Cruise Control (Tempomat) Operation

Cruise Control (Tempomat) Operation
A keypad for cruise control operation is located on the right-hand side of the steering wheel. Description of operating keys from top to bottom:

- 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 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 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 or they can arise as the result of detected fault statuses. The corresponding fault codes are stored in the fault code 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 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 "P" or "N" (automatic transmission)
- OFF : 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.
- S_BLS (brake light switch)
- S_BLTS (brake light test switch)

The DME control unit evaluates the signals for the purpose of registering brake operation.

Function
The brake light switch switches to ground (B-), the brake light test switch to B+. The plausibility of both signals is checked.

The following table shows how the signals behave:






Troubleshooting
A fault code is stored if the signals are not plausible. Cruise control is deactivated as a result.