Technical Training

Cruise Control

Cruise control functions are activated directly by the multifunction steering wheel to the EMS. The individual buttons are digitally encoded in the MFL switch and are input to the EMS2000 over a serial data wire. Cruise Control is integrated into the EMS2000 because of the MDK/EDK operation.

- The EMS2000 controls vehicle speed by activation of the Electronic Throttle Valve (EDR).
- The clutch switch disengages cruise control to prevent over-rev during gear changes.
- The brake light switch and the brake light test switch are input to the EMS2000 to disengage cruise control as well as fault recognition during engine operation.

Road speed is input to the EMS2000 for cruise control. The vehicle speed signal for normal engine operation is supplied from the DSC module (right rear wheel speed sensor). The road speed signal for cruise control is supplied from the DSC module. This is an average taken from both front wheel speed sensors, supplied via the CAN bus.

Cruise control / multifunction steering wheel

With the aid of the multifunction steering wheel (MFL) the driver can operate various vehicle functions from the steering wheel. These functions include:

Radio functions

Cruise control functions

In addition to a high degree of comfort, the multifunction steering wheel also offers the driver increased safety, as it is not necessary to take the hands off the steering wheel to operate various functions. The driver can implement the functions from the multifunction steering wheel without diverting attention from the traffic situation.

The response times to multifunction steering wheel operations are so fast that there is no noticeable delay in the feedback.

For cruise control purposes, the signals for the cruise control function are sent from the multifunction steering wheel to the engine control module where they are evaluated. There is no separate cruise control module.

Cruise control (Tempomat) operation
The cruise control operating unit is fitted to the multifunction steering wheel. Description of operating keys:

Resume: The vehicle accelerates or decelerates from non-controlled operation to the driving speed last set and maintains this speed.

Accelerate (+): The speed is increased by 1 mph (1 km/h) by briefly hitting this button. If pressed longer, the speed is increased until the button is released again. Cruise control is only switched on, however, if all switch-on conditions are fulfilled. These switch-on conditions are:

Accelerate button in neutral position before switching on cruise control.

Minimum speed of 20 mph (30 km/h) must be exceeded.

The brake pedal must be in rest position.

The clutch pedal must be in rest position on vehicles with manual transmission.

Drive stage 2 to D must be engaged on vehicles with automatic transmission.

No switch-off condition must be active. Switch-off conditions are possible either by pressing the control elements (e.g. pressing the OFF button on the control panel) or they can arise as the result of detected fault statuses. The corresponding fault codes are stored in the fault memory.

Decelerate: The driving speed is reduced from the set cruise control by pressing the decelerate button on the steering wheel. The speed is decreased by 1 mph (1 km/h) by briefly hitting this button. If pressed longer, the speed is decreased until the button is released again. However, it is not possible for the driving speed to drop below the minimum set speed.
The deceleration function is terminated by a switch-off condition occurring:

Deactivation via main switch

Operating brake pedal

Operating clutch pedal (manual transmission)

Engaging drive stages or "P" or "N" (automatic transmission)

Off (I/0): Switching off cruise control (Tempomat) function. After switching the ignition lock to position 1 or 2, cruise control assumes standby mode by operating the main switch (I/0). Standby mode is a system preparation function (arming) that must be carried out before switching on the cruise control. It is intended to prevent the cruise control being switched on by unintentional operation of one of the controls. Tempomat standby is indicated by an LED in the instrument cluster. Following standby and after fulfilling all switch-on conditions, cruise control can be activated by pressing the acceleration button.