TIRE PRESSURE WARNING SYSTEM SYSTEM DESCRIPTION


  1. DESCRIPTION OF SYSTEM


    1. The tire pressure warning system warns the driver when the tire pressure has decreased in order to decrease CO2 emissions and enhance safety.

    2. The tire pressure warning system illuminates the tire pressure warning light to warn the driver when any of the following conditions is met:


      • Due to the operation of the tire pressure warning reset switch, the tire pressure drops to approximately 75% or less of the tire pressure set during system initialization.

      • The tire pressure drastically decreases (approximately 20 kPa (0.2 kgf/cm2, 2.9 psi) or more within several minutes) to approximately 75% or less of the tire pressure* when the tires are warmed.

        *: If initialization is performed and the vehicle is driven for a certain period of time, the tire pressure set during system initialization is adjusted and set to the tire pressure when the tires are warmed from the driving conditions.

      Tech Tips

      The tire pressure warning pressure (pressure at which the tire pressure warning light is illuminated) cannot be set to a value equal to, or less than, the lower limit threshold value*.

      GTS Data List Item


      • *: "Threshold of Low-pressure (Lower Limit)"

      The value that is approximately 75% of the set tire pressure during initialization*1 and the lower limit threshold value*2 are both displayed on the GTS, and the higher of the two values is set as the tire pressure warning threshold value.


      • *1: "Initial Threshold of Low-pressure"

      • *2: "Threshold of Low-pressure (Lower Limit)"

      Note

      If the tire pressure is decreased approximately 20 kPa (0.2 kgf/cm2, 2.9 psi) or more in order to adjust the tire pressure, even if the adjusted tire pressure is 75% or more than the tire pressure set during system initialization, the tire pressure warning light may illuminate if the tire pressure drops below 75% of the tire pressure set when the tires are warmed. In this case, perform initialization again.

      B007OXXE04
      Text in Illustration
      *1 Tire Pressure *2 Tire Pressure When Tires are Warmed
      *3 Tire Pressure During Initialization *4 75% of Tire Pressure When Tires are Warmed
      *5 75% of Tire Pressure During Initialization or Lower Limit Threshold Value *6 Tire Pressure Warning Light Illuminates
      *7 Tire Pressure (Normal) *8 Tire Pressure (Drastically Decreasing)
      *9 Elapsed Time - -

    3. The tire pressure warning ECU and receiver receives the transmitter ID, temperature and tire pressure information from the tire pressure warning valve and transmitters shown in the following illustration. This information is used to determine when the pressure in one of the tires has dropped.

      B007R5XE02
    Text in Illustration
    *1 Tire Pressure Warning ECU and Receiver *2 Tire Pressure Warning Valve and Transmitter
    *3

    Combination Meter Assembly

    - Tire Pressure Warning Light

    		 *4 Tire Pressure Warning Reset Switch
    *a Front - -

  2. DESCRIPTION OF REGISTRATION


    1. When tires and wheels are replaced, always ensure that each transmitter ID is correctly registered.

    2. When one or more tire pressure warning valve and transmitters or the tire pressure warning ECU and receiver is replaced, the transmitter IDs for all of the tire pressure warning valve and transmitters must be re-registered. Before registering the transmitter ID of the new tire pressure warning valve and transmitter, check the Data List and record all of the transmitter IDs that are already registered.

  3. TIRE PRESSURE WARNING RESET SWITCH


    1. By operating the tire pressure warning reset switch, the tire pressure warning ECU and receiver can be set to issue a warning at an inflation pressure that corresponds to the type of tires fitted to the vehicle. Therefore, the warning threshold must be set to the proper value in order to comply with local regulations.

    2. Operate the tire pressure warning reset switch only after the inflation pressures of all tires have been adjusted on the vehicle.

  4. DESCRIPTION OF INITIALIZATION


    1. During initialization, the tire pressure warning valve and transmitters measure the inflation pressure of the tires, and register the signals that are transmitted into the tire pressure warning ECU and receiver at a frequency of about once per minute. The initialization process is completed when signals from all tires have been received.

    2. Perform initialization in the following cases:


      1. Before delivery of a new vehicle.

      2. After replacement of the tire pressure warning ECU and receiver*.

      3. After replacement of a tire pressure warning valve and transmitter*.

      4. When the specified tire pressure changes due to the use of a different size or type of tire.

      5. When the specified tire pressure changes due to a change in the vehicle load, the speed range that the vehicle will be used in, etc.

      6. When a tire rotation is performed and the specified tire pressures are different for the front and rear of the vehicle.

        Tech Tips

        *: Perform initialization after the transmitter ID registration is completed.

  5. DESCRIPTION OF ID SWITCHING FUNCTION


    1. By designating the ID registration location, it is possible to register transmitter IDs for both the main and 2nd sets of tires.

    2. When IDs are registered for both the main transmitter side and sub-transmitter (2nd) side, it is possible to switch between the main transmitter side and sub-transmitter (2nd) side by operating the tire pressure warning reset switch Click here.

      Note

      Be careful as the method to perform ID switching differs from the method to perform initialization.

    3. When reading the status for a registered ID, it is only possible to read the ID information for the selected set of tires.

      Tech Tips

      In order to read the IDs registered for the main tire set, it is necessary to set the ID selection setting to "Main". Likewise, it is necessary to set the ID selection setting to "2nd" in order to read IDs registered for the 2nd set of tires.

  6. 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 pressure.

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

    • When the tire pressure warning ECU and receiver detects that the vehicle speed signal is lost, it determines that the vehicle is being driven.
    Tire Pressure Warning Valve and Transmitter Detects the pressure and internal temperature of the tire and transmits the measured values and the ID code to the tire pressure warning ECU and receiver.
    Tire Pressure Warning Reset Switch

    • Stores the warning threshold determined by the current tire pressure as the set pressure in the tire pressure warning ECU and receiver when operated.

    • By operating this switch, ID switching can be performed.
    Combination Meter Assembly Transmits the vehicle speed signal to the tire pressure warning ECU and receiver.
    Tire Pressure Warning Light

    • Illuminates after blinking for 1 minute to warn the driver in accordance with the signal from the tire pressure warning ECU and receiver.

    • Displays 2-digit Diagnostic Trouble Codes (DTC).