TIRE PRESSURE WARNING SYSTEM


  1. FUNCTION OF MAIN COMPONENTS

    Component Function
    Tire Pressure Warning Valve and Transmitter

    • Detects the tire pressure, internal temperature and rotational acceleration of the tire, and transmits the measured values and the ID code to the tire pressure warning ECU and receiver.

    • Receives electrical waves for tire position determination from the initiators.*
    Front Tire Pressure Monitor Initiator* Built into the front-left wheelhouse and sends the electrical waves for tire position determination to the sending devices (tire pressure warning valve and transmitter).
    Rear Tire Pressure Monitor Initiator* Built into the rear-left wheelhouse and sends the electrical waves for tire position determination to the sending devices (tire pressure warning valve and transmitter).
    Tire Pressure Monitor Initiator Driver* Operates the tire pressure monitor initiators.
    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.

    • Instructs the initiator driver to determine tire positions.*

    • Confirms the positions of the tires in accordance with information about the intensity of electrical waves for tire position determination from the tire pressure warning valve and transmitter, and sends a signal to display the tire pressure value (based on the measured value) on the multi-information display.*
    Steering Pad Switch Assembly

    • Switches the multi-information display screen according to switch operation.

    • Initializes the system by operating switch operation.
    Main Body ECU (Multiplex Network Body ECU) Receives a signal from the tire pressure warning ECU and receiver and outputs the signal 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* Displays the identified tire pressure and position to inform or warn the driver.
    Speedometer Sends a vehicle speed signal to the tire pressure warning ECU and receiver.

    • *: Models with tire inflation pressure display function

  2. FUNCTION


    1. Tire Inflation Pressure Display Function (Models with Tire Inflation Pressure Display Function)


      1. The multi-information display shows the following to inform the driver of the tire pressure:

        Figure 1. Tire Pressure is Normal

        A01H2F3

        Figure 2. Tire Position Identification has Not Yet been Completed

        A01H2JR

      2. Identification of the tire position is carried out when the power switch is turned on (IG), initialization is performed, or the transmitter ID code is registered. However, under certain conditions, the tire position may not be displayed. In that case, electric wave conditions may be restored by continuously driving to enable the tire position determination.

    2. 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.

        Tech Tips

        The warning pressure (pressure at which the tire pressure warning light illuminates) is not set to a tire pressure that is approximately 75% or less of the specified tire pressure.

        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.

        • The warning pressure (pressure at which the tire pressure warning light illuminates) cannot be set to a tire pressure of approximately 170 kPa or less.*


          • *: Models for Taiwan, Hong Kong and Thailand

        A01H2GOE02

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

      3. The table below shows the warning methods for the tire pressure warning light and multi-information display in the combination meter assembly:

        Detection Condition Tire Pressure Warning Light Multi-information Display*1
        The tire pressure warning system has detected that the tire pressure has become lower than the warning threshold. Illuminates*2 A01H2QU
        The tire pressure warning system has detected a malfunction in the system. Illuminates after blinking for 1 minute*3 A01H2MZ

        • *1: Models with tire inflation pressure display function

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

        • *3: 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.

    3. Initial Check Function


      1. After the power switch is turned on (IG), the tire pressure warning ECU and receiver illuminates the tire pressure warning light for 3 seconds to check the warning light circuits.

    4. 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.

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

        • The tire pressure is adjusted.*


          • *: Models compliant with ECE-R64 legal regulations

      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.*


        • *: Models compliant with FMVSS138 legal regulations

  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 blinks the tire pressure warning light for 1 minute, after which the light stays on. The tire pressure warning ECU and receiver also stores the Diagnostic Trouble Codes (DTCs) in memory.

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