Volvo XC90 2018 Owner's Manual page 472

STARTING AND DRIVING
Trailer stability assist*
The function of trailer stability assist (TSA
to stabilise cars towing trailers in situations
where they begin snaking. The function is
included in the stability system ESC
Reasons for snaking
The snaking phenomenon can occur with any
car/trailer combination. Snaking normally occurs
at high speeds. However, there is a risk of it
occurring at lower speeds if the trailer is overloa-
ded 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-
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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.
24 Trailer Stability Assist
Electronic Stability Control
25
470
Trailer stability assist function
The trailer stability assist function continually
24
) is
monitors the car's movements, particularly lateral
movements. If snaking is detected, the front
wheels are individually braked. This serves to sta-
25
.
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.
When Trailer Stability Assist
(TSA) is operating, the ESC
symbol flashes in the driver dis-
play.
Related information
Driving with a trailer (p. 468)
•
Electronic stability control (p. 287)
•
* Option/accessory.