Highlander Tire Pressure Monitoring - How does it work?

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My wife just got an '06 Highlander (4 Cyl, 2WD) and I'd like to put snow tires/rims on for the winter. I think the Tire Pressure Monitoring System works by comparing speed of each wheel to known speed of a properly inflated tire/wheel. Can anyone confirm this? I'm hoping that the car does not have sensors built into the stock rims. Thanks for any replies - no one at the dealer was sure. [Cheers!]
 
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The footnote quoted below appears in the vehicle brochure. Click this link and click the "CREATE eBROCHURE" button. This tells me it's using the wheel speed sensors to detect differences in tire rotation. It won't tell you an exact pressure, just when one is noticably different than the others. If it used actual pressure sensors like GM's newer systems, they wouldn't give this warning.
quote:
Toyota's Tire Pressure Monitor alerts the driver when tire pressure is critically low. For optimal tire wear and performance, tire pressure should be checked regularly with a gauge; do not rely solely on the Monitor. See your Owner's Manual for details.
Edit: BTW, pressure sensors are usually incorporated into the valve stems. They shouldn't impede snow tire installation more than any other valve stem.
 
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having done tire work on these vehciles i can tell you exactly how it works, seeing as how i damaged a pressure moniter and had to buy a new one. take a close look at the valve stem, notice how it is metal and not rubber. that is your pressure moniter. it sends a signal to a receiver that give the PCM the pressure. it will turn the light on when one of the tires drops below a threshold compared to the others, it can also come on if all the tires are too low. nothing involves the wheel speed sensor that i know of. one advantage to this is that when you air up the tires, there is a metal stem, so theres no annoying flex, and nothing to have a punk kid slice. just found some good info on a Prius webpage. http://www.buyfordracing.com/shop/product_info.php?products_id=262
 

oily boyd

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Thanks for the replies, guys. I am embarassed to say that the answer is revealed in the owners manual. [Roll Eyes] Briefly, the low pressure warning system may malfunction if: - a compact spare is mounted, the vehicle is being driven on slippery roads or the tread wear is very different among tires; even though inflation is correct. - The vehicle speed is < 19mph or >62 mph and driving duration is < 5 minutes. - Tire manufacturer or tread patterns differ. So, the 06 Highlander IS using wheel speeds to calculate the comparative tire pressures. I confirmed that the valve stems are indeed rubber/plastic. I believe the Prius does have the valve stem transmitters. Sorry for the wasted Bandwidth.. I hope this helps someone! Thanks for both of your replies.
 
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thats strange. i guess im used to the other toyotas i see with the metal stems. i actually broke one on a tundra when i was changing tires on it. strangely though, the toyota dealer keeps them in stock.
 
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The bandwidth wasn't at all wasted IMHO. At least now we know how the Highlander's tire pressure monitoring works. Also, when a vehicle has the special valve stems, there should be a way to get the vehicle to display the exact pressures (at least all GM's systems do and I can't imagine Toyota being different) and the manuals won't carry warnings about the system's limitations. If it just pops a low pressure warning, but won't give a pressure, that's a good clue.
 
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