Put quite simply cars have evolved over the years and no more so than in the last 20 years. Cars are now bristling with electronic equipment that keeps your car running at its best but also at its safest. Due to these new systems towing equipment has also had to evolve in line with the manufacturer changes and developments which has resulted in cars now been far more safer when towing than ever before.
When a car is towing a caravan or a trailer the vehicle itself is placed under extreme loads both on the chassis, the brakes, the drivetrain and the engine. With the invention of increased dynamic safety and control systems inside the car the car now needs to 'know' if its towing something to ensure that the occupants, and those around it, are given the safest possible options available to them.
With the dedicated wiring systems, or VSKs, once you connect the 7 or 13 pin plug into the towing socket at the rear of the car the car then senses that it is connected and towing an item. The car then switches on/off certain electronic systems dependent on the make of the vehicle. This is to ensure that the vehicle operates at its optimum level at any given moment whilst towing.