System Diagram

System Diagram:

SYSTEM DIAGRAM

DESCRIPTION

1. DESCRIPTION OF SYSTEM
a. A tire pressure monitor valve sub-assy equipped with tire pressure sensor, transmitter and is installed in a tire wheel assy. The sensor measures the tire pressure and the measured value and transmitter ID are transmitted to the tire pressure monitor receiver assy 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 and the standard value. When the value is less than the standard value registered in the tire pressure monitor ECU, the warning lamp on the combination meter comes on.

2. WHEN TIRE PRESSURE WARNING LAMP IS LIT
a. When the warning lamp does not go off, or when it comes on during driving, check tire pressure. If the warning lamp is lit even though the tire pressure is correctly adjusted, the tire could be punctured.
b. Under the following conditions, the system may not function properly.
- The areas, 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 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.
- The tires without tire pressure monitor valve sub-assy are used.
- Tire chains are used.
- Wheels other than manufacturer spec 4RUNNER wheels are used.

HINT:
- 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.
- Depending on the tire type, the system may not function properly even though the specified wheels are used.

c. The average use life of the grommet of the tire pressure monitor valve sub-assy is approximately 5 years, at which time it must be replaced.
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