Cruise Control (CC), Function - GF30.30-P-0001FQ
MODEL 218
up to year 2015
As of 01.03.2013
Up to 28.02.2013
Function requirements, general
The units and values for the speed shown in the following text should be assigned to the possible national versions. The details in "miles per hour (mph)" refer to vehicles with a miles indicator.
- Engine running or drivetrain operational
- Gear range "D" engaged
- Vehicle speed v ≥ 30 km/h (v ≥ 20 mph) up to the design-dependent maximum speed
- Vehicle speed for active distance control v ≥ 30 to 200 km/h (for code (v ≥ 20 to 120 mph) (for code 233 (DISTRONIC PLUS))
Cruise control - general
The cruise control regulates the vehicle speed constantly to the target speed set by the driver.
To do this, the cruise control evaluates the driver's commands and the current driving condition.
The CC function is implemented dependent on the model and the equipment by the following control unit:
- Electronic Stability Program control unit (except model 218.374/974 and without code 233 (DISTRONIC PLUS))
- Premium Electronic Stability Program control unit (for code 233 (DISTRONIC PLUS) or model 218.374/974)
For vehicles with code 233 (DISTRONIC PLUS) the video and radar sensor system control unit transmits function-relevant requests via the chassis CAN (up to 28.02.2013) or chassis CAN 1 (as of 01.03.2013) 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 over the CC lever
The CC can be triggered using the following controls:
- Resume from memory switch
- Decelerate and set switch
- Accelerate and set switch
This sets the current vehicle speed as the target speed.
If a target speed was already set since the last engine start this can be called up by actuating the switch Resume from memory. The vehicle accelerates or decelerates to the last selected target speed.
Using the "decelerate and set" switch and the "accelerate and set" switch, the target speed can be altered in steps of v = 1 km/h (1 mph) or v = 10 km/h (5 mph).
Actuation up to the actuation point on the respective switch increases the target speed by v = 1 km/h (1 mph). If the switch is pressed beyond the actuation point then the target speed increases each time by v = 10 km/h (5 mph).
If the switch is held at or beyond the over-center preload the set speed is altered every t = 0.6 s.
The following input factors are evaluated to implement the function:
- Operating condition of engine/drivetrain (function requirements)
- Vehicle speed
- Engaged gear range (function requirements)
- Driver request via the cruise control lever
- Accelerator pedal position
Operating condition for engine/drivetrain:
The CDI control unit (for a diesel engine) or the ME-SFI [ME] control unit (for a gasoline engine) transmits the signal "Engine running" or "Drivetrain operational" via the chassis CAN (up to 28.02.2013) or chassis CAN 1 (from 01.03.2013) to the Electronic Stability Program control unit and for vehicles with code 233 (DISTRONIC PLUS) also to the video and radar sensor system control unit.
Vehicle speed:
The vehicle speed is calculated on the basis of the wheel speeds. The wheel speeds are detected by the RPM sensors. The Electronic Stability Program control unit directly reads in the signals from the RPM sensors. For vehicles with code 233 (DISTRONIC PLUS) the Electronic Stability Program control unit sends the signals from the RPM sensors via chassis CAN (up to 28.02.2013) or chassis CAN 1 (as of 01.03.2013) to the video and radar sensor system control 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 ME-SFI [ME] control unit and chassis CAN (up to 28.02.2013) or chassis CAN 1 (as of 01.03.2013) to the Electronic Stability Program control unit and, for vehicles with code 233 (DISTRONIC PLUS), also to the video and radar sensor system control 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 transmits the control signals of the CC lever via chassis CAN (up to 28.02.2013) or chassis CAN 1 (as of 01.03.2013) to the Electronic Stability Program control unit and for vehicles with code 233 (DISTRONIC PLUS) also to the video and radar sensor system control unit.
Accelerator pedal position:
Operation of the accelerator pedal is registered by the accelerator pedal sensor. The CDI control unit or ME-SFI [ME] control unit directly reads in the signals of the accelerator pedal sensor and transmits these via chassis CAN (up to 28.02.2013) or chassis CAN 1 (as of 01.03.2013) to the Electronic Stability Program control unit and for vehicles with code 233 (DISTRONIC PLUS) also to the video and radar sensor system control unit.
The following initial parameters (requests) are issued to implement the function:
- Increase/reduce engine torque
- Engage targeted gear (downshift or upshift), limit gear range
- Increase/reduce the braking torque
Raise/reduce engine torque:
The Electronic Stability Program control unit evaluates the input factors as well as further driving dynamic requests and transmits the request "increase/reduce engine torque" via chassis CAN (up to 28.02.2013) or chassis CAN 1 (as of 01.03.2013) 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.
Model 218
up to model year 2015
with code 233 (DISTRONIC PLUS)
The video and radar sensor system control unit sends the request "Raise/reduce engine torque" to the Electronic Stability Program control unit via chassis CAN (up to 28.02.2013) or chassis CAN 1 (as of 01.03.2013).
