Gear Lever Switch
Gear Lever Switch
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 transmission selector switch is positioned in the front of the centre console of the vehicle. The gear selector switch is configured as a control unit in its own right. With the gear selector switch, instead of being actuated mechanically, the transmission is now actuated electronically.
NOTICE: Discontinuation of locks.
The following locks are discontinued for 09/2009:
- Selector lever interlock, transmission position R
- Selector lever interlock, transmission position D
A Check Control message is output instead.
The selector lever interlock in the manual gate is still available.
Brief component description
Gear selector switch with selector lever
The gear selector switch (GWS) consists of the control electronics circuit and the selector lever. The sensors for recording the gearshift lever position and for inhibiting inadvertent gearshifts are integrated in the control electronics.
The drive position engaged is shown on the function display regardless of the selector lever position.
The following positions can be selected with the selector lever:
- P: for Park
The function "P" is to be set by operating a separate button on the gear selector switch.
- R: for reverse gear
- N: for Neutral
- D: for Drive = automatic mode
- M/S:M for Manual mode = Steptronic; S for Sport program = automatic mode with sport characteristic curve
In this shift pattern diagram, the drive position engaged is shown by LEDs. The shift pattern is only displayed if the transmission control unit has implemented the driver's choice and has reported this state to the gear selector switch via the bus. The gear selector switch only displays what it has received from the transmission control unit. The selector lever position of the gear selector switch is detected by means of hall effect sensors without contact and forwarded via PT-CAN to the transmission control unit (EGS). For availability reasons, these signals are also forwarded via the PT-CAN2 to the EGS.
NOTICE: Discontinuation of locks.
The following locks are discontinued for 09/2009:
- Selector lever interlock, transmission position R
- Selector lever interlock, transmission position D
A lock prevents inadvertent shifts to position "R". To cancel the inhibitor, the brake pedal must be depressed and the release button on the selector lever must be pressed. In the gear selector switch (GWS), a total of 3 actuators are used for the 3 locks. An electric motor with downstream transmission is used for the automatic return from the manual gate into the automatic gutter as well as for locking the manual gutter. A bidirectional, spring-centered double magnet (solenoid) is used for the lock towards selector lever position "R". A single magnet (solenoid) with spring is used for the lock towards selector lever position "D".
The locks are only supplied with current after terminal 15 On. This ensures that in automatic mode no shift travel is inhibited by the actuators in the event of a fault developing.
System functions
Functional networking
The following system overview shows the functional networking using the example of F01. not illustrated: Functional networking with front electronic module (FEM), e.g. F30.
Engaging a drive position
To engage a drive position after engine start-up, the selector lever must be pushed / overpushed backwards or forwards. To engage the drive position R, alongside the brake control, the release button on the side of the selector lever must be pressed. Selector lever position "P" is dislocated from the gear selector switch by its own button When the P button is pressed and the "P" signal comes from the electronic transmission control (EGS): The green light-emitting diode (LED) for the start position in the functional display of the selector lever is controlled by the gear selector switch. The selector lever is monostable in automatic shift gate (automatic mode) and manual shift gate (manual mode). The selector lever always returns to its initial position. The gate change is bistable. The selector lever remains in the selected gate. It is only possible to change to the manual gate (selector lever position "M/S") from selector lever position "D". This is done manually and may be done at any time. If the P button is pressed or the parking lock is automatically engaged by the ignition and the selector lever switch is still in the manual gate ("M/S" selector lever position): An automatic activation of an actuator is effected, which resets the selector lever to the monostable initial position of the automatic shift gate (automatic mode).
Recording the selector lever position
The selector-lever position is picked up by means of sensors without contact and forwarded via PT-CAN to the transmission control unit (EGS).
- 7 Hall effect sensors record the selector lever position in the longitudinal direction of the vehicle
- 4 Hall effect sensors register the transverse direction of vehicle of the selector lever position
For availability reasons, these signals are also forwarded via the PT-CAN2 to the electronic transmission control (EGS).
Automatic return
When the selector lever is engaged in the manual gate (selector lever position "M/S"), "Automatic reset" resets the selector lever to the automatic gate (selector lever position "D"). An electric motor is used as the actuator for the automatic return. A camshaft driven by the electric motor presses a sliding piece against the selector lever. The slide returns the selector lever to the automatic gutter. If the selector lever is located in the manual gutter (selector lever position "M/S"), the actuator is not supplied with current. An electric pulse from the actuator releases the selector lever and resets it to the automatic gate. Activation is effected by the GWS control unit on the basis of the signal inputs from the electronic transmission control (EGS).
Notes for Service department
General notes
Parking lock emergency release
If the parking lock can no longer be released hydraulically, mechanical emergency release is possible. This allows the vehicle to be pushed or pulled in case of emergency. For the emergency release the mat in the left cup holder of the centre console must be removed. Included: Observe new emergency release from vehicle underbody.
WARNING: Do not tow away vehicle.
Only transport the vehicle on a loading platform. Otherwise damage may occur. Follow the instructions in the operating instructions.
WARNING: Engage parking lock again after towing away vehicle.
The parking lock must be engaged again after towing away the vehicle. If the parking lock is not engaged, there is a risk that the vehicle may roll away.
Special situations (functions in the EGS electronic transmission control)
Memory function for driving direction change
Driver's choice from gearshift lever position "D" to "R" or from "R" to "D"
- For driving speed less than 5 km/h:
The driver's choice is implemented by the electronic transmission control (EGS).
- For driving speed between 5 and 10 km/h:
The selector lever position "N" is engaged by the electronic transmission control. The display of the engaged drive position changes to the driver's choice selector lever position "D" or selector lever position "R". The driver's choice is stored. If the vehicle's speed drops below 5 km/h within 1 second, the driver's wish for selector lever position "D" or selector lever position "R" is carried out by the electronic transmission control. If the speed stays above this threshold, selector lever position "N" remains and the display changes to selector lever position "N".
- For driving speed greater than 10 km/h:
The selector lever position "N" is engaged by the electronic transmission control.
Memory function, parking lock
Driver's choice selector lever position "P" (parking lock)
- For driving speed less than 2 km/h:
The selector lever position "P" is engaged by the electronic transmission control (EGS).
- For driving speed between 2 and 5 km/h:
The current selector lever position remains. The driver's choice is saved. If a speed of 2 km/h is undershot within 1 second, selector lever position "P" is engaged by the electronic gearbox control.
- For driving speed greater than 5 km/h:
The driver's choice is not accepted. The current selector lever position remains. The Check Control message "Transmission position P only when vehicle at a standstill" is displayed.
Hold time of position "N"
For driving speed less than 2 km/h and engine off:
When the selector lever position "N" is engaged and the ID transmitter inserted, the hold time of selector lever position "N" starts for 30 minutes. While this information is being sent by the electronic gearbox control (EGS), the function display remains on and selector-lever position "N" lights up in the gearshift diagram. At the end of the hold time of the selector lever position "N" the display flashes: The electronic transmission control (EGS) engages the selector lever position "P" after 10 seconds. If the selector lever is moved during the holding time of position "N", the 30 minutes of the holding time for selector-lever position "N" start from the beginning.
We can assume no liability for printing errors or inaccuracies in this document and reserve the right to introduce technical modifications at any time.