Tire Monitoring System: Description and Operation
TIRE AND WHEEL: TIRE PRESSURE WARNING SYSTEM:
SYSTEM DIAGRAM
HINT: The 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 each tire 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 illuminates.
(b) When it is necessary to change the tire pressure setting, use the tire pressure warning reset switch to initialize the system.
2. INITIAL CHECK
(a) After the power switch is turned on (IG), the tire pressure warning light turns on for 3 seconds and then turns off.
HINT: If the tire pressure warning light does not turn on for 3 seconds, troubleshoot the tire pressure warning light circuit.
3. WHEN TIRE PRESSURE WARNING LIGHT IS LIT
(a) If the tire pressure warning light does not go off, or if it turns on while driving, check the tire pressure. If the tire pressure warning light turns on within several hours of adjusting the tire pressure, the tire may have a slow air leak.
(b) Under the following conditions, the system may not function properly:
(1) The system will be disabled in the following conditions:
(When the condition becomes normal, the system will work properly.)
- If tires not equipped with the tire pressure warning valve and transmitters are used.
- If the ID code on the tire pressure warning valve and transmitter is not registered in the tire pressure warning ECU.
- If the tire inflation pressure is absolute pressure: 600 kPa (6 kgf/cm2, 87 psi) or more; relative pressure: 500 kPa (5 kgf/cm2, 72.5 psi) or more.
- If the tire pressure warning valve and transmitter battery voltage drops (battery life: 10 years).
(2) The system may be disabled in the following conditions:
(When the condition becomes normal, the system will work properly.)
- If electronic devices or facilities using similar radio wave frequencies are nearby.
- If a radio set at similar frequencies is in used in the vehicle.
- If a window tint that affects the radio wave signal is installed.
- If there is a lot of snow or ice on the vehicle, in particular around the wheels or wheel housings.
- If non-genuine wheel are used.
- If tire chains are used.
(c) The average usage life of the grommets 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 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 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 power 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 at a frequency of once per minute. The initialization process is completed when signals from all tires have been received. It takes several minutes.