It was loaded by the inflation pressure decision device and

摘要

PROBLEM TO BE SOLVED: To prevent erroneous determination in determining the presence or absence of a decrease in tire pneumatic pressures even if a change is applied to a factor causing an effect on a resonant phenomenon due to the coupled vibration of a tire and a suspension. ;SOLUTION: A ROM 300 beforehand stores m pieces of alarm threshold values used for determining the presence or absence of a decrease in tire pneumatic pressures. When an alarm threshold value selecting part 240 receives instructions on changing the selective threshold value from a jig 700 specialized for changing the threshold value, determination is made that selective threshold value change conditions have been established. When the alarm threshold value selecting part 240 receives instructions on number i corresponding to the alarm threshold value Ki to be changed, the threshold value selecting part 240 accepts the number i to write the number i in an EEPROM 400. Next, when a vehicular ignition switch is in an 0N state, an alarm threshold value reading part 230 reads the number i from the EEPROM 400 and reads out the alarm threshold value Ki corresponding to the number i from the ROM 300. The result selects the alarm threshold value Ki as a new selecting threshold value.;COPYRIGHT: (C)1999,JPO