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Stewie
04-24-2008, 03:42 PM
I have an '07 Camry and the tire pressure light came on when I left work today. When I got home the pressure was 19 psi. I just aired them up Sunday to the recommended pressure, so I knew something was wrong. I ran up to Tire Town and sure enough there was hole in the tire.

My question is: How does the car know when the tire pressure is low? There are no internal sensors to measure pressure. Is there something external that measures distance to the ground or something? I can't figure any other way.

Bob Dole
04-24-2008, 03:48 PM
Indirect systems use the vehicle's antilock braking system's wheel speed sensors to compare the rotational speed of one tire vs. the others. If one tire is low on pressure, it will roll at a different number of revolutions per mile than the other three tires, and alert the vehicle's onboard computer.

luv
04-24-2008, 03:50 PM
Indirect systems use the vehicle's antilock braking system's wheel speed sensors to compare the rotational speed of one tire vs. the others. If one tire is low on pressure, it will roll at a different number of revolutions per mile than the other three tires, and alert the vehicle's onboard computer.

That's pretty cool.

Stewie
04-24-2008, 03:51 PM
Indirect systems use the vehicle's antilock braking system's wheel speed sensors to compare the rotational speed of one tire vs. the others. If one tire is low on pressure, it will roll at a different number of revolutions per mile than the other three tires, and alert the vehicle's onboard computer.

That makes perfect sense. Thanks.

ILWarpaint
04-24-2008, 03:57 PM
Ford's have a sensor banded to each wheel.

Stewie
04-24-2008, 04:02 PM
Ford's have a sensor banded to each wheel.

Is that like my bicycle's speed sensor that responds to a marker on the wheel?

REDHOTGTO
04-24-2008, 04:14 PM
i've never heard of that , cool
my avalanche has a sensor that is part of the valve, it measures the pressure and tells the computer what it is