Volvo C70 Owner's Manual page 127

Starting and driving
Detachable towbar (option)
Fitting the towball
– Remove the guard plug.
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– Ensure that the mechanism is in the
unlocked position by turning the key
clockwise.
– Check that the indicator window (3)
shows red.
If the window does not show red, press
in (1) and turn the locking wheel
anticlockwise (2) until you hear a click.