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Tire Monitoring System: Description and Operation









TIRE AND WHEEL: TIRE PRESSURE WARNING SYSTEM:

SYSTEM DIAGRAM




HINT: Each tire pressure warning valve and transmitter sends information on the temperature inside the tire, the ID, and the tire pressure.

SYSTEM DESCRIPTION

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 and 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.
(b) For the differences in the air pressure settings by the type of tires, a tire pressure warning reset switch has been adopted.
(c) The tire pressure warning ECU can be used to register 2 sets of transmitter IDs, and either set can be selected using the tire pressure warning select switch. Consequently, there is no need to register the ID each time of wheels are changed.





2. INITIAL CHECK





(a) The tire pressure warning light comes on for 3 seconds after turning the engine switch on (IG) and then goes off.
HINT: If the tire pressure warning light does not comes on for 3 seconds, troubleshoot the tire pressure warning light circuit.





3. 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.
(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.
- The tires without tire pressure warning valve and transmitters are used.
- Tire chains are used.
- When the ground spare tire is not within the receivable range of the electric wave, a signal may not be received because the ground spare tire is fixed. 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 ground spare tire, rotate the tire 90 to 270 degrees.
- 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 warning valve and transmitters.
- A type of film that affects radio waves is attached to the windows.
- Depending on the tire type, the system may not function properly even though the specified wheels are used.
- The tire pressure is abnormally high (absolute pressure: 600 kPa (6 kgf/cm2, 87 psi) or more; relative pressure: 500 kPa (5 kgf/cm2, 72.5 psi) or more).

(c) The average usage life of the grommet of the tire pressure warning valve and transmitter is approximately 10 years, at which time it must be replaced.
If a tire pressure warning valve and transmitter is removed from a wheel, replace the grommet with a new one.
(d) After removing and installing the ECU or a tire pressure warning valve and transmitter, check for a diagnostic trouble code and verify that it is a normal code.
4. FUNCTION OF COMPONENTS






5. 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 ground 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 engine switch on (IG). When the system receives the initialization signal, the tire pressure warning light blinks 3 times (1 second on, 1 second off).
- During initialization, the tire pressure warning valve and transmitters measure the inflation pressure of the tires, and register 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 wheels (including the ground spare tire) have been received.

6. TIRE PRESSURE WARNING SELECT SWITCH
(a) This switch is installed at the base of the instrument panel on the front passenger seat side.
(b) The ECU can be used to register 2 sets of the tire pressure warning select switch. Consequently, there is no need to register the ID each time of wheels are changed.
(c) Make sure ID registration is performed by your car dealer.
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