Active Distance Assist DISTRONIC) to the Active Distance Assist electric controller unit additionally.
Vehicle speed
The vehicle speed is calculated by the Electronic Stability Program (ESP) control unit based on the wheel speed.
For vehicles with code ET4 (Active Distance Assist DISTRONIC), the Electronic Stability Program (ESP) control unit also sends the vehicle speed to the Active Distance Assist electric controller unit.
Driver request via the cruise control lever
The driver requests made via the cruise control lever (S40/4) are read in directly by the steering column tube module (MRM) control unit. The steering column tube module (MRM) control unit sends the control signals of the cruise control lever to the Electronic Stability Program (ESP) control unit and for vehicles with code ET4 (Active Distance Assist DISTRONIC) to the Active Distance Assist electric controller unit additionally.
The CDI control unit or the ME control unit sends information on the accelerator pedal position to the Electronic Stability Program (ESP) control unit and for vehicles with code ET4 (Active Distance Assist DISTRONIC) to the Active Distance Assist electric controller unit additionally.
Accelerator pedal position
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 without code ET4 (Active Distance Assist DISTRONIC), the Electronic Stability Program (ESP) control unit evaluates the input factors as well as additional driving dynamic requirements and sends the "Increase/reduce drive torque" request to the CDI control unit or ME control unit.
For vehicles with code ET4 (Active Distance Assist DISTRONIC), the Active Distance Assist electric controller sends the "Increase/reduce drive torque" request to the Electronic Stability Program (ESP) control unit. The Electronic Stability Program (ESP) control unit evaluates this and sends it according to its priority to the CDI control unit or ME control unit.
The CDI control unit or ME control unit implement the request accordingly.
Engage targeted gear (back or upshift)
Vehicles with code G42 (7G-TRONIC PLUS) or with code G43 (9G-TRONIC)
For vehicles without code ET4 (Active Distance Assist DISTRONIC), the Electronic Stability Program (ESP) control unit evaluates the input factors as well as additional driving dynamic requirements and sends the "Engage requested gear" request to the fully integrated transmission control (VGS) electric controller unit.
For vehicles with code ET4 (Active Distance Assist DISTRONIC), the Active Distance Assist electric controller unit sends the "Engage requested gear" request to the Electronic Stability Program (ESP) control unit. The Electronic Stability Program (ESP) control unit evaluates these and sends them according to their priority to the fully integrated transmission control (VGS) electric controller unit.
This request is to be understood as a shift recommendation.
Downshifting or upshifting of the A/T takes place autonomously by the fully integrated transmission electric controller unit (VGS), dependent on the current operating condition.
Increase/reduce the braking torque
For vehicles without code ET4 (Active Distance Assist DISTRONIC), the Electronic Stability Program (ESP) control unit evaluates the input factors and actuates the traction system hydraulic unit (1) accordingly.
For vehicles with code ET4 (Active Distance Assist DISTRONIC), the Active Distance Assist electric controller sends the "Increase/reduce braking torque" request to the Electronic Stability Program (ESP) control unit.
The Electronic Stability Program (ESP) 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 for SPEEDTRONIC
Additional automatic speed control function requirements
- Cruise control is selected via the SPEEDTRONIC switch (15): The SPEEDTRONIC (11) LED does not light up.
- Electronic Stability Program (ESP®) not switched to passive mode
Function sequence for automatic speed control
By actuating the "Resume from memory" switch (12), the last specified speed stored is applied, provided a specified speed has been stored since the engine was last started. If no set speed was stored, the current vehicle speed is set as the set speed. The set speed is shown in the IC (IC) control unit's multifunction display.
Model 447.8 :
- For vehicles without code ET4 (Active Distance Assist DISTRONIC), the Electronic Stability Program (ESP) control unit sends the set speed (specified speed) to the instrument cluster (KI) control unit.
- For vehicles with code ET4 (Active Distance Assist DISTRONIC), the Active Distance Assist electric controller unit sends the set speed (specified speed) to the instrument cluster (KI) control unit.
Model 447.6/7 :
- The Electronic Stability Program control unit (ESP) sends the vehicle speed via chassis CAN to the IC control unit (IC).
The driver also has the option to accelerate beyond the set specified speed by actuating 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:
- Actuation of the "OFF" switch (16)
- Switch over to the variable SPEEDTRONIC
- Depressing the brake pedal
- Active regulation of the ESP®
- Speed v < 25 km/h
- Drive range does not correspond to "D" (with code G42 (7G-TRONIC PLUS) or with code G43 (9G-TRONIC))
The following activities are started in order to reach or maintain the set speed:
- Increase/reduce drive torque.
- Engage requested gear (shift down or up) (with code G42 (7G-TRONIC PLUS) or with code G43 (9G-TRONIC))
- Increase/reduce braking torque.
Function sequence for SPEEDTRONIC
The SPEEDTRONIC comprises the following subfunctions:
- Function sequence for variable SPEEDTRONIC
- Function sequence for permanent limiter
Additional function requirements for variable SPEEDTRONIC
- Variable SPEEDTRONIC is selected via the SPEEDTRONIC (15) switch: The SPEEDTRONIC (11) lights up.
The steering column tube module control unit (MRM) actuates the LED SPEEDTRONIC directly.
Function sequence for variable SPEEDTRONIC
The variable SPEEDTRONIC can be used to limit the maximum speed of the vehicle 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) (with code G42 (7G-TRONIC PLUS) or with code G43 (9G-TRONIC))
- 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:
- Actuation of the "OFF" switch (16)
- Kickdown (accelerator pedal actuation > 90 % and driven speed v < 20 km/h than the maximum set speed) (with code G42 (7G-TRONIC PLUS) or with code G43 (9G-TRONIC))
- 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. The maximum speed is adjusted in the settings menu → Vehicle → Limitation (winter tires) in instrument cluster control unit (KI).
Model 447.8 :
- For vehicles without code ET4 (Active Distance Assist DISTRONIC), the instrument cluster (KI) control unit sends the set maximum speed to the Electronic Stability Program control unit (ESP).
- For vehicles with code ET4 (Active Distance Assist DISTRONIC), the instrument cluster (KI) control unit sends the set maximum speed to the Active Distance Assist electric controller unit.
Model 447.6/7 :
- The IC control unit (IC) sends the set maximum speed via chassis CAN to the Electronic Stability Program control unit (ESP).
Approx. v = 10 km/h before reaching the selected maximum speed, a message appears in the front passenger display of the instrument cluster (KI) control unit indicating the maximum speed limitation. The driver can accelerate the vehicle up to the set maximum speed.
When the max. set speed has been reached, the following activities are started:
- Reduce drive torque.
- Engage requested gear (shift down) (with code G42 (7G-TRONIC PLUS) or with code G43 (9G-TRONIC))
- Reduce braking torque.
| Overview of system components for driver assistance systems | GF54.00-S-9998TRF |