Gear monitor switch (F209)
The gear monitor switch is a supplementary switch which detects whether a gear has been properly engaged, if a gear is only partially engaged this informs the Digiswing controller about this state and the clutch is not closed until the gear is correctly engaged - the control unit then flashes the gear display control lamp K48 [k48].
If this switch fails, the clutch will close at a later stage as it allows the driver additional time to complete the gear change. This may result in the vehicle revving up then the clutch engaging harshly.
The effects mentioned above will be more pronounced in engine braking mode/Ecomatic mode off. After releasing the gearstick after changing gear, it may take 2-3 seconds before the clutch is engaged. This will not happen every time and no obvious pattern seems to exist. If the driver is extremely slow to change gears on the other hand, the vehicle will attempt to close the clutch without the gear being properly engaged. In Ecomatic operation, this switch appears to be relied upon less because the control unit has the more precise task of operating the clutch in accordance to the engine load (accelerator pedal position) by the driver. Why this could also not be relied upon in engine-braking mode in the absence of a working gear monitor switch is unknown.
A fault code will be set if the switch fails after a few miles of normal driving, the warning lamps on the instrument cluster will not flash.