Automotive Blogger

I don’t know about you, but I’ve never completely understood the difference between traction control and stability control, especially since some cars have both, some have one or the other, and some don’t have either. I looked it up, recently, and thought I’d share.

First, it’s important to understand traction control and stability control are not the same thing. Typically, at least on newer cars, traction control is an electro-hydraulic system designed to prevent traction-loss under excessive steering or throttling by the driver.
To do this, it shares actuators and sensors with the anti-lock braking system.

There is a list, actually, of what traction control can do:

1. Brake wheels (one or more)
2. Suppress the spark to the cylinders (one or more)
3. Reduce the fuel supply to the cylinders (again, one or more)
4. On drive-by-wire cars, it can close the throttle
5. On turbo-charged cars, it can actuate the boost control solenoid to reduce boost, which in turn reduces engine power

That’s all very well and good, but how does it apply to actual driving? Here are some examples:

• On street vehicles, traction control helps regulate throttle input to prevent spinning when accelerating in snow or on wet pavement.
• In race cars, it allows the greatest amount of acceleration possible without wheel spin, and maintains an optimum slip angle when drivers accelerate out of a turn.
• Off road, traction control can be used with or in place of mechanical locking differential, slowing spinning wheels with quick bursts of brake pressure, and providing more torque to non-spinning wheels, which makes controlling the vehicle easier.
• While cornering, helps prevent front-wheel drive cars from reaching the point where the wheels can’t steer and drive, or, if the wheels do lose their gripping ability, it can help keep the car stable. (In rear-wheel-drive cars, it can prevent oversteer.)

Traction control, by the way, can trace it’s roots all the way back to Positraction, a kind of limited slip differential used in older high-powered cars with rear wheel drive.

It should, however, never be taken for granted or allowed to encourage driving in dangerous conditions.