Tire Monitoring System: Description and Operation
TIRE AND WHEEL: TIRE PRESSURE WARNING SYSTEM: SYSTEM DIAGRAM
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 a tire wheel assembly. 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 illuminates.
* For differences in the air pressure settings according to different types of tires, a tire pressure warning reset switch has been adopted.
2. WHEN TIRE PRESSURE WARNING LIGHT IS LIT
(a) If the tire pressure warning light does not go off, or when it comes on while driving, check the tire pressure. If the tire pressure warning light comes on within several hours after 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 wells.
* The battery of the sensor has been depleted.
* A wheel without tire pressure warning valve and transmitter is used.
* Tire chains are used.
* If the full-size spare tire is not within the receivable range of the electric wave, a signal may not be received because the full-size spare tire is in a fixed position. Accordingly, the system may not function properly. If there is a possibility that the tire pressure warning system does not receive a signal from the full-size spare tire, rotate the tire 90°.
* 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 sensor.
* Depending on the tire type, the system may not function properly even though the specified wheels are used.
(c) The average usage life of the grommet of the tire pressure warning valve and transmitter is approximately 5 years, at which time it must be replaced.
Re-tighten the valve nut if the valve is leaking air, even if it is less than 5 years old and there is no problem with 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.
3. FUNCTION OF COMPONENTS
4. 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 the local regulations.
* Operate the tire pressure warning reset switch only after the inflation pressures of all tires (including the full-size spare tire) 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 on (IG). After the initialization process has started, 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 the all tires (including the full-size spare tire) have been received.