TPMSProAlbert
10-04-2013, 07:06 PM
Direct TPMS systems include small sensors that are installed inside each of the tires. These sensors accurately monitor tire pressure and continuously relay this information, via radio signals, to the vehicle's electronic control unit (ECU). If tire pressure falls below required limits, a warning light on the instrument panel alerts the driver about the problem.
Indirect TPMS systems use the vehicle's ABS system to calculate the difference in tire diameters and approximate tire pressure. An additional downside of indirect technology is that it can register a fault if all four tires are low (which often happens in cold weather) and will likely always indicate low tire pressure when driving on a spare tire (which may be of different diameter than other slightly worn tires).
Indirect TPMS systems use the vehicle's ABS system to calculate the difference in tire diameters and approximate tire pressure. An additional downside of indirect technology is that it can register a fault if all four tires are low (which often happens in cold weather) and will likely always indicate low tire pressure when driving on a spare tire (which may be of different diameter than other slightly worn tires).