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Folks, there has been talk here before about the TPMS and what the system is, and why it doesn't report actual pressure of each tire. In the Fall 2009 issue of Quattro Quarterly, Jim Benoit gives us the answer:
"A less complex system was introduced in 2005 in some models and is referred to as "low-line". Each wheel had its own battery operated sensor [in the tire valve], but only one antenna was used. The system did not know the location of each tire but only the ID number of each tire pressure sensor. It compared the actual value of the tire pressure to the stored value. if the value was lower, the warning light would illuminate. This system could only alert the driver that there was a tire that had low pressure but could not specify which one."
The new (2010 and beyond) indirect tire pressure monitoring system works differently:
"The system [ITPMS] determines pressure loss based on two principles: wheel radius analysis and wheel spectrum analysis. To simplify, the ABS sensors can determine tire pressure loss by measuring the change of tire rolling diameter and the change in tire vibration as the tire loses pressure."
An advantage here is not extra parts, and the system can report each tires pressure individually.
Hopefully this clears up some of the discussion regarding TPMS and its current state.
Why would Audi use a "low line" system when my 2006 Jeep Commander, a far cheaper vehicle, displayed individual tire pressures at all 4 corners (and was quite accurate)?
Furthermore, having just had to buy a second set of TPMS sensors for my '09 A5, I can vouch for the fact that they are NOT cheap! I got the best price I could find, about $188 for four sensors, but most places wanted considerably more, and that's just for the sensors.
(By the way, not knocking on Houston A5 as the original poster, I know he was just relaying Audi's excuse, but I'm not buying it!)
(By the way, not knocking on Houston A5 as the original poster, I know he was just relaying Audi's excuse, but I'm not buying it!)
I'm not sure I'd classify the article in the magazine as an "excuse". As far as I know, the author probably doesn't actually work for Audi, but is an enthusiast. He was merely relaying information.
Why would Audi use a "low line" system when my 2006 Jeep Commander, a far cheaper vehicle, displayed individual tire pressures at all 4 corners (and was quite accurate)?
Also, "low-line" is merely a term to covey a difference from a "high-line" system, which is more complex, and thus, has more parts that can fail.
10-17-2009, 10:29 AM
Tire Pressure Monitoring Clarification
