Trailer Stability Assist*
Causes of fishtailing
The phenomenon where a car with a trailer starts to fishtail may occur for all car-trailer combinations. High speeds are normally required for this to occur. But if the trailer is overloaded or the load is distributed incorrectly, e.g. too far back, there is a risk of fishtailing even at lower speeds.
Factors causing fishtailing may, for example, include the following:
- A sudden strong gust of wind from the side affects the car with the trailer.
- The car with the trailer drives along an uneven surface or into a pothole.
- Violent steering wheel movements.
Once the car has begun to fishtail, it may be difficult or impossible to stop it doing so. This makes the vehicle combination difficult to control, with a risk of it ending up in the wrong lane or leaving the roadway.
Trailer Stability Assist function
Trailer Stability Assist constantly monitors the car's movements, particularly sideways. If fishtailing is detected, individual brake control takes place at the front wheels, which helps to stabilise the combination. This is usually enough to allow the driver to regain control of the car.
If the car is not brought back under control despite the initial input from trailer stability assist, all wheels are used in tandem to brake the vehicle combination and the electric motor's drive is reduced. When fishtailing has gradually been eliminated and the combination is stable again, the system stops exerting control and the driver regains full control over the car.
Note
Trailer Stability Assist may not intervene if the driver attempts to stop the car fishtailing by means of violent steering wheel movements, as the system is then unable to determine whether the trailer or the driver is causing the fishtailing.
When Trailer Stability Assist is operational, the ESC symbol in the driver display flashes.