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Cruise control (CC), function - GF30.30-P-0001GV

MODEL 164.1/8, 251.0/1 as of model year 2009 

Fig 1: Cruise Control (CC) - Function Diagram
G10116078Courtesy of MERCEDES-BENZ USA

Function requirements, general 

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 (219) the Distronic (DTR) the DTR controller unit transmits function relevant requests via the vehicle dynamics CAN to the Electronic Stability Program control unit.

The Electronic Stability Program control unit processes this and prioritizes it according to a self evaluated parameter.

Operation of the CC function over the TPM push button, vehicles without code (494) USA version 

Fig 2: Identifying CC(TPM) Switch Adjustment Position On Vehicles Without Code 494
G10116079Courtesy of MERCEDES-BENZ USA

Operation of the CC function over the TPM push button, vehicles with code (494) USA version 

Fig 3: Identifying CC(TPM) Switch Adjustment Position On Vehicles With Code 494
G10116080Courtesy of MERCEDES-BENZ USA

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. 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 function: 

Engine running or drivetrain operational

The CDI control unit or the ME-SFI [ME] control unit transmits the "engine runs" signal or "drivetrain operational" via the engine compartment CAN to the ESP control unit (except model 164.195) or to the RBS control unit (for model 164.195) and for vehicles with code (219) Distronic (DTR) as well via the engine compartment CAN, ESP control unit and vehicle dynamics CAN to the DTR controller unit.

IMPORTANT In model 164.195 all acceleration, deceleration or shift requests from the CDI control unit or the ME-SFI [ME] control unit are coordinated. The CDI control unit or the ME-SFI [ME] control unit prioritizes the requests according to their relevance. Here additional variables are taken into account, for example the charge level of the high-voltage battery or requests from the comfort systems (for example AAC).

Engaged gear range:

The fully integrated transmission control unit (VGS) (except model 164.195) transmits information to the gear range via the engine compartment CAN to the ESP control unit (except model 164.195) and for vehicles with code (219) Distronic (DTR) additionally via the engine compartment CAN, ESP control unit and vehicle dynamics CAN to the DTR controller unit.

For model 164.195, the hybrid fully integrated transmission control controller unit transmits information about the gear range via the hybrid CAN, ME-SFI [ME] control unit and engine compartment CAN to the RBS control unit.

Vehicle speed:

The vehicle speed is calculated by the ESP control unit (except model 164.195) or from the RBS control unit (for model 164.195) from the wheel speeds.

For vehicles with code (219) the Distronic (DTR) the ESP control unit transmits the wheel speed signal also via the vehicle dynamics CAN to the DTR controller unit.

Driver request over the CC [TPM] push button

The steering column tube module reads in the driver requests via the TPM push button. The steering column tube module transmits the status of the TPM push button via the engine compartment CAN to the ESP control unit (except model 164.195) or to the RBS control unit (for model 164.195) and for vehicles with code (219) Distronic (DTR) also via the vehicle dynamics CAN to the DTR controller unit.

Accelerator pedal position:

The CDI control unit or the ME-SFI [ME] control unit transmits information about the accelerator pedal position via the engine compartment CAN to the ESP control unit (except model 164.195) or to the RBS control unit (for model 164.195) and for vehicles with code (219) Distronic (DTR) as well via the engine compartment CAN, ESP control unit and vehicle dynamics CAN to the DTR controller unit.

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

Increase/reduce drive torque:

For vehicles without code (219) Distronic (DTR) the ESP control unit (except model 164.195) or the RBS control unit (for model 164.195) evaluates the input factors as well as further driving dynamic requests and transmits the request "Raise/reduce drive torque" via the engine compartment 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 (219) the Distronic (DTR) the DTR control unit transmits the request "Raise/reduce drive torque" via the vehicle dynamics CAN to the DTR controller unit. The Electronic Stability Program control unit processes this and transmits it according to its priority via the engine compartment CAN to the CDI control unit or the ME-SFI [ME] control unit.

