Gear selector switch (GWS)

The gear selector switch (GWS) enables selection of a drive position of the automatic gearbox with Steptronic mode and Sport program. The GWS is positioned in the front area of the centre console of the vehicle and is designed as a separate control unit.

Brief description of components

The GWS consists of function geometry (housing) and gear lever with integrated function display. The Sport button (EDC button) is integrated in the GWS and it can be replaced separately.
Independently of the selector-lever position, the engaged drive position is displayed in the function display.
The selector-lever position of the GWS is picked up by means of sensors without contact and forwarded via PT-CAN to the gearbox control (EGS). For reasons related to availability, these signals are also passed on across a LIN bus to the EGS.
The function display in the selector lever is designed as a shift diagram, showing the positions P, R, N, D, M/S. The engaged drive position is indicated in this shift diagram by means of LEDs. The display in the shift diagram only changes when the EGS has implemented the driver request and the GWS has confirmed this status via the bus.

Functionality of GWS

To engage a drive position after engine start-up, the selector lever must be pushed / overpushed backwards or forwards. One touch or pulling the selector lever always means N or no reaction.

To engage the drive position R, alongside the brake operation, the unlock button on the side of the selector lever must be pressed.

P is removed from the shift diagram by means of a separate button in the selector lever. When the P button is activated and 'P engaged' signal comes from the EGS, the green LED in the P button and the green LED for the start position in the shift diagram are activated by the GWS.

The GWS is mono-stable within the automatic gutter and within the Steptronic gutter, i.e. it keeps returning perceptibly to its initial position.
The gutter change is bi-stable. The gutter change into the manual gutter M/S from position D can be carried out manually at any time. There can be no gutter change from other positions.

If the P button is operated or P is automatically engaged by 'ignition off' and the GWS is still in the manual gutter (M/S), an actuator is automatically activated to return the selector lever to the mono-stable initial position of the automatic gutter.

The forward direction of movement of the selector lever towards and to the left towards M/S must be perceptibly blocked or released depending on initial position and status of the unlock button.

• A movement to the left into the manual cutter is only possible from position D.
  
• One touch forwards without the unlock button being operated is only possible from D or the mono-stable position of the selector lever
  
• One touch forwards with the unlock button operated is also possible from N.
  
• One touch backwards is always possible
  
• Overpressing forwards is only possible with the unlock button operated and only from the positions D, N and the mono-stable position of the selector lever.
  
• Overpressing backwards is always possible
  

The blocks only become active with terminal 15 and are deactivated in the idle state.

Special situations (functions in the EGS)

Memory function for driving direction change

Driver request from D to R or from R to D

• At v ≤ 5 kph, the driver request is implemented by the EGS
  
• At 5 ≤ v ≤ 10 kph, position N is engaged by the EGS. The position indicator switches to the driver request D or R. The driver request is stored. If a speed of 5 kph is undershot within 1 second, the driver request D or R is implemented by the EGS. If this speed is not undershot, position N remains display switches to N
  
• At v > 10 kph, N is engaged by the EGS
  

Memory function, parking lock

Driver request P

• At v ≤ 2 kph, P is engaged by the EGS
  
• At 2 ≤ v ≤ 5 kph, the current gearbox position remains; the driver request is stored. If a speed of 2 kph is undershot within 1 second, P is engaged by the EGS.
  
• At v > 5 kph, the driver request is not accepted. The current gearbox position remains and the CC message ”gearbox position P only at a standstill” is displayed
  

N holding phase

If position N is engaged at v ≤ 2 kph and engine off and the identification sensor is inserted, the N holding phase starts for 30 minutes. While this information is sent by the EGS, the display remains on and N lights up. At the end of the holding phase, the display flashes and the EGS engages P after 10 seconds (Auto P). If the selector lever of the GWS is moved during the N holding phase, the 30 minutes of the N holding phase start from the beginning.