TIRE PRESSURE WARNING SYSTEM


  1. FUNCTION OF MAIN COMPONENTS

    Component Function
    Tire Pressure Warning ECU and Receiver

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

    • Outputs the respective signal to the combination meter assembly when a drop in the tire inflation pressure, a system malfunction or the beginning of initialization is detected.

    • When the tire pressure warning ECU and receiver 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 Valve and Transmitter Measures the inflation pressure and internal temperature of the tire and transmits the measured value and the ID code to the tire pressure warning ECU and receiver.
    Tire Pressure Warning Reset Switch The appropriate inflation pressure of the tires currently mounted on the vehicle are stored in the tire pressure warning ECU and receiver by operating the tire pressure warning reset switch.
    Combination Meter Assembly Transmits the vehicle speed signal to the tire pressure warning ECU and receiver.
    Combination Meter Assembly Tire Pressure Warning Light Illuminates or stays on after blinking for 1 minute to warn the driver in accordance with the signal from the tire pressure warning ECU and receiver.

  2. FUNCTION


    1. Warning Function


      1. The tire pressure warning ECU has 3 warning methods that are used, depending on the condition detected.

        Tire Pressure Warning Light Detection Condition
        Illuminates*1 The tire pressure warning ECU and receiver has detected that the inflation pressure of a tire has become lower than the threshold.
        Stays on after blinking for 1 minute*2 The tire pressure warning ECU and receiver has detected a malfunction in the system.
        Blinks 3 times When the tire pressure warning reset switch is pressed.

        Tech Tips

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

        *2: If the tire pressure warning light stays on after blinking for 1 minute, the system is malfunctioning and must be repaired to turn off the light.

    2. Initial Check Function


      1. After turning the power switch on (IG), the tire pressure warning ECU illuminates the tire pressure warning light for 3 seconds to check the warning light circuit.

    3. Initialization Mode Function


      1. The warning threshold is calculated from the tire inflation pressure 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.

        • The tire pressure warning ECU and receiver or the tire pressure warning valve and transmitter are replaced.

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

      2. Adjust the tire inflation pressure to the specified cold tire inflation pressure before performing initialization. For the initialization procedure, refer to the Repair Manual.

  3. CONSTRUCTION


    1. Tire Pressure Warning Valve and Transmitter


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

      2. The tire pressure warning valve and transmitter directly measures tire inflation pressure and temperature.

      3. The transmitter transmits the measured tire inflation pressure and temperature values to the tire pressure warning ECU and receiver on a frequency of 315 MHz*1 or 433 MHz*2.

        *1: Models compliant with FMVSS138 legal regulations

        *2: Models compliant with ECE-R64 legal regulations

      4. The reception of a signal from a tire pressure warning valve and transmitter may be delayed by a few minutes due to the timing of data transmission.

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

        A004V4OE02
        Text in Illustration
        *1 Tire Pressure Warning Valve and Transmitter *2 Washer
        *3 Nut *4 Tire Valve Core
        *5 Cap *6 Lithium Battery
        *7 Sensor and Transmitter *8 ID Code (Hexadecimal 7 Digits)

        Tech Tips


        • The lithium batteries of the tire pressure warning valve and transmitter are of a non-replaceable type. If the lithium battery is depleted, the tire pressure warning valve and transmitter must be replaced.

        • A new tire pressure warning valve and transmitter is shipped in sleep mode to prevent the battery from depleting in storage. When the 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.

        • After a tire pressure warning valve and transmitter is replaced, the ID code of the tire pressure warning valve and transmitter must be registered in the tire pressure warning ECU. 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.

        • When replacing a tire pressure warning valve and transmitter, the ID codes of each tire pressure warning valve and transmitter must be registered. Even if only 1 tire pressure warning valve and transmitter is replaced, the ID codes of all the tire pressure warning valve and transmitters must be registered again. Record all existing ID codes before beginning the process to enter new ID codes.

        • Replace the grommet when the tire pressure warning valve and transmitter are being replaced to ensure the sealing performance. Note that the grommet is not reusable.

        • When replacing tire valve caps, do not use tire valve caps other than those specified. The cap may become stuck.

        • Be careful not to damage the tire pressure warning valve and transmitter during tire removal or installation.

        • 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 stay on. It 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.