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Cruise Control (CC), Function - GF30.30-P-0001CE

MODEL 204 with CODE (440) Cruise control as of model year 2009/YoM 08 

MODEL 204.0/2 with CODE (233) Distronic Plus with CODE (237) Active Blind Spot Assist with CODE (238) Active Lane Keeping Assist as of model year 2012/YoM 11 facelift 

MODEL 204.3 with CODE (233) Distronic Plus with CODE (237) Active Blind Spot Assist with CODE (238) Active Lane Keeping Assist 

MODEL 204.9 with CODE (233) Distronic Plus with CODE (237) Active Blind Spot Assist with CODE (238) Active Lane Keeping Assist as of model year 2013/Facelift 12 

Fig 1: Cruise Control - Block Diagram
G10084407Courtesy of MERCEDES-BENZ USA

Cruise control function requirements 

IMPORTANT The units and values given in the following text for the speed must be assigned to the possible national versions. The details in "miles per hour (mph)" refer to vehicles with a miles indicator.

Cruise control - general 

The CC function constantly regulates the vehicle speed and automatically to the specified sped set by the driver.

To do this the CC function evaluates the operator requests made by the driver and the current driving status.

The CC function is implemented according to the installed equipment by the following control unit:

For vehicles with code (233) DISTRONIC PLUS, code (237) Active Blind Spot Assist or code (238) Active Lane Keeping Assist the video and radar sensor system control unit transmits function-relevant requests via chassis CAN to the Electronic Stability Program control unit. The Electronic Stability Program control unit receives and processes these and prioritizes them according to the respective own evaluated parameters.

Operation of the CC function over the CC lever 

Fig 2: Identifying Cruise Control Lever Adjustment Position
G10084408Courtesy of MERCEDES-BENZ USA

The CC function is activated over the "Resume from memory" switch. In the process the last stored or current vehicle speed is set as the specified speed.

The specified speed can be altered in Operation steps of v = 1 km/h (1 mph) or v = 10 km/h (5 mph) over the Decelerate and Fix in place switch and the Accelerate and Fix in place switch.

Actuation up to the actuation point increases the specified speed by v = 1 km/h (1 mph).

If the switch is actuated beyond the actuation point then the specified speed increases each time by v = 10 km/h (5 mph). If the switch is held at or over the actuation point then the specified speed alters once every t = 0.6 s.

The following input factors are evaluated to implement the CC function: 

Operating condition of engine/drivetrain:

The CDI control unit or the ME-SFI [ME] control unit transmits the signal "Engine runs" or "Drivetrain operational" via the chassis CAN to the Electronic Stability Program control unit and for vehicles with code (233) DISTRONIC PLUS, code (237) Active Blind Spot Assist or code (238) Active Lane Keeping Assist to the video and radar sensor system control unit.

Vehicle speed:

The vehicle speed is calculated on the basis of the wheel speeds. The rotational speed sensors detect the wheel speeds.

The Electronic Stability Program control unit directly reads in the signals from the rpm sensors and transmits these for vehicles with code (233) DISTRONIC PLUS, code (237) Active Blind Spot Assist or code (238) Active Lane Keeping Assist via the chassis CAN to the video and radar sensor system control unit.

Engaged gear range (for transmission 722):

The electronic transmission control control unit (transmission 722.6) or the fully integrated transmission control unit (transmission 722.9) transmits information to the gear range via the chassis CAN to the Electronic Stability Program control unit and for vehicles with code (233) DISTRONIC PLUS, code (237) Active Blind Spot Assist or code (238) Active Lane Keeping Assist to the video and radar sensor system control unit.

Driver request via the cruise control lever

The driver requests made over the CC lever are read in directly by the steering column tube module control unit. The steering column tube module control unit transmits the control signals of the CC lever via the chassis CAN to the Electronic Stability Program control unit and for vehicles with code (233) DISTRONIC PLUS, code (237) Active Blind Spot Assist or code (238) Active Lane Keeping Assist 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 the ME-SFI [ME] control unit directly reads in the signals from the accelerator pedal sensor and transmits these via the chassis CAN to the Electronic Stability Program control unit and also for vehicles with code (233) DISTRONIC PLUS, code (237) Active Blind Spot Assist or code (238) Active Lane Keeping Assist to the video and radar sensor system control unit.

The following initial parameters (requests) are issued to implement the CC function: 

Increase/reduce engine torque

The Electronic Stability Program control unit evaluates the input factors as well as further vehicle dynamic requests and transmits the request "Increase/reduce engine torque" via the chassis 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.

IMPORTANT For vehicles with code (233) DISTRONIC PLUS, code (237) Active Blind Spot Assist or code (238) Active Lane Keeping Assist, the video and radar sensor system control unit transmits the request "Increase/reduce engine torque" via the chassis CAN to the Electronic Stability Program control unit.

Engage the targeted gear (for transmission 722):

The Electronic Stability Program control unit evaluates the input factors as well as further vehicle dynamic requests and transmits the request "Engage targeted gear" via the chassis CAN, CDI control unit or ME-SFI [ME] control unit and drive train CAN to the electronic transmission control control unit (transmission 722.6) or the fully integrated transmission control unit (mechanism 722.9). This request is, however, to be understood as a switching recommendation.

The back or upshift of the A/T takes place autonomously by the electronic transmission control control unit (transmission 722.6) or the fully integrated transmission control unit (transmission 722.9) itself, dependent on the current operating condition.

IMPORTANT For vehicles with code (233) DISTRONIC PLUS, code (237) Active Blind Spot Assist or code (238) Active Lane Keeping Assist, the video and radar sensor system control unit transmits the request "Engage target gear" via the chassis CAN to the Electronic Stability Program control unit.

Increase/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 responds by increasing or reducing the braking torque.

IMPORTANT For vehicles with code (233) DISTRONIC PLUS, code (237) Active Blind Spot Assist or code (238) Active Lane Keeping Assist, the video and radar sensor system control unit transmits the request "Increase/reduce brake torque" via the chassis CAN to the Electronic Stability Program control unit.

The cruise control function includes the following subfunctions:

Additional automatic speed control function requirements 

Function sequence for automatic speed control 

Through actuation of the "Resume from memory" switch the last specified speed stored is applied, provided a specified speed was stored since the last engine start. If no specified speed was stored, the current vehicle speed is set as the specified speed. The specified speed is displayed in the speedometer.

To do this the Electronic Stability Program control unit transmits appropriate information via the chassis CAN to the IC.

IMPORTANT For vehicles with code (233) DISTRONIC PLUS, code (237) Active Blind Spot Assist or code (238) Active Lane Keeping Assist the video and radar sensor system sends this information via the chassis CAN to the IC.

IMPORTANT The following events deactivate the automatic speed control:

The following activities are started to reach or hold the specified speed:

The driver also has the option to accelerate beyond the set specified speed through actuation of the accelerator pedal (for example when overtaking).

After removal of the acceleration request (release of the accelerator pedal) the set specified speed is regulated again.

Function sequence for SPEEDTRONIC 

The SPEEDTRONIC encompasses the following subfunctions:

D Function sequence for variable SPEEDTRONIC (without code (494) USA version) 

D Function sequence for permanent limiter 

Additional function requirements for variable SPEEDTRONIC (without code (494) USA version) 

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.

The following activities are started if the set limit was reached:

IMPORTANT If the cruise control lever is switched to the function variable SPEEDTRONIC, the automatic speed control is deactivated.

IMPORTANT The following events deactivate the variable SPEEDTRONIC:

Function sequence for permanent limiter 

The maximum speed of the vehicle can be limited in Operation steps of v = 10 km/h or 5 mph from v = 160 to 240 km/h or v = 100 mph to 150 mph.

Adjustment of the maximum speed takes in the "Settings", "Vehicle" and "Limitation (winter tires)" menu in the IC.

The IC transmits the set maximum speed via the chassis CAN to the Electronic Stability Program control unit.

IMPORTANT For vehicles with code (233) DISTRONIC PLUS, code (237) Active Blind Spot Assist or code (238) Active Lane Keeping Assist the IC sends the set maximum speed via the chassis CAN 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.

The following activities are started if the set maximum speed was reached:

REFER TO SYSTEM WIRING DIAGRAMS Electrical function schematic for cruise control (CC) Without code (233) DISTRONIC PLUS
Without code (237) Active Blind Spot Assist
Without code (238) Active Lane Keeping Assist		 PE30.30-P-2051-97FAA 
For code (233) DISTRONIC PLUS,
for code (237) Active Blind Spot Assist,
for code (238) Active Lane Keeping Assist		 PE30.30-P-2051-97FAB 
  Overview of system components for driver assistance systems   GF54.00-P-9998CE
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