Tire Monitoring System: Description and Operation

TIRE AND WHEEL: TIRE PRESSURE WARNING SYSTEM

SYSTEM DESCRIPTION

1. DESCRIPTION OF SYSTEM
(a) Each tire pressure warning valve and transmitter is equipped with a tire pressure sensor and a transmitter and is installed in each tire wheel. The sensor measures the tire pressure. The measured value and transmitter ID are transmitted to the tire pressure warning antenna and receiver on the body as radio waves and then sent to the tire pressure warning ECU from the tire pressure warning antenna and receiver. If the transmitter ID has already been registered, the ECU compares the measured air pressure value with the standard value. When the value is less than the standard value registered in the tire pressure warning ECU, the warning light on the combination meter turns on.
The tire pressure warning reset switch addresses the differences in the air pressure settings by the type of tires.





2. INITIAL CHECK






(a) After the ignition switch is turned to ON, the tire pressure warning light turns on for 3 seconds and then turns off.
HINT: If the warning light does not turn on for 3 seconds, troubleshoot the pressure warning light circuit.





3. WHEN TIRE PRESSURE WARNING LIGHT IS LIT
(a) When the tire pressure warning light does not go off, or when it turns on during driving, check the tire pressure. If the tire pressure warning light turns on within several hours of adjusting the tire pressure, the tire may have a slow air leak.
(b) Under the following conditions, the system may not function properly.
- Facilities or devices that use similar radio frequencies are located in the vicinity of the vehicle.
- A radio device of similar frequency is used in the vehicle.
- A large amount 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.
- Tires without a tire pressure warning valve and transmitter are used.
- Tire chains are used.
- If any wheels other than the specified ones are used, the system may not function properly because interference may prevent the radio waves from being correctly transmitted from the tire pressure warning valve and transmitter.
- A type of film that affects radio waves is attached to the windows.
- Depending on the tire type, the system may not function properly even if the specified wheels are used.
- The tire pressure is abnormally high (absolute pressure: 600 kPa (6 kgf/cm2, 87 psi) or more; relative pressure: 500 kPa (5 kgf/cm2, 72.5 psi) or more).

(c) The average usage life of the grommet of the tire pressure warning valve and transmitter is approximately 10 years, at which time it must be replaced.
If a tire pressure warning valve and transmitter is removed from a wheel, replace the grommets.
(d) After removing and installing the ECU or a sensor, check for a diagnostic trouble code and verify that it is a normal code.
4. FUNCTION OF COMPONENTS






5. TIRE PRESSURE WARNING RESET SWITCH

- By operating the tire pressure warning reset switch, the tire pressure warning ECU can be set to issue a warning at an inflation pressure that corresponds to the type of tires. Therefore, the dealer must set the warning threshold to the proper value in order to comply with local regulations.
- Operate the tire pressure warning reset switch only after the inflation pressures of all tires have been adjusted on the vehicle.
- To initialize the system, press and hold the tire pressure warning reset switch for 3 seconds or longer with the ignition switch in the ON position. When the system receives the initialization signal, the warning light blinks 3 times (1 second on, 1 second off).
- During initialization, the tire pressure warning valve and transmitter measures the inflation pressure of the tires, and registers the signals that are transmitted into the tire pressure warning ECU at a frequency of once per minute. The initialization process is completed when signals from all tires have been received.


SYSTEM DIAGRAM





HINT: The tire pressure warning valve and transmitter sends information on the temperature inside the tire, the ID, and the tire pressure.