Car Talk

March 2003

Dear Tom and Ray:

I own a '99 Pontiac Grand Prix with traction control, which makes sense to have in the Midwest, my fair region. There is a button on the dash that allows me to turn it off, should I desire to do so. I travel and rent cars frequently, and I've noticed that other makes that have traction control have an on/off button as well. Why, in the name of Britney Spears' bare midriff, is this the case? Under what circumstances would the average driver turn it off, and would he or she know when the proper circumstances arise? I certainly don't! -- Larry

Beat up old car

TOM: Good question, Larry. High-school kids were finding it impossible to "do doughnuts" in the school parking lot with their dad's traction-control-equipped cars, so the automakers thoughtfully added an on/off switch.

RAY: Actually, the off switch is for situations where the traction control works too well. Traction control prevents the wheels from spinning when you accelerate. This prevents the driven wheels from breaking away and skidding.

TOM: But there are a few rare circumstances in which you might want the wheels to spin. One is if you're stuck in the snow. If you're stuck in the snow with the traction control on, here's what happens: The wheels will try to turn, they'll get no traction and they'll stop. So, in a situation like that, the traction control can prevent the wheels from turning at all. No traction, no power to the wheels!

RAY: So by turning off the traction control, you can allow the wheels to spin, and you can try to get out of the snow the old-fashioned way -- by rocking the car back and forth ... and digging a 2-foot hole under each wheel that you'll never get out of.

TOM: No; it's possible that by turning off the traction control, you can create a little momentum and blow out of a pile of snow. The same thing can happen in sand or mud, too.

RAY: But other than that, just leave the traction control on and let it do its job.

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