What is traction control and how does it work?

Traction control is a safety system fitted to most modern cars (it’s been a legal requirement in the UK since 2011) that helps to maintain traction between your car’s tyres and the road surface. Over the course of this article, we’ll take you through what it does, how it works, and whether it’s ever a good idea to switch the system off.

What does Traction control do?

In essence, the purpose of traction control is to eliminate – or at least significantly reduce – wheelspin. Wheelspin occurs when the level of turning force being applied to a wheel exceeds the level of friction that the tyre has on the road surface. If a wheel is spinning, it no longer has effective purchase on the road surface. In slippery driving conditions – such as rain, snow or ice – this can happen pretty easily, and all of a sudden.

You might associate wheelspin with trying to accelerate too hard, and indeed, traction control operates here to bring the driven wheels under control. However, wheelspin becomes more dangerous when it happens mid-corner, because it can make your car skid away from its intended steering line. A spinning front wheel can induce understeer (where the front end runs wide and doesn’t respond enough to your steering inputs), while a spinning rear wheel can induce oversteer (where the rear end steps out and tries to rotate more than it should). Both understeer and oversteer can be very dangerous on the road.

How does traction control work?

Your traction control system will automatically turn on when you turn your car’s ignition on, and will always be running in the background unless you make the conscious effort to switch it off (more on that later). As you drive, the system uses sensors on each wheel – the same ones used by the anti-lock braking system, or ABS – to monitor how quickly they’re spinning relative to each other, and relative to the speed of the car. If one wheel is spinning significantly faster than the others, then it has lost traction. Once wheelspin is detected, the system intervenes to slow down the spinning wheel by limiting power to that wheel, or by applying a small amount of braking to that wheel, or both. And it doesn’t matter whether your car is front-wheel drive, rear-wheel drive or all-wheel drive, the principle is the same.

The most modern and sophisticated traction control systems do this in such a subtle way, that you might not even be able to detect it intervening at all, except for a flashing traction control light on the dashboard (we’ll come back to this in a while) to show you that it is. With older or less sophisticated systems, you might feel a small hesitation in the power delivery, or a brief mechanical vibration underneath the car, a bit like the one you feel through the brake pedal when the ABS kicks in.

Like we said earlier, traction control has been a mandatory feature on all new cars in the UK since 2011, but it has been around in some form or another for much longer than that. The earliest systems began popping up in the 1970s, but these weren’t very effective, and the fact that they were only available on expensive high-end cars made them very rare. It was the early 1990s before these systems became much more finessed and widespread.

What does it mean if my traction control light comes on?

Remember that traction control light on the dashboard that we mentioned earlier? Conventionally, the symbol is usually in the shape of a car with two wiggly lines beneath it, and it’s usually illuminated in orange. In some cars, though, letters are used in place of this symbol: these might be TC, TCS, or something similar. And like we said earlier, if the light flashes on while you’re driving, it signifies that the system is intervening to help keep wheelspin at bay.

It’ll also illuminates when you first start your car to let you know that the system is operational, and then go out after a few seconds. However, if the light doesn’t go out and stays illuminated, it indicates that there’s a problem with the system, and you should get it checked out by a professional mechanic as soon as possible. Not only is it more dangerous to drive with faulty traction control, it also constitutes an MOT failure.

Can I switch traction control off?

You can, but we recommend that you don’t. It’s an important safety feature that makes the roads safer for everyone, and turning it off means you instantly run a greater risk of skidding. It doesn’t matter how good a driver you are, your traction control system will always react faster and more effectively to a potential skid than you can. You should certainly keep it switched on in slippery driving conditions.

However, the one instance where you might want to consider turning it off is when the conditions are so slippery that your car gets stuck, so in snow, ice or deep mud. If you’re trying to free a stuck car, a bit of wheelspin can be useful for gaining enough momentum to free the car.

If you do find yourself in this situation and need to turn your traction control off, this is usually done with a button found somewhere inside the cabin that carries the same symbol as the traction control light on the dashboard. Most cars require you to press and hold the button for a few seconds, and this is so that you don’t unintentionally disable the system if you brush the button accidentally. In more modern cars, turning the system off might be done within the menus of the infotainment system instead.

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