Mercedes-Benz SL 2015 Owner's Manual page 185

Driving systems
182
From the:
sixth segment onwards, you will hear an inter-
R
mittent warning tone for approximately two
seconds.
seventh segment onwards, you will hear a
R
warning tone for approximately two seconds.
This indicates that you have now reached the
minimum distance.
Deactivating/activating PARKTRONIC
Deactivating/activating PARKTRONIC
:
Indicator lamp
;
If indicator lamp ; lights up, PARKTRONIC is
deactivated. Active Parking Assist is then also
deactivated.
i
PARKTRONIC is automatically activated
when you turn the key to position 2 in the
ignition lock.