Tire Monitoring System: Description and Operation
TIRE MONITORING SYSTEM
Low Tire Pressure Warning Light and Chimes
This light and chimes warn you that the tire inflation pressure is low. This light comes on when the ignition switch is turned to the on position and goes off after a few seconds. This means the low tire pressure warning light is operating properly.
If the warning light does not go off, or comes on or blinks during driving, or the chimes sound, this indicates that tire inflation pressure is low. Make sure there is no flat tire. If the warning light comes on again even after air is put in the tires, a tire may still be flat.
If this warning light comes on, the action you must take is completely different depending on the type of tires used. You must understand how to distinguish tires between standard tires and run flat tires in order to operate your vehicle safely.
If you drive over about 180 km/h (112 mph) with the tires not inflated at the designated pressure for high speed driving, the warning light may turn on. If the tires are at the designated pressure for ordinary speed driving, decreasing the speed will turn off the warning light. (For the designated pressure for high speed driving, This warning light may turn on due to natural causes such as natural air leaks or tire inflation pressure changes caused by temperature. In this case, adjusting the tire inflation pressure will turn off the warning light.
SYSTEM OUTLINE
The air pressure sensor installed in the tire wheel detects the tire air pressure and transmits signals to the vehicle side receiver. When the detected tire air pressure is below a specified level, the warning light in the combination meter comes on to inform the driver.
Warnings when the tire pressure is low
- When the tire air pressure is below a specified level, the warning light in the combination meter comes on.
- When the tire air pressure becomes extremely low, the warning light in the combination meter flashes, and a warning buzzer sounds periodically.
DESCRIPTION
1. DESCRIPTION OF SYSTEM
A transmitter equipped with an inflation pressure sensor is installed in a tire wheel assembly. The sensor measures the tire inflation pressure and the measured value is transmitted to an antenna on the body as radio signals and then sent to a receiver from the antenna. When the value is less than the the standard value registered in the receiver, a warning light in the combination meter lights up or blinks with alarming chime.
2. IN CASE WHERE TIRE PRESSURE WARNING LIGHT IS LIT
a. When the warning light does not go out, or when it lights up or blinks with alarming chime during drive, check inflation tire pressure. If the warning light is lit even though the tire inflation pressure is correctly adjusted, the tire could be punctured or the tire pressure monitor valve sub-assembly may be failed.
b. If the warning light is lit during high speed driving, it may go out when the speed is decreased to intermediate or lower speeds (The pressure-increase-indicated-speed or less). (If the vehicle is driven at higher speeds again, the warning light will light up again. Therefore, increase the air pressure to the specified value prior to high speed running.)
c. The actions to be taken when the warning light is lit are different between the vehicle with normal tires and the one with run flat tires.
d. Under the following conditions, the system may not function properly.
- The areas, facilities or devices that use similar radio frequencies are located in vicinity of the vehicle.
- A radio device of similar frequency is used in the vehicle.
- A lot of snow or ice is stuck to the vehicle, especially onto the wheels and around the wheel houses.
- The battery of the sensor has been depleted.
- The tires without tire pressure monitor valve sub-assembly are used.
- Tire chains are used.
- Although the tires with inflation pressure sensors are used, another tire set has been selected by the select switch.
HINT:
- If any other wheels than the specified ones are used, the system may not function properly because the radio waves are differently transmitted from the inflation pressure sensor.
- Depending on the tire type, the tires may not function properly even though the specified wheels are used.
e. When the warning light is lit for the wheel used that has been for 5 years or more, and if the air is leaked from the part where the valve is installed, tightening the tire valve nut may stop the light warning. (Refer to HT.)
3. HANDLING PRECAUTIONS
After removing and installing an ECU or a sensor, output a diagnosis code and check that it is a normal code.
4. IN CASE OF TIRE AND WHEEL REPLACEMENT OR TIRE ROTATION
a. When tires and wheels are replaced, register the transmitter ID without fail.
b. Because no tire pressure monitor valve sub-assembly is attached to the spare tire, the tire pressure warning light remains lit when the spare tire is used due to tire rotation.