METER / GAUGE SYSTEM Speed Signal Circuit

DESCRIPTION

The combination meter assembly receives the vehicle speed signal from this circuit. The wheel speed sensors produce an output that varies according to the vehicle speed. The wheel speed sensor output is received by the skid control ECU (brake actuator assembly) which uses this information to create the vehicle speed signal*. The vehicle speed signal consists of pulses sent to the combination meter assembly from the skid control ECU (brake actuator assembly). To create this signal, 12 V is output from IG2 which is behind a resistor in the combination meter assembly. This voltage is sent to the skid control ECU (brake actuator assembly). The pulse signal is created by switching the transistor in the skid control ECU (brake actuator assembly) on and off, making the voltage on the wire drop to 0 V. A similar system is used for the output of this signal from the combination meter assembly via terminal +S. A voltage of 12 V is applied to terminal +S from each ECU or relay that is connected to this terminal. The transistor in the combination meter assembly is controlled by the signal from the skid control ECU (brake actuator assembly). When this transistor is turned on, this transistor makes the voltage supplied by the various ECUs (via their respective internal resistors) drop to 0 V. Each ECU connected to terminal +S of the combination meter assembly controls its respective system based on this pulse signal.


Tech Tips

This circuit is used for the systems connected to terminal +S. This signal is not used for combination meter assembly operation. Combination meter assembly components such as the speedometer operate using data received via CAN communication.

WIRING DIAGRAM

B006YYRE01

CAUTION / NOTICE / HINT

Note


  • When replacing the combination meter assembly, always replace it with a new one. If a combination meter assembly which was installed to another vehicle is used, the information stored in it will not match the information from the vehicle and a DTC may be stored.

  • Before replacing the ECM, certification ECU (smart key ECU assembly)*, refer to Service Bulletin.


    • *: w/ Smart Entry and Start System

PROCEDURE


  1. INSPECT ECU TERMINAL VOLTAGE (INPUT VOLTAGE)

    B006XXEC51
    *a

    Front view of wire harness connector

    (to Combination Meter Assembly)

    1. Disconnect the K21 combination meter assembly connector.

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      K21-6 (+S) - Body ground Ignition switch ON 11 to 14 V

      Tech Tips

      If any of the ECUs specified in the wiring diagram supplies power to the combination meter assembly, the combination meter assembly will output a waveform.

      Result
      Proceed to
      OK
      NG

    NG

    CHECK HARNESS AND CONNECTOR (EACH ECU - COMBINATION METER ASSEMBLY) Click here

    OK

  2. INSPECT COMBINATION METER ASSEMBLY (OUTPUT VOLTAGE)

    B006X5IC01
    *a

    Front view of wire harness connector

    (to Skid Control ECU (Brake Actuator Assembly))

    1. Connect the K21 combination meter assembly connector.

    2. Disconnect the A34 skid control ECU (brake actuator assembly) connector.

    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      A34-34 (SP1) - Body ground Ignition switch ON 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) - COMBINATION METER ASSEMBLY) Click here

    OK

  3. INSPECT SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) (INPUT WAVEFORM)

    B006XIQC43
    *a

    Component with harness connected

    (Combination Meter Assembly)

    1. Check the input waveform.


      1. Connect the A34 skid control ECU (brake actuator assembly) connector.

      2. Remove the combination meter assembly with the connector(s) still connected.

      3. Connect an oscilloscope to terminal K21-5 (SI) and body ground.

      4. Turn the ignition switch to ON.

      5. Turn a wheel slowly.

      6. Check the signal waveform according to the condition(s) in the table below.

        Item Condition
        Tester connection K21-5 (SI) - Body ground
        Tool setting 5 V/DIV., 20 ms./DIV.
        Condition Ignition switch ON, wheel being rotated
        OK
        The waveform is similar to that shown in the illustration.

        Tech Tips

        When the system is functioning normally, one wheel revolution generates 4 pulses. As the vehicle speed increases, the width indicated by (A) in the illustration narrows.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

    NG

    REPLACE SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) for RHD: Click here
    REPLACE SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) for LHD: Click here

  4. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE ACTUATOR ASSEMBLY) - COMBINATION METER ASSEMBLY)


    1. Disconnect the K21 combination meter assembly connector.

    2. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      A34-34 (SP1) - K21-5 (SI) Always Below 1 Ω
      A34-34 (SP1) or K21-5 (SI) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  5. CHECK HARNESS AND CONNECTOR (EACH ECU - COMBINATION METER ASSEMBLY)


    1. Disconnect the A24*1 ECM connector.

    2. Disconnect the A23*2 ECM connector.

    3. Disconnect the A22*3 ECM connector.

    4. Disconnect the K3 radio and display receiver assembly*4 connector.

    5. Disconnect the K62 certification ECU (smart key ECU assembly)*5 connector.

    6. Disconnect the K17 navigation ECU*6 connector.

    7. Disconnect the K10 stereo component amplifier assembly*7 connector.

    8. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      K21-6 (+S) - Body ground Always 10 kΩ or higher

    9. Connect the A24*1 ECM connector.

    10. Connect the A23*2 ECM connector.

    11. Connect the A22*3 ECM connector.

    12. Connect the K3 radio and display receiver assembly*4 connector.

    13. Connect the K62 certification ECU (smart key ECU assembly)*5 connector.

    14. Connect the K17 navigation ECU*6 connector.

    15. Connect the K10 stereo component amplifier assembly*7 connector.


      • *1: for A25A-FKS

      • *2: for 2GR-FKS

      • *3: for 2AR-FE

      • *4: w/ No. 1 Stereo Jack Adapter Assembly

      • *5: w/ Smart Entry and Start System

      • *6: w/ Navigation System

      • *7: for 9 Speakers

      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. CONFIRM MODEL


    1. Choose the model to be inspected.

      Result
      Result Proceed to
      w/ Navigation System A
      w/o Navigation System B

    B

    GO TO STEP 8 Click here

    A

  7. INSPECT NAVIGATION ECU (SHORT CIRCUIT IN NAVIGATION ECU)


    1. Disconnect the K17 navigation ECU connector.

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      K21-6 (+S) - Body ground Ignition switch ON 11 to 14 V

      Tech Tips

      If the result is as specified, there may be a short circuit in the navigation ECU.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE NAVIGATION ECU Click here

    NG

  8. CONFIRM MODEL


    1. Choose the model to be inspected.

      Result
      Result Proceed to
      w/ No. 1 Stereo Jack Adapter Assembly A
      w/o No. 1 Stereo Jack Adapter Assembly B

    B

    GO TO STEP 10 Click here

    A

  9. INSPECT RADIO AND DISