For a safe and correct operation of TSP is it essential that the vehicle system recognizes that a trailer is mounted. For this you need a vehicle specific wiring kit. When a universal wiring kit is fitted, or a vehicle specific wiring kit is fitted but not coded, the operating system does not recognize that a trailer is mounted and TSP does not work. The wiring kit does receive signals but does not return any communication.
Does the driver notice when TSP works? The system’s corrections are so subtle that they are unnoticeable to the driver. That is why it is so important that the driver can rely on a correctly fitted wiring kit.
In this video the comparison is made of a car with a caravan that is equipped with TSP (Volkswagen Tiguan) and a car with a caravan that is not equipped with TSP (Mazda CX5). The differences are obvious.