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 the tire pressure warning valve and transmitter and monitors the tire inflation pressure.

    • Outputs the respective signal to the main body ECU (multiplex network body ECU) when a drop in the tire inflation pressure, a system malfunction or the beginning of initialization is detected.
    Main Body ECU (Multiplex Network Body ECU) Receives the signal from the tire pressure warning ECU and receiver and outputs it to the combination meter assembly via CAN communication.
    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 system.

    • Flashes 3 times after initialization.

    • Displays the 2-digit Diagnostic Trouble Code (DTC).
    Multi-information Display 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 by operating the tire pressure warning reset switch on the multi-information display.
    Speedometer Sends a vehicle speed signal to the tire pressure warning ECU and receiver.
    Steering Pad Switch Assembly Initializes the system by operating switch operation.

  2. FUNCTION


    1. Warning Function


      1. When any of the following conditions are met, the tire pressure warning system illuminates the tire pressure warning light to warn the driver.

        Warning Condition (Models Compliant with FMVSS138 Legal Regulations)

        • When the tire pressure decreases to approximately 75% or less of the default tire pressure set during system initialization.
        Warning Condition (Models Compliant with ECE-R64 Legal Regulations)

        • When the tire pressure decreases to approximately 80% or less of the default tire pressure set during system initialization.

        • When the tire pressure decreases rapidly (approximately 20 kPa or more over a period of several minutes) and drops below approximately 80% or less of the tire pressure when warm.

        Tech Tips

        When driving for a certain period of time after the system has been initialized, the system corrects the tire pressure set during initialization according to the vehicle driving conditions and sets the tire pressure when warm.

        A003J7BE04

      2. The tire pressure warning system has 2 warning methods which are used depending on the condition detected.

      3. The table below shows the warning methods for the tire pressure warning light in the combination meter assembly.

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

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

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

    2. Initial Check Function


      1. After the power switch is tuned on (IG), 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 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.

        • 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.

        • The tire pressure is adjusted.

      2. After the initialization operation has completed, the tire pressure warning ECU and receiver receives an initialization signal 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 initialization operation is not used to cancel the warning. The initialization operation is used to turn off the tire pressure warning light.

  3. 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.