Trailer stabiliser - TSA1

The trailer stability assist (TSA - Trailer Stability Assist) function is designed to stabilise the car and trailer combination if it begins to snake.

The trailer stability assist is included in the stability and traction control system (DSTC - Dynamic Stability and Traction Control).


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 (70-90 km/h) 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 surface 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.

The trailer stability assist continually monitors the car's movements, particularly lateral movements. If snaking is detected, the front wheels are individually braked. This serves to stabilise 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 the trailer stability assist comes into action, the car/trailer combination is braked with all wheels and engine power is reduced. Once snaking has been gradually 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. For more information, see Stability and traction control system (DSTC) - operation


The trailer stability assist can engage within the speed interval 60-160 km/h.


TSA function is switched off if the driver selects Sport mode, see Stability and traction control system (DSTC).

The trailer stability assist may fail to engage if the driver uses sudden steering wheel movements to try to rectify the snaking because in such a situation the system cannot determine whether it is the trailer or the driver that is causing the snaking.

Symbol stabilitetssystem - text

When the trailer stability assist is working, the combined instrument panel's DSTC symbol flashes.

  1. 1 Included in the installation of Volvo genuine towbar.