Tire pressure sensor

The tire pressure sensor consists of a pressure sensor, rotary sensor (roll switch), control section, transmitter/receiver, battery and air valve.

Each tire pressure sensor is assigned with an individual ID code. It identifies the sensor condition and outputs it as the function code which is used for TPMS control module to judge whether the tire pressure sensor is operating properly or not. The tire pressure detected by the tire pressure sensor, along with the ID code and function code, is transmitted to the TPMS receiver on the radio wave. As the tire revolves (at a vehicle speed of approximately 32 km/h or more), the pressure sensor transmits the data at 1 minute intervals to TPMS receiver (active mode). However, when 15 minutes have elapsed after the vehicle is stopped (the tire is not revolving (the vehicle speed is less than approximately 11 km/h)), the data is sent to the TPMS receiver once an hour so as to prevent consumption of the battery (pause mode). Whether the tire is revolving or not is detected by the rotary sensor (roll switch).

There are 6 function codes that represent tire pressure sensor state as follows.

• Normal:

  The vehicle is at a stop other than Learn, OFF, Re-measure and Wake or is running.

• Learn:

  The tire pressure sensor is in the mode to register the ID code to TPMS control module.

• Re-measure:

  The tire pressure has changed beyond the range of ±8.4 kPa after a specified time, or the air in the tire is overcharged (349.35 kPa or more)

• Wake:

  The tire pressure sensor has changed from the pause mode to the active mode.

• OFF:

  The tire pressure sensor is in the data transmission stop mode (new one)

• Low battery:

  The battery voltage has reduced.