TIRE PRESSURE WARNING SYSTEM > SYSTEM DESCRIPTION

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1. A tire pressure monitor valve sub-assembly is equipped with a tire pressure sensor and a transmitter and is installed in a tire wheel assembly. The sensor measures the tire pressure and the measured value and transmitter ID are transmitted to the tire pressure monitor receiver assembly on the body as radio waves and then sent to the tire pressure monitor ECU from the tire pressure monitor 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 monitor ECU, the warning light on the combination meter comes on.
   

   1. A direct-sensing type tire pressure warning system has been adopted as standard equipment on all LEXUS GS430/300 models.
      
   2. To address the differences in the air pressure settings by the type of tires, or the differences in pressure between the front and rear tires, a tire pressure warning reset switch has been newly adopted.
      
   3. Along with the adoption of the tire pressure warning reset switch, the warning operation has been changed.
      
   4. TPWS transmitters with different bending angles at the tire pressure monitor valve sub-assembly have been provided for aluminium wheels. (They are not interchangeable with other wheels.)
      
   
   
   
   

1. 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, selection of the tire pressure warning switch "MAIN" / "2nd" may be incorrect.
   

2. Under the following conditions, the system may not function properly.
   

   1. The areas, facilities or devices that use similar radio frequencies are located in the vicinity of the vehicle.
      
   2. A radio device of similar frequency is used in the vehicle.
      
   3. Much of snow or ice is stuck to the vehicle, especially onto the wheels and around the wheel houses.
      
   4. The battery of the sensor has been depleted.
      
   5. The tires without tire pressure monitor valve sub-assembly are used.
      
   6. Snow tires and tire chains are used.
      

   HINT:

   1. 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 tire pressure sensor.
      
   2. Depending on the tire type, the system may not function properly even though the specified wheels are used.
      

3. The average use life of the grommet of the tire pressure monitor valve sub-assembly is approximately 5 years, at which time it must be replaced.
   Re-tighten the valve nut if the valve is air leaking, although it is less than 5 years old and there is no problem with grommets.
   

4. After removing and installing the ECU or a sensor, output a diagnosis code and check that it is a normal code.
   

1. By operating the tire pressure warning reset switch, the tire pressure monitor 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.
   
2. Operate the tire pressure warning reset switch only after the inflation pressures of all 4 tires have been adjusted on the vehicle.
   
3. To initialize the system, press and hold the tire pressure warning reset switch for 3 seconds or longer with the engine switch on (IG). After the system has been initialized, the warning light blinks 3 times (1 second on, 1 second off).
   
4. During initialization, the tire pressure monitor valve sub-assembly measures the inflation pressure of the tires, and registers the signals that are transmitted into the tire pressure monitor ECU at a frequency of one per minute. The initialization process is completed when the signals from the 4 tires have been received.
   
5. The initialization process is canceled if the engine switch is turned off during initialization. To initialize again, the tire pressure warning reset switch must be pressed again. For this reason, once the tire pressure warning reset switch has been pressed, do not turn off the engine switch for a minimum of 20 minutes.
   

1. This switch is installed at the base of the instrument panel on the front passenger seat side.
   
2. 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 log the ID again each time a tire is changed.
   
3. Make sure ID registration is performed by your car dealer.