The GS/EPS control unit (A16) analyzes the signals from the following components:
GS/EPS shift control unit (A15)
Gear sensor
Gate sensor
Splitter sensor
Range sensor
Clutch travel sensor
Transmission input rpm sensor
Speed sensor
The signals from other vehicle systems (e.g. ABS, ASR, drive control) which are available over the CAN bus, are also evaluated.
The GS/EPS control unit (A16) actuates the appropriate shift cylinders to match a driver command, the driving condition and the operational safety of the vehicle.
If the gearshift lever is actuated without the clutch, the driver command is stored for a period of 10 s and shown on the display as a gear preselection. If the vehicle is stationary and the parking brake applied or service brakes operated, the preselection remains stored for 2 minutes. In the case of incorrect operation or possible system damage, a warning signal is given and the driver request is canceled.
The "NOTEPS" output at the GS/EPS control unit (A16) prevents any voltage flowing to the shift contacts of the emergency switch.
If the "NOTEPS" voltage drops, the emergency shift contacts have a voltage applied to them and a separate ground connection is made for the solenoid valves through circuit 31.
If, however, the GS/EPS control unit (A16) detects a fault which does not necessarily authorize an emergency shift, the enabling of the emergency shift is prevented.