Engage targeted gear, limit gear range:
The ESP® control unit evaluates the input factors as well as further driving dynamic requests and transmits the request "Engage targeted gear" or "Limit gear range" via chassis CAN (up to 28.02.2013) or chassis CAN 1 (as of 01.03.2013), CDI control unit or the ME-SFI [ME] control unit and powertrain CAN to the fully integrated transmission control unit.
These requests should only be understood as a recommendation. Downshifting or upshifting of the A/T and limitation of the gear range takes place autonomously by the fully integrated transmission control unit, dependent on the current operating condition.
Model 218
up to model year 2015
with code 233 (DISTRONIC PLUS)
The video and radar sensor system control unit sends the request "Engage targeted gear" to the Electronic Stability Program control unit via chassis CAN (up to 28.02.2013) or chassis CAN 1 (as of 01.03.2013).
Raise/reduce braking torque:
The Electronic Stability Program control unit evaluates the input factors and actuates the traction system hydraulic unit appropriately. The traction system hydraulic unit reacts by increasing or reducing the braking torque.
Model 218
up to model year 2015
with code 233 (DISTRONIC PLUS)
The video and radar sensor system control unit sends the request "Raise/reduce braking torque" to the Electronic Stability Program control unit via chassis CAN (up to 28.02.2013) or chassis CAN 1 (as of 01.03.2013).
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 model 218.374/974)
- ESP® not switched into "SPORT HANDLING MODE" (for model 218.374/974)
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 set speed is displayed in the speedometer.
Vehicles without code 233 (DISTRONIC PLUS):
The Electronic Stability Program control unit transmits the appropriate information for vehicles up to 28.02.2013 via the chassis CAN to the IC. For vehicles from 01.03.2013 the Electronic Stability Program control unit sends this information via chassis CAN 1, the front SAM control unit and chassis CAN 2 to the IC.
Vehicles with code (233) Distronic Plus:
The video and radar sensor system control unit sends corresponding information for vehicles up to 28.02.2013 via chassis CAN to the instrument cluster. For vehicles from 01.03.2013 the video and radar sensor system control unit sends this information via chassis CAN 1, the front SAM control unit and chassis CAN 2 to the IC.
The following activities are started in order to reach or maintain the set speed:
- Increase/reduce engine torque
- Engage targeted gear (back or upshift)
- Increase/reduce the braking torque
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 target 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
- Depressing the brake pedal
- Operation of parking brake
- Active regulation of the ESP®
- Speed v < 25 km/h (v < 17 mph)
- Gear range not "D"
Function sequence for SPEEDTRONIC
The SPEEDTRONIC comprises the following subfunctions:
- Function sequence for variable SPEEDTRONIC (without 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)
- ESP® not passively engaged (except model 218.374/974)
- ESP® not switched into "SPORT HANDLING MODE" (for model 218.374/974)
- No "Kickdown" recognized
Function sequence for variable SPEEDTRONIC (without code 494 (USA version))
The maximum speed of the vehicle can be limited at any time to a freely selectable value (e.g. 50 km/h in urban traffic) over the variable SPEEDTRONIC. The driver can accelerate the vehicle up to the set limit. If the set limit was reached, the following activities are started:
- Reduce engine 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)
Function sequence for permanent limiter
The maximum speed of the vehicle can be limited in steps of v = 10 km/h (5 mph) of v = 160 to 240 km/h (100 to 150 mph).
Adjustment of the maximum speed takes place in the menu "Settings", "Vehicle" and "Limitation (winter tires)" in the instrument cluster.
Vehicles without code 233 (DISTRONIC PLUS):
The IC transmits the set maximum speed for vehicles up to 28.02.2013 via the chassis CAN to the Electronic Stability Program control unit. For vehicles from 01.03.2013 the IC sends this information via chassis CAN 2, the front SAM control unit and chassis CAN 1 to the Electronic Stability Program control unit.
Vehicles with code (233) (DISTRONIC PLUS):
The IC sends the set maximum speed for vehicles up to 28.02.2013 via chassis CAN to the video and radar sensor system control unit. For vehicles from 01.03.2013 the IC sends this information via chassis CAN 2, the front SAM control unit and chassis CAN 1 to the video and radar sensor system control unit.
At about v = 10 km/h (v = 5 mph) before reaching the set maximum speed, a message appears in the multifunction display which indicates limitation of the maximum speed.
The driver can accelerate the vehicle up to the set maximum speed. If the maximum speed was reached the following activities are started:
- Reduce engine torque
- Engage targeted gear (shift down)
- Reduce braking torque
| Electrical function schematic for cruise control (CC) | Model 218 up to model year 2015 except code 233 (DISTRONIC PLUS) | PE30.30-P-2051-97XAA | |
| Model 218 up to model year 2015 with code 233 (DISTRONIC PLUS) | PE30.30-P-2051-97XAB | ||
| Overview of system components for driver assistance systems | GF54.00-P-9998FQ |