Tire Pressure Monitors (?)
in [Toyota]
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From: Ray O on 21 Jun 2010 00:15 "croy" <hate(a)spam.invalid.net> wrote in message news:qfbt16h4hmhd0u4de02htqg42b4f6n2mqe(a)4ax.com... > >>I seem to recall reading that the Federal Motor Vehicle Safety Standards >>(FMVSS) are written so that all vehicles will eventually have a direct >>tire >>pressure monitoring system (TPMS) using the sensors mounted on the valve >>stems. As you surmised, even if all tires are equally low, the direct >>system will still illuminate the warning light. The sensors have >>batteries >>and transmitters that have to be registered with the vehicle's TPMS, and >>some vehicles also monitor the spare air pressure. >> >>The advantage of an indirect system that uses the ABS sensors to monitor >>wheel RPM is that it is less expensive and easier to implement since no >>additional sensors are needed. The disadvantage of the indirect system is >>the problem with all tires equally underinflated and less accuracy. >> >>The disadvantages of a direct system is that the metal valve stem needs a >>gasket that is another potential source of leaks, the valve stem must have >>the valve stem cap installed to prevent corrosion of the sensor, the >>system >>is more complex and therefore a greater source of potential problems, >>fix-a-flat in a can products will mess up the sensors, and the wheels need >>more weight to balance since the sensor is heavier than a valve stem. > > I tried checking one of the wheels on my RAV4 by letting air > out to produce a remaining pressure of only 18 PSI. When I > turned the key switch on, the tire pressure warning light > came on as usual, but after the checkout period, it went > out. Does this seem right? Or do the wheels need to rotate > to get the sensor closer to the receptor? Or none of the > above? > > -- > croy The wheels probably need to rotate a few times for the warning light to illuminate. -- Ray O (correct punctuation to reply)
From: C. E. White on 21 Jun 2010 07:30 "Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote in message news:hviqc9$pjt$1(a)news.eternal-september.org... > > "croy" <hate(a)spam.invalid.net> wrote in message > news:d23m16hh55vk6oer0aknogr8p8avvmeff5(a)4ax.com... >> On a 2008 RAV4, what type of Tire Pressure Monitors were >> supplied from the factory (the owner's manual doesn't >> state)? >> >> -- >> Thanks, >> croy > > If the valve stems are rubber, the tire pressure monitor (TPM) system uses > the signal from the antilock brake wheel rotation sensors to monitor > pressures. If the valve stems are metal, it uses a sensor mounted at the > end of the valve stem inside the wheel. > -- > > Ray O My SO 's RAV4 and both of my Sister's RAV4's (2007 and two 2008's) all have the valve stem sending units. The spares have one also. I thought the metal valve stem was a 100% predictor of valve stem tire pressure monitors until I had problems with a tire pressure sensor on my Ford truck. It has rubber valve stems so I assumed it either used the wheel speed sensors to determine that a tire had low pressure or it had a sensor strapped to the center of the wheel. In fact, it has valve stem tire pressure sensor, but they have rubber stems. They look just like the regular rubber valve stems. Ed
From: C. E. White on 21 Jun 2010 07:42 Try reading the info here: http://www.toyotatpms.com/ http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=44& http://www.artsautomotive.com/maintenance-faq/81-tpms-tire-pressure-monitoring-system http://www.tomorrowstechnician.com/Article/1614/tire_rack_offers_answers_to_top_five_tpms_questions.aspx Ed "croy" <hate(a)spam.invalid.net> wrote in message news:qfbt16h4hmhd0u4de02htqg42b4f6n2mqe(a)4ax.com... > >>I seem to recall reading that the Federal Motor Vehicle Safety Standards >>(FMVSS) are written so that all vehicles will eventually have a direct >>tire >>pressure monitoring system (TPMS) using the sensors mounted on the valve >>stems. As you surmised, even if all tires are equally low, the direct >>system will still illuminate the warning light. The sensors have >>batteries >>and transmitters that have to be registered with the vehicle's TPMS, and >>some vehicles also monitor the spare air pressure. >> >>The advantage of an indirect system that uses the ABS sensors to monitor >>wheel RPM is that it is less expensive and easier to implement since no >>additional sensors are needed. The disadvantage of the indirect system is >>the problem with all tires equally underinflated and less accuracy. >> >>The disadvantages of a direct system is that the metal valve stem needs a >>gasket that is another potential source of leaks, the valve stem must have >>the valve stem cap installed to prevent corrosion of the sensor, the >>system >>is more complex and therefore a greater source of potential problems, >>fix-a-flat in a can products will mess up the sensors, and the wheels need >>more weight to balance since the sensor is heavier than a valve stem. > > I tried checking one of the wheels on my RAV4 by letting air > out to produce a remaining pressure of only 18 PSI. When I > turned the key switch on, the tire pressure warning light > came on as usual, but after the checkout period, it went > out. Does this seem right? Or do the wheels need to rotate > to get the sensor closer to the receptor? Or none of the > above? > > -- > croy
From: Ray O on 21 Jun 2010 23:33
"C. E. White" <cewhite3(a)mindspring.com> wrote in message news:hvnig8$f20$1(a)news.eternal-september.org... > > "Ray O" <rokigawa(a)NOSPAMtristarassociates.com> wrote in message > news:hviqc9$pjt$1(a)news.eternal-september.org... >> >> "croy" <hate(a)spam.invalid.net> wrote in message >> news:d23m16hh55vk6oer0aknogr8p8avvmeff5(a)4ax.com... >>> On a 2008 RAV4, what type of Tire Pressure Monitors were >>> supplied from the factory (the owner's manual doesn't >>> state)? >>> >>> -- >>> Thanks, >>> croy >> >> If the valve stems are rubber, the tire pressure monitor (TPM) system >> uses the signal from the antilock brake wheel rotation sensors to monitor >> pressures. If the valve stems are metal, it uses a sensor mounted at the >> end of the valve stem inside the wheel. >> -- >> >> Ray O > > My SO 's RAV4 and both of my Sister's RAV4's (2007 and two 2008's) all > have the valve stem sending units. The spares have one also. > > I thought the metal valve stem was a 100% predictor of valve stem tire > pressure monitors until I had problems with a tire pressure sensor on my > Ford truck. It has rubber valve stems so I assumed it either used the > wheel speed sensors to determine that a tire had low pressure or it had a > sensor strapped to the center of the wheel. In fact, it has valve stem > tire pressure sensor, but they have rubber stems. They look just like the > regular rubber valve stems. > > Ed > I learned something new today! -- Ray O (correct punctuation to reply) |