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Tire Monitoring System: Description and Operation








TIRE AND WHEEL: TIRE PRESSURE WARNING SYSTEM: SYSTEM DESCRIPTION

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 IDs are transmitted to the tire pressure warning antenna on the body as radio waves and then sent to the tire pressure warning ECU and receiver from the tire pressure warning antenna. 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 and receiver, the tire pressure warning light on the combination meter comes on and "LOW TIRE" will appear on the multi-information display.
- For 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.
- Tire pressure warning system transmitters with different bending angles at the tire pressure warning valve and transmitter have been provided for aluminium wheels. (They are not interchangeable with other wheels.)





2. INITIAL CHECK





(a) After the engine switch is turned on (IG), the tire pressure warning light comes on for 3 seconds and then goes off.
HINT:
If the tire pressure warning light does not come 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 the tire pressure. If the tire pressure warning light comes on within several hours of 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.
(b) Under the following conditions, the system may not function properly:
- Areas, facilities or devices that use similar radio frequencies are located in the vicinity of the vehicle.
- Devices using similar radio frequencies are used in the vehicle.
- Large amounts snow or ice are stuck to the vehicle, especially on the wheels and around the wheel houses.
- The battery of the transmitter is depleted.
- The Tires and wheels without the tire pressure warning valve and transmitters are used.
- Snow tires and tire chains are used.
- The registered set of the tires and wheels does not correspond to the selection of the tire pressure warning select switch.
- If wheels other than the specified ones are used, the system may not function properly because different radio waves are transmitted from the tire pressure warning valve and transmitter.
- A type of film that affects radio waves is attached to the windows.
- Depending on the tire type, the tire pressure warning valve and transmitter may not function properly even if the specified wheels are used.
- The system may not function properly unless it is initialized with the tire pressures at the specified values.
- 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 useful 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 sensor, check for DTCs and verify that it is a normal system code.
4. FUNCTION OF COMPONENTS






5. TIRE PRESSURE WARNING RESET SWITCH (SATELLITE SWITCH)

- By operating the tire pressure warning reset switch, the tire pressure warning ECU and receiver 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 4 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 engine switch on (IG). When the system receives the initialization signal, 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 and receiver at a frequency of once per minute. The initialization process is completed when signals from the 4 tires have been received.
- Initialization is usually completed in 2 or 3 minutes.

6. TIRE PRESSURE WARNING SELECT SWITCH (SATELLITE SWITCH)

- This switch is installed at the base of the instrument panel on the driver seat side.
- The 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 register the ID again each time a tire is changed.
- Make sure ID registration is performed by your car dealer.

SYSTEM DIAGRAM




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