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

MODEL 166 up to model year 2016 

Cruise control function requirements 

• Engine running or drivetrain operational
• Gear range "D" engaged
• Vehicle speed v ≥ 30 to 250 km/h
• Vehicle speed with active distance control v ≥ 30 to 200 km/h (with code 233 (DISTRONIC PLUS))

Cruise control - general 

The CC function automatically regulates the vehicle speed as constant and automatically to the target speed set by the driver. To do this the CC function evaluates the operator requests of the driver and the current driving condition.

Evaluation of these variables takes place dependent both model and installed equipment by the following control unit:

• Electronic Stability Program control unit (without code 233 (DISTRONIC PLUS) and without code 237 (Active Blind Spot Assist) or without code 238 (Active Lane Keeping Assist))
• Video and radar sensor system control unit (with code 233 (DISTRONIC PLUS), code 237 (Active Blind Spot Assist) and code 238 (Active Lane Keeping Assist))

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 sends function-relevant requests via chassis CAN 1 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 function is activated over the resume from memory switch. Here the last stored or momentary vehicle speed is set as the set speed.

Using the switches "decelerate" and "set" and the switches "accelerate" and "set", the target speed can be altered in steps of v = 1 km/h or v = 10 km/h.

Actuation up to the actuation point increases the set speed by v = 1 km/h.

If the switch is pressed beyond the actuation point, the target speed is altered in steps of v = 10 km/h. If the switch is held at or beyond the actuation point, the target speed is altered every t = 0.6 s.

The following input factors are evaluated to implement the CC 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 or the ME-SFI [ME] control unit sends the "Engine running" or "Drivetrain operational" signal via chassis CAN 1 to the Electronic Stability Program control unit and, on vehicles with code (233) DISTRONIC PLUS, code (237) Active Blind Spot Assist or code (238) Active Lane Keeping Assist, additionally to the video and radar sensor system control unit.

Vehicle speed:

The vehicle speed is calculated on the basis of the wheel speeds. The rpm sensors detect the wheel speeds. The Electronic Stability Program control unit reads in the signals of the rpm sensors directly and sends them on vehicles with code (233) DISTRONIC PLUS, code (237) Active Blind Spot Assist or code (238) Active Lane Keeping Assist via chassis CAN 1 to the video and radar sensor system control unit.

Engaged gear range:

Information on the gear range is sent by the fully integrated transmission control unit via drive train CAN, CDI control unit or ME-SFI [ME] control unit and chassis CAN 1 to the Electronic Stability Program control unit and, on vehicles with code 233 (DISTRONIC PLUS), code 237 (Active Blind Spot Assist) or code 238 (Active Lane Keeping Assist), additionally 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 sends the control signals of the CRUISE CONTROL lever via chassis CAN 1 to the Electronic Stability Program control unit and, on vehicles with code 233 (DISTRONIC PLUS), code 237 (Active Blind Spot Assist) or code 238 (Active Lane Keeping Assist), additionally 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 reads in the signals from the accelerator pedal sensor directly and sends these via chassis CAN 1 to the Electronic Stability Program control unit and, on vehicles with code 233 (DISTRONIC PLUS), code 237 (Active Blind Spot Assist) or code 238 (Active Lane Keeping Assist), additionally to the video and radar sensor system control unit.

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

• Increase/reduce engine torque
• Engage targeted gear (back or upshift)
• Increase/reduce braking torque

Raise/reduce engine torque:

The Electronic Stability Program control unit evaluates the input factors as well as further driving dynamics requests and transmits the request "increase/reduce engine torque" via the chassis CAN 1 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 (233) DISTRONIC PLUS, code 237 (Active Blind Spot Assist) or code 238 (Active Lane Keeping Assist), the video and radar sensor system control unit sends the request "Increase/reduce engine torque" via chassis CAN 1 to the Electronic Stability Program control unit.

Engage targeted gear:

The Electronic Stability Program control unit internally evaluates the input factors as well as further driving dynamics requests and transmits the request "Engage targeted gear" via chassis CAN 1, the CDI control unit or the ME-SFI [ME] 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.

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 sends the request "Engage targeted gear" via chassis CAN 1 to the Electronic Stability Program control unit.

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.

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 sends the request "Increase/reduce braking torque" via chassis CAN 1 to the Electronic Stability Program control unit.

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 switched to passive (except model 166.074/874)
• ESP® not switched into "SPORT HANDLING MODE" (model 166.074/874)

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. To do this, the Electronic Stability Program control unit sends corresponding information via the chassis CAN 1, electronic ignition lock control unit and chassis CAN 2 to the instrument cluster.

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 sends this information via chassis CAN 1, electronic ignition lock control unit and chassis CAN 2 to the instrument cluster.

The following events deactivate the automatic speed control:

• Operation of the OFF switch

  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 on)

    Actuation of the SPEEDTRONIC LED takes place by the switchover logic integrated in the steering column tube module control unit.

  • ESP® not passively engaged (except model 166.074/874)
  • ESP® not switched into "SPORT HANDLING MODE" (model 166.074/874)
  • No "Kickdown" recognized

  Function sequence for variable SPEEDTRONIC (except 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)
  • Depressing the brake pedal
  • Active regulation of the ESP®
  • Speed v < 25 km/h
  • Gear range not "D"

  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 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 speed is regulated again after removal of the acceleration request (releasing the accelerator pedal).

• 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 vehicle speed v <20 km/h away from selected maximum speed)

Function sequence for permanent limiter 

The maximum speed of the vehicle can be limited in steps of v = 10 km/h from v = 160 km/h to 240 km/h. Adjustment of the maximum speed takes place in the menu "Settings", "Vehicle" and "Limitation (winter tires)" in the instrument cluster. The instrument cluster sends the set maximum speed via chassis CAN 2, electronic ignition lock control unit and chassis CAN 1 to the Electronic Stability Program control unit.

For vehicles with code 233 (DISTRONIC PLUS), code 237 (Active Blind Spot Assist) or code 238 (Active Lane Keeping Assist), the instrument cluster sends the set maximum speed via chassis CAN 2, electronic ignition lock control unit and chassis CAN 1 to the video and radar sensor system control unit.

Approximately v = 10 km/h before reaching the set maximum speed, a message appears in the multifunction display that indicates a maximum speed limitation.

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 166 up to model year 2016 without CODE 233 (DISTRONIC PLUS) without CODE 237 (Active Blind Spot Assist) without CODE 238 (Active lane keeping Assist)	PE30.30-P-2051-97NAA
		MODEL 166 up to model year 2016 with CODE 233 (DISTRONIC PLUS) with CODE 237 (Active Blind Spot Assist) with CODE 238 (Active lane keeping Assist)	PE30.30-P-2051-97NAB
	Overview of system components for driver assistance systems		GF54.00-P-9998GR