Trailer Stability Program
, or TSP
, is an extension of the car safety system known as Electronic Stability Control
Electronic stability control is a computerized technology that may potentially improve the safety of a vehicle's stability by detecting and minimizing skids. When ESC detects loss of steering control, it automatically applies the brakes to help "steer" the vehicle where the driver intends to go...
, or ESC. It applies exclusively to trailers
A trailer is generally an unpowered vehicle pulled by a powered vehicle. Commonly, the term trailer refers to such vehicles used for transport of goods and materials....
A travel trailer or caravan is towed behind a road vehicle to provide a place to sleep which is more comfortable and protected than a tent . It provides the means for people to have their own home on a journey or a vacation, without relying on a motel or hotel, and enables them to stay in places...
. It is designed as an extension to ESC and, on vehicles that have TSP, provided a vehicle specific tow bar wiring kit is used, it is automatically turned on whenever a trailer plug is connected to the vehicle's towing socket. The system uses the information from the ESC sensors to monitor the movement of the towing combination and check for any "snaking" movements, and to control them before they become dangerous.
A trailer or caravan may start to snake dangerously for several reasons. Manner of driving, crosswind
A crosswind is any wind that has a perpendicular component to the line or direction of travel. In aviation, a crosswind is the component of wind that is blowing across the runway making landings and take-offs more difficult than if the wind were blowing straight down the runway...
s, speed, condition of the road surface and/or a badly laden caravan or trailer can cause problems. If any snaking starts, drivers may react by counter steering the vehicle or speeding up. Both of these are dangerous as they amplify the effect of the sway and may result in an accident.
The TSP system uses sensors mounted in the vehicle, called yaw sensors, to detect any snaking motion. The system will then brake the wheels of the vehicle independently of each other and may cut power to the engine, to counteract the sway and reduce the speed.
While this is happening, the driver will see the ESP light on the instrument display flash whilst the system controls the combination, and they should try to keep the vehicle on as straight a line as possible. Some vehicles will brake hard in order to reduce speed, a behavior the driver may not expect.