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.
TIRE AND WHEEL: TIRE PRESSURE WARNING SYSTEM: 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 and wheel. 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 turns on. The tire pressure warning reset switch addresses the differences in the air pressure settings by the type of tires.
2. INITIAL CHECK
(a) After the ignition switch is turned on (IG), the tire pressure warning light turns on for 3 seconds and then turns off.
HINT
If the warning light does not turn on for 3 seconds, troubleshoot the tire pressure warning light circuit 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 after adjusting the tire pressure, the tire may have a slow air leak.
(b) The system will be disabled in the following conditions: (When the condition becomes normal, the system will work properly.)
The tires without tire pressure warning valve and transmitters are used.
The ID of a tire pressure warning valve and transmitter has not been registered in the ECU.
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).
The battery of the sensor has been depleted.
(c) The system may be disabled in the following conditions: (When the condition becomes normal, the system will work 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 film or window tint that may interfere with radio waves is attached on the glass.
A large amount of snow or ice is stuck to the vehicle, especially onto the wheels and around the wheel wells.
Use of non-genuine wheels may result in the system failure or air-leak.
Tire chains are used.
If the spare tire is in a location subject to poor radio wave reception.
If a large metallic object which can interfere with signal reception is put in the trunk.
(d) When the full-size spare tire is not within the receivable range of the electric wave, a signal may not be received because the full-size 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 full-size spare tire, rotate the tire 90 to 270°.
(e) After removing and installing the ECU or a sensor, check for a diagnostic trouble code and verify that it is a normal system 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 standard pressure 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 (IG). After the initialization process has started, 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 tire, and registers the signals that are transmitted into the tire pressure warning ECU at a frequency of once per 3 minutes. The initialization process is completed when signals from all the tires have been received. It takes a few minutes.