TIRE AIR PRESSURE MONITORING DEVICE AND INITIALIZATION METHOD OF TIRE AIR PRESSURE MONITORING DEVICE

PROBLEM TO BE SOLVED: To automatically carry out initialization operation after air pressure adjustment in a tire air pressure monitoring device. SOLUTION: An alarm determination part 118 determines abnormal air pressure when tire air pressure is reduced by a preliminarily defined ratio relative to set pressure. A data holding part 106 holds the tire air pressure detected by an air pressure sensor when the ignition of a vehicle is turned off and on about each wheel. An initialization determination part 108 calculates the variation amount of the tire air pressure of each wheel between ignition-off and ignition-on. When a variation amount is not smaller than a preliminarily defined threshold, the variation of the tire air pressure is determined to be due to intentional adjustment. An initialization part 112 resets the set value of the data holding part 106 when the tire air pressure is determined to be intentionally adjusted. COPYRIGHT: (C)2008,JPO&INPIT