Brake light switch (F)
The brake light switch sends information to the Digiswing control unit about whether the brake pedal is pressed. As far as I know this switch is used to tell the control unit to open the clutch earlier when the brake pedal is depressed in engine braking mode (Ecomatic off). I suspect it has no relevance on clutch or engine operation in Ecomatic mode.
I have confirmed this, the point of clutch operation (opening) is at a higher RPM when the brake pedal is depressed.
Forum discussion related to this: http://deylan.co.uk/golf/ecomatic/bbs/viewtopic.php?f=6&t=8