PEUGEOT 508 Handbook page 152

Visibility
Rear wiper
Rear wiper selection ring:
If a significant accumulation of snow or
ice is present, or when using a bicycle
carrier on the boot, deactivate the
automatic rear wiper via the instrument
panel screen configuration menu.
150
park,
intermittent wipe,
wash-wipe (set duration).
Reverse gear
When reverse gear is engaged, the rear wiper
will come into operation if the windscreen
wipers are operating.
Programming
the function is activated or
deactivated via the instrument panel
screen configuration menu.
this function is activated by default.
Windscreen and headlamp
wash
F Pull the windscreen wiper stalk towards
you for a few seconds. the windscreen
wash then the windscreen wipers operate
for a fixed period.
the headlamp washers only operate when
the dipped beam headlamps are on and the
vehicle is moving.