Dear Tom and Ray:
I live in Michigan, where Mother Nature constantly tries to do me in with her lake-effect snow and black ice. I recently purchased a 2010 Jeep, which is the first vehicle I've ever owned with a traction-control button. Why in the world would I EVER want to turn the traction control off? I quite enjoy having traction. Is there any downside to always having the traction control system on?
Ray: Normally, no. For the vast majority of your driving lifetime, Dan, the traction control should be on.
Tom: Traction control uses the anti-lock braking system to prevent your wheels from spinning when you accelerate. Because once the wheels start to spin, you lose all traction and lose directional control of the vehicle. You've probably experienced this phenomenon, often referred to as fishtailing.
Ray: So, why would you ever want to turn it off? The only reason would be if you're already stuck in a pile of snow, for instance. Sometimes the only way out of a parking space or a snowdrift is to "blast out." That means hitting the gas and letting the wheel spin until it digs down and grabs onto something.
Tom: Or rocking the car back and forth between drive and reverse until you can build up enough momentum to get over the hump of snow that's blocking you. Neither of those techniques always works, but sometimes it's your only hope. And traction control prevents you from using those techniques.
Ray: Right. With traction control on, as soon as a wheel starts to spin, the brake gets applied to that wheel, preventing you from blasting anywhere!
Tom: In fact, some cars' traction control systems are so sensitive that they can make a car stop dead in its tracks in the snow. It's happened with some Mercedes models we've tested, and with the latest Toyota Prius.
Ray: Right. If the car doesn't have perfect traction, some traction control systems just won't let the car move. In cases like that, you'd want to be able to turn off the traction control and then, as soon as you get going, turn it back on. And then (to answer your question) leave it on, Dan.
(Car Talk is a nationally syndicated column by automotive experts (and brothers) Tom and Ray Magliozzi. Write to them at the Car Talk Web site.)