Volvo XC90 TWIN ENGINE Owner's Manual page 489

Related information
•
Trailer stability assist* (p. 487)
•
Checking trailer lamps (p. 488)
•
Towing capacity and towball load (p. 656)
•
Overheating in the engine and drive system
(p. 479)
•
Adverse driving conditions for engine oil
(p. 660)
7 Trailer Stability Assist
Electronic Stability Control
8
Trailer stability assist*
The function of trailer stability assist (TSA
stabilise cars towing trailers in situations where
they begin snaking. The function is included in
8
the stability system ESC .
Reasons for snaking
The snaking phenomenon can occur with any
car/trailer combination. Snaking normally occurs
at high speeds. But, there is a risk of it occurring
at lower speeds if the trailer is overloaded or the
load is improperly distributed, e.g. too far back.
In order for snaking to occur, there must be a
triggering factor, e.g.:
•
Car with trailer subjected to a sudden and
powerful side wind.
•
Car with trailer drives on an uneven road sur-
face or in a pothole.
•
Sweeping steering wheel movements.
If snaking has started, it could be difficult or even
impossible to suppress. This makes the car/
trailer combination difficult to control and there is
a risk that you could, for example, end up in the
wrong lane or leave the carriageway.
Trailer stability assist function
The trailer stability assist function continually
monitors the car's movements, particularly lateral
movements. If snaking is detected, the front
wheels are individually braked. This serves to sta-
7
) is to
bilise the car/trailer combination. This is often
enough to help the driver regain control of the
car.
If snaking is not eliminated the first time that
trailer stability assist intervenes, the car/trailer
combination is braked with all wheels and engine
power is reduced. Once snaking has been gradu-
ally suppressed and the car/trailer combination is
stable once again, the system stops regulating
and the driver once again has full control of the
car.
NOTE
The stability function is deactivated if the
driver selects Sport mode by deactivating
ESC via the menu system in the centre dis-
play.
Trailer stability assist may fail to intervene if the
driver uses severe steering wheel movements to
try to rectify the snaking because in such a situa-
tion the system cannot determine whether it is
the trailer or the driver causing the snaking.
STARTING AND DRIVING
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487
* Option/accessory.