Engage targeted gear:

For vehicles without code (219) Distronic (DTR) the ESP control unit (except model 164.195) or the RBS control unit (for model 164.195) evaluates the input factors as well as further driving dynamic requests and transmits the request "Engage targeted gear" via the engine compartment CAN to the fully integrated transmission control unit (VGS) (except model 164.195) or via the engine compartment CAN, CDI control unit or ME-SFI [ME] control unit and HYBRID CAN to the fully integrated transmission control Hybrid controller unit (for model 164.195).

For vehicles with code (219) the Distronic (DTR) the DTR controller unit transmits the request "Engage targeted gear" via the vehicle dynamics CAN to the ESP control unit. The Electronic Stability Program control unit processes this and transmits it according to its priority via the engine compartment CAN to the CDI control unit or the ME-SFI [ME] control unit.

This request is however is only to be understood as a switching recommendation.

The downshift or upshift of the A/T occurs autonomously by the fully integrated transmission control unit (VGS) (except model 164.195) or by the Hybrid fully integrated transmission control controller unit (for model 164.195), dependent on the current operating condition.

Raise/reduce braking torque:

For vehicles without code (219) Distronic (DTR) the ESP control unit (except model 164.195) or the RBS control unit (for model 164.195) evaluates the input factors and actuates the traction system hydraulic unit.

For vehicles with code (219) the Distronic (DTR) the DTR control unit transmits the request "Raise/reduce brake torque" via the vehicle dynamics CAN to the DTR controller unit. The ESP control unit responds by actuating the traction system hydraulic unit.

The traction system hydraulic unit reacts by increasing or reducing the braking torque.

IMPORTANT For model 164.195 the kinetic energy is converted within defined limits through a generator into electrical energy (regenerative braking). If the required braking torque exceeds the deceleration through regenerative braking, then the regenerative braking system control unit also actuates the traction system hydraulic unit and therefore the service brake.

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 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 (219) Distronic (DTR) the ESP control unit (except model 164.195) or the regenerative braking system control unit (/) (for model 164.195) sends information via the engine compartment CAN to the instrument cluster.

For vehicles with code (219) Distronic (DTR) the DTR controller unit transmits this information via the dynamics CAN, ESP control unit and engine compartment CAN to the IC.

IMPORTANT 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 events deactivate the automatic speed control:

The following activities are started in order to reach or maintain the set speed:

View of instrument cluster for an activated CC 

Fig 4: Display Of Instrument Cluster For Activated CC
G10116081Courtesy of MERCEDES-BENZ USA

Function sequence for SPEEDTRONIC 

The SPEEDTRONIC encompasses the following subfunctions:

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

Function sequence for variable SPEEDTRONIC (without 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:

IMPORTANT If switching takes place on the variable SPEEDTRONIC on the CC push button, the automatic speed control is deactivated. The following events deactivate the variable SPEEDTRONIC:

View of IC for an activated variable SPEEDTRONIC (without code (494) USA version) 

Fig 5: Display Of IC For Activated Variable SPEEDTRONIC Without Code 494
G10116082Courtesy of MERCEDES-BENZ USA

Function sequence for permanent limiter 

The maximum speed of the veh. 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.

For vehicles without code (219) Distronic (DTR) the IC sends the set maximum speed via the engine compartment CAN to the ESP control unit (except model 164.195) or the RBS control unit (for model 164.195). For vehicles with code (219) Distronic (DTR) the IC sends the set maximum speed via the engine compartment CAN, ESP control unit and vehicle dynamics CAN to the DTR controller unit.

Approximately v = 10 km/h before reaching the set maximum speed a message appears in the instrument cluster multifunction display that indicates a maximum speed limitation. The driver can accelerate the vehicle up to the set maximum speed.

If the set maximum speed is reached, the following activities are started:

Electrical function schematic for cruise control (CC) MODEL 164.1/8 as of model year 2009 without CODE 219 (Distronic (DTR)) PE30.30-P-2051-97MAC
MODEL 164.1/8 as of model year 2009 with CODE 219 (Distronic (DTR)) PE30.30-P-2051-97MAD 
MODEL 251.0/1 as of model year 2009 without CODE 219 (Distronic (DTR)) PE30.30-P-2051-97RAA
MODEL 251.0/1 as of model year 2009 with CODE 219 (Distronic (DTR)) PE30.30-P-2051-97RAB
Overview of system components for driver assistance systems   GF54.00-P-9998GV
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