Tire Monitoring System: Description and Operation
SYSTEM DIAGRAM
SYSTEM DESCRIPTION
1. DESCRIPTION OF SYSTEM
(a) A 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 comes on.
^ For the differences in the air pressure settings by the type of tires, a tire pressure warning reset switch has been adopted.
2. WHEN TIRE PRESSURE WARNING LIGHT IS LIT
(a) When the tire pressure warning light does not go off, or when it comes on during driving, check 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. If the tire pressure warning light comes on even after adjusting the tire pressure, the setting of the tire pressure warning select switch "MAIN"/"2nd" may be incorrect.
(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.
^ The tires without tire pressure warning valve and transmitter are used.
^ Snow tires or 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 sensor.
^ Depending on the tire type, the system may not function properly even though the specified wheels are used.
(c) The average usable 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, although 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 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 5 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 on. After the system has been initialized, 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 5 tires have been received.
5. TIRE PRESSURE WARNING SELECT SWITCH
^ This switch is installed at the base of the instrument panel on the front passenger seat side.
^ The control ECU can be used to register two sets of transmitter IDs, and can select one or the other using the tire select switch. Consequently, there is no need to register the ID again each time a tire is changed.
^ Make sure ID registration is performed by your car dealer.