Last Modified: 4-30-2014 6.6 D Doc ID: RM0000018L3001X
Model Year: 2006 Model: LX470 Prod Date Range: [05/2005 -           ]
Title: TIRE AND WHEEL: TIRE PRESSURE WARNING SYSTEM: SYSTEM DESCRIPTION; 2006 MY LX470 [05/2005 -        ]

SYSTEM DESCRIPTION

1. DESCRIPTION OF SYSTEM

(a) A tire pressure monitor valve sub-assembly is equipped with a tire pressure sensor and a transmitter and is installed in each tire wheel assembly. The sensor measures the tire pressure. Then the measured value and transmitter ID are transmitted to the tire pressure antenna in the door mirror as radio waves, which are sent to the tire pressure monitor ECU. 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.

  • This system has a tire pressure warning reset switch to address the differences in the air pressure settings by the type of tires, and the differences in pressure between the front and rear tires.
  • This system has transmitters with different bending angles at the tire pressure monitor valve sub-assembly. These transmitters are not interchangeable with other wheels.

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 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. If the tire pressure warning light comes on even after adjusting the tire pressure, there is a strong possibility that the ECU and meter are not connected properly.

(b) Under the following conditions, the system may not function properly.

  • Similar radio frequencies are located in the 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.
  • Tires without a tire pressure monitor valve sub-assembly are used.
  • Snow tires and tire chains are used.

HINT:

  • If wheels other than specified are used, the system may not function properly because the radio waves are differently transmitted from the tire pressure sensor.
  • Depending on the type of tire, the system may not function properly even though the specified wheels are used.

(c) The average 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 leaking air, if it is less than 5 years old, and there is no problem with the grommets.

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

3. FUNCTION OF COMPONENTS

Components

Function

Tire pressure monitor valve sub-assembly
  • Combined as a single unit with a disc wheel air valve, it measures tire pressure and temperature and transmits an ID number for measurement value and identification.
  • The battery is built into the valve.

Tire pressure antenna
  • Receives a necessary signal from the transmitter and transmits to the tire pressure monitor ECU.

Tire pressure monitor ECU
  • Receives the signal from the receiver and identifies it as vehicle's own signal.
  • If the measurement value is equal to or lower than the specified value, it transmits a signal so that the air pressure warning light on the combination meter comes on.

Tire pressure warning light
  • Located in the combination meter, it informs the driver of lowered tire air pressure and system failure.

Tire pressure warning reset switch
  • Enters the initialization mode for tire or wheel replacement, or tire rotation.

Tire pressure warning select switch
  • When 2 sets of ID are registered in the tire pressure monitor ECU, either of the sets can be selected by changing the switch between "MAIN" and "2nd".

4. TIRE PRESSURE WARNING RESET SWITCH

  • 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.
  • 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 ON. After the system has been initialized, the warning light blinks 3 times (1 second on, 1 second off).
  • 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 all the tires have been received.

5. TIRE PRESSURE WARNING SELECT SWITCH

  • The tire pressure warning select switch is inside the glove box.
  • Tire pressure monitor ECU can be used to register 2 sets of transmitter IDs, and can select one or the other using the tire pressure warning select switch. Consequently, there is no need to log the ID again each time a tire is changed.
  • Make sure ID registration is performed by your car dealer.