08 Starting and driving
Hill Descent Control (HDC)*13
The function only operates in first gear posi-
tion and in reverse gear. For an automatic
gearbox, gear position 1 must be selected,
which is shown with the figure 1 in the com-
bined instrument panel, see Automatic gear-
box -- Geartronic* (p. 274).
WARNING
HDC can be compared to an automatic
engine brake. When you release the accelera-
tor on downhill gradients the car is normally
braked by means of the engine striving for low
engine idling speeds, so-called engine brak-
ing. But the steeper the roadway and the
more load in the car, the faster the car coasts
despite engine braking - the HDC function
compensates for this with automatic brake
intervention.
HDC does not work in all situations but is
designed merely as a supplementary aid.
The driver always bears ultimate responsi-
bility for ensuring that the vehicle is driven
safely.
NOTE
Function
HDC cannot be activated on an automatic
gearbox when the gear selector is in posi-
tion D.
General information on HDC
Operation
HDC makes it possible to increase/reduce
speed on steep downhill gradients, with a
foot only on the accelerator pedal, without
using the foot brake. The sensitivity of the
accelerator pedal decreases and becomes
more precise by means of the full actuation of
the pedal being restricted to adjusting engine
speed within a limited range. The brake sys-
tem brakes itself and provides the car with a
low and even speed, so allowing the driver to
fully focus on steering.
HDC allows the car to roll at a maximum of
10 km/h (6 mph) forwards with engine braking
and 7 km/h (4 mph) backwards. However, any
speed within the gear's speed register can be
selected using the accelerator pedal. When
the accelerator pedal is released, the car is
braked quickly to 10 or 7 km/h (6 or 4 mph)
respectively, irrespective of the hill's gradient
and without the need for the foot brake.
HDC On/Off.
HDC is activated or deactivated with one of
the centre console's switches. The lamp
within it illuminates when the function is acti-
vated.
The brake lights come on automatically when
the function is operating. The driver can brake
or stop the car at any time by using the foot
brake.
HDC is particularly helpful on steep gradients
with an uneven road surface and slippery
sections. E.g. when launching a boat on a
trailer from a ramp.
When HDC is operating, the combined
instrument panel's symbol illuminates
combined with the text message Hill
descent control ON.
HDC is deactivated:
08
13
Only possible on the XC70 AWD.
282
* Option/accessory, for more information, see Introduction.
English 
