Gear operating switch (F191)
The gear operating switch is installed in the gearshift knob and detects vertical movement along the gearstick.
When Ecomatic mode is switched off, because the clutch is not opened when the accelerator pedal is lifted, this switch is relied upon to tell the Digiswing control unit to open the clutch as it senses the pressure on the gearstick that you are trying to disengage or engage a gear. Without this switch it would be unable to determine that a gear is trying to be selected or deselected.
This switch is also required when trying to engage or disengage first or second gear from neutral at a stand. For example, if the vehicle has previously been switched off in a gear to prevent it rolling away, even when the ignition is on, the clutch will remain closed to prevent the car rolling off, a vehicle start is not possible with a gear engaged for obvious reasons, and so to select neutral without trouble the clutch needs to be opened, hence relying on this switch for information.
This switch is also used partially in Ecomatic mode, from my own research if this switch is activated, the Load signal potentiometer (G157) threshold (in percentage) is increased slightly to allow an earlier opening of the clutch, this can be used to eliminate clutch opening delay in 1st gear.
Additionally, according to the sales brochure, this switch was also meant to disable the engine from switching off in Ecomatic mode when pressure was being applied, however it seems this feature was not implemented, or that they were confusing horizontal movement of the gear lever (i.e., between neutral gate 1-2 and 3-4) which is indeed detected and delays a gear shift.