TIRE PRESSURE WARNING SYSTEM


  1. FUNCTION OF MAIN COMPONENTS

    Component Function
    Tire Pressure Warning Valve and Transmitter Detects the tire inflation pressure and temperature of the tire and transmits the measured value and ID code to the tire pressure warning ECU and receiver.
    Tire Pressure Warning ECU and Receiver

    • Receives the data from each tire pressure warning valve and transmitter and monitors its tire inflation pressure.

    • When the tire pressure warning ECU and receiver detects a drop in tire inflation pressure, a system malfunction or the beginning of initialization, it outputs the respective signal to the combination meter assembly.

    • When the tire pressure warning ECU detects a problem with the vehicle speed signal, it uses changes in the signal strength from the tire pressure warning valve and transmitter as a judgment standard. If the ECU detects any changes in the signal strength from the tire pressure warning valve and transmitter, it determines that the vehicle is being driven.
    Tire Pressure Warning Reset Switch The current tire inflation pressures are stored in the tire pressure warning ECU and receiver as set pressures when the tire pressure warning reset switch is operated.
    Combination Meter Assembly Transmits the vehicle speed signal to the tire pressure warning ECU and receiver.
    Tire Pressure Warning Light Warns the driver by illuminating or blinking for one minute in accordance with the signal from the tire pressure warning ECU and receiver.
    Main Body ECU (Multiplex Network Body ECU)

    • Provided with a gateway function, the main body ECU (multiplex network body ECU) is used to transmit data between the tire pressure warning ECU and receiver and combination meter assembly.

    • The main body ECU (multiplex network body ECU) is connected to the combination meter assembly via CAN V bus.

  2. FUNCTION


    1. Warning Function


      1. The tire pressure warning ECU and receiver has 2 warning methods, depending on the condition detected.

      2. The table below shows the warning methods for the warning light in the combination meter assembly.

        Detection Condition Tire Pressure Warning Light
        The tire pressure warning ECU and receiver has detected that a tire inflation pressure becomes lower than the threshold. Illuminates*1
        The tire pressure warning ECU and receiver has detected a malfunction in the system. Illuminates after blinking for 1 minute*2

        Tech Tips

        *1: If the tire pressure warning light illuminates, adjust the tire inflation pressure.

        *2: If the tire pressure warning light illuminates after blinking for 1 minute, the system is malfunctioning and must be repaired to turn off the light. For details, refer to the Repair Manual.

    2. Initial Check Function


      1. After the ignition switch is turned to ON, the tire pressure warning ECU and receiver illuminates the tire pressure warning light for 3 seconds to check the warning light circuit.

    3. Initialization Function


      1. The warning threshold is calculated from the tire inflation pressure value at the time of initialization and memorized in the tire pressure warning ECU and receiver. Therefore, the tire pressure warning ECU and receiver should be initialized after:


        • The recommended tire inflation pressure changes due to changes in vehicle weight, speed conditions or tire size.

        • Replacement of the tire pressure warning ECU and receiver or a tire pressure warning valve and transmitter.

        • The tires are rotated on a vehicle with different recommended tire inflation pressures for the front and rear tires.

      2. Initialization starts after the tire pressure warning reset switch is pressed and the tire pressure warning light illuminates slowly 3 times.

      3. Before performing initialization, adjust the tire inflation pressure to the recommended pressure when the tires are cold. For details, refer to the Repair Manual.

      4. The tire pressure warning reset switch is not used to cancel the warning. Do not press the tire pressure warning reset switch to turn off the tire pressure warning light.

  3. CONSTRUCTION


    1. Tire Pressure Warning Valve and Transmitter


      1. The tire pressure warning valve and transmitters are integrated in the tire valves. Each transmitter consist of a lithium battery, sensor and transmitter.

      2. Make sure not to damage the urethane covered backside of the transmitter (the surface opposite to the side with the ID code) with anything sharp.

      3. The transmitter directly measures tire inflation pressure and temperature to see if the vehicle can continue to run.

      4. The transmitter transmits the measured tire inflation pressure and temperature values and the determination result whether or not the vehicle can continue running to the tire inflation pressure warning ECU and receiver on a frequency of 433.90 MHz.

      5. Depending on the timing of the data transmission, it may take several minutes to receive the data from the tire pressure warning valve and transmitter.

      6. The ID code is written on the tire pressure warning valve and transmitter.

        A01UX2IE05
        Text in Illustration
        *1 Tire Pressure Warning Valve and Transmitter *2 Grommet
        *3 Washer *4 Nut
        *5 Tire Valve Core *6 Cap
        *7 Lithium Battery *8 Sensor and Transmitter
        *9 ID Code (Hexadecimal 7 Digits) - -

        Tech Tips


        • The lithium batteries of the tire pressure warning valve and transmitters are non-replaceable. If a battery is depleted, the tire pressure warning valve and transmitter must be replaced (Battery life: approximately 10 years).

        • A new tire pressure warning valve and transmitter is shipped in sleep mode to prevent the battery from depleting in storage. When the tire inflation pressure in the detection portion of the tire pressure warning valve and transmitter increases or decreases by 40 kPa (0.4 kgf/cm2, 5.8 psi) within 30 seconds, the tire pressure warning valve and transmitter automatically cancels sleep mode. Once sleep mode is canceled, the tire pressure warning valve and transmitter cannot return to sleep mode.

        • When replacing a tire pressure warning valve and transmitter, each of the tire pressure warning valve and transmitter ID codes must be registered. If even one of the transmitters is replaced, the ID codes of all tire pressure warning valves and transmitters must be registered again. Record all the existing ID codes before beginning the process to enter new ID codes.

        • To register an ID code, use the Global TechStream (GTS) to enter the ID code that is indicated on the tire pressure warning valve and transmitter.

        • Be careful not to damage the tire pressure warning valve and transmitters when removing and reinstalling them.

        • Replace the grommet, valve core, washer and nut with new ones when tire pressure warning valve and transmitter is being replaced or being removed and reinstalled. This is necessary to ensure sealing performance.

        • When replacing a valve cap, use only the specified cap. If an unspecified cap is used, it may seize to the tire pressure warning valve and transmitter.

        • For details, refer to the Repair Manual.

  4. DIAGNOSIS


    1. To inform the driver when the tire pressure warning ECU and receiver detects a malfunction in the system, the tire pressure warning ECU and receiver will blink the tire pressure warning light for 1 minute, after which the light will illuminate. The tire pressure warning ECU and receiver will also store Diagnostic Trouble Codes (DTCs) in memory.

    2. 5-digit DTCs can be read by connecting the Global TechStream (GTS) to the DLC3. For details, refer to the Repair Manual.