Dear Car Talk:
I have an ‘07 Chevy Tahoe. I had an ‘02 prior to this one, and it was indestructible. The ‘07 has an issue that no one can figure out. This sounds ridiculous, but I’ve got witnesses who have driven it and have had the same experience. When I drive my Tahoe in the snow, it bucks and bangs and sounds like a piston is going to come up through the hood — but only in frozen precipitation! This does not happen in the rain or in nice weather, only when it’s snowing. What the heck? — Courtney
They all do that, Courtney.
I think what you’re experiencing is the traction control working. The traction-control system is tied into the truck’s antilock braking system (ABS). When the computer senses that a wheel is slipping (like wheels often do in snow and ice), the computer uses the ABS to apply the brake on that one slipping wheel — many times per second. The idea is to keep the wheel from spinning, at which point it loses its grip on the road and allows the vehicle to skid.
Anyway, ABS can be pretty noisy. It can sound a lot like bucking, chattering and banging, and maybe even like a piston is going to come through the hood (that’s probably the ABS pump you hear). You’ll also feel the chattering in the brake pedal and steering wheel.
Now, if this is a constant noise, and the traction control is continuously operating while you drive, there may be something wrong with it. You could have one or more bad sensors. But normally that will turn on the ABS warning light. So I’m guessing it’s operating normally, and kicking in only when one of your wheels starts to spin.
Here’s how you test it: Pull out your owner’s manual. That’s that thing gathering dust in the back of your glove compartment, behind the gas receipts and the empty packs of Dentyne. Look up “Traction Control” in the index, and find out where the “Traction Control Off” button is on your Tahoe. Then, next time you experience this effect, turn off the traction control.
If the noises stop during acceleration and you slide toward the guard rail, you’ll know it was the traction control working. Note that even when you turn off the traction control, the ABS still will operate if a wheel skids when you’re stopping.
If you believe the noises really are continuous while you’re driving in snow, rather than intermittent, then next time it snows or sleets, stop by the Chevy dealer and ask a service guy to take a ride with you. My first guess is that he’ll tell you that what you’re hearing is the traction-control system doing its job. My second guess is that he’ll try to sell you a 2018 Tahoe anyway. Good luck, Courtney.
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