Tire Monitoring System: Description and Operation

The Low Tire Pressure Warning System (LTPWS) consists of a Low Tire Pressure Indicator Module Assembly and four unique LTPWS Sensor Assemblies. The sensors are composed of a power source, a pressure detector and a radio transmitter.

When the Ignition Switch is turned to "RUN," voltage is applied to the Low Tire Pressure Indicator Module Assembly. The module will test "LOW TIRE PRESSURE" and "SERVICE LTPWS" Indicators by lighting them for approximately two seconds.

While the vehicle is moving, road vibrations are felt by the LTPWS Sensor Assemblies. The road vibrations excite a crystal in the LTPWS Sensor Assemblies which produces power for the sensors. Each LTPWS Sensor Assembly then transmits, via radio, a unique signal to the Low Tire Pressure Indicator Module Assembly. This signal indicates to the Low Tire Pressure Indicator Module Assembly that the LTPWS Sensor Assembly is present and operating. If the Low Tire Pressure Indicator Module Assembly fails to receive a signal from each of the sensors on a regular basis, it will set a malfunction code and light the "SERVICE LTPWS" Indicator.

The Low Tire Pressure Indicator Module Assembly will turn "OFF" the "SERVICE LTPWS" when it detects all four sensors are operating.

The LTPWS Sensor Assemblies can detect when tire pressure falls below approximately 25 psi. When the LTPWS Sensor Assembly detects a low tire pressure condition and road vibrations permit power up, the sensor will transmit a signal to the Low Tire Pressure Indicator Module Assembly indicating a low pressure condition. The Low Tire Pressure Indicator Module Assembly will then warn the driver by lighting the "LOW TIRE PRESSURE" Indicator. The Low Tire Pressure Indicator Module Assembly will not turn "OFF" the "LOW TIRE PRESSURE" Indicator until the Ignition has been recycled, even if the tires have been inflated to the proper pressures.