Basing tire pressure measurements on wheel rotational speed is referred to as an indirect system, and according to Wikipedia: "Audi is the first car maker to attempt to comply with the U.S. TPMS legislation using an indirect system, with the launch of the Audi A6 model year 2009. Since its introduction NHTSA has tested the system, however an official report of conformity with a PASS/FAIL assessment is yet to be released. There are many reservations on whether or not this system complies with the regulation, by admission of Audi themselves in the vehicle's owners manual there are several scenarios in which proper performance of the indirect TPMS system is not guaranteed (like sporty driving or winter conditions and many others), however Audi is confident that the car is able to pass the regulation test procedure. Unfortunately for Audi the test procedure, as stated on the document itself, is not enough to guarantee compliancy with the regulation, but this is up to NHTSA to assess." The requirements of the TREAD act are fairly loose, but I didn't think one could meet them with an indirect system. Indirect sensors appear to be used more widely in Europe. Perhaps they have easier to meet standards. It will be interesting to see the outcome of the Audi testing. On Tue, Aug 31, 2010 at 11:37 AM, Herbert Graf wrote: > On Mon, 2010-08-30 at 15:55 -0400, M. Adam Davis wrote: > >> The mandated tire pressure sensor program requires that every single >> new vehicle sold in the US contain a radio receiver (for tire pressure >> sensing) that ultimately feeds data into the main vehicle data network >> (which sits alongside the body and engine controllers). > > Are you sure about that? My understanding is there has to be a "flat > tire" monitor, but not that it has to specifically be a radio based > solution. > > My car uses the ABS sensors to detect a different rotation speed to > alert the driver of a flat, is this solution not good enough? > > TTYL > > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist > --=20 http://chiphacker.com/ - EE Q&A site --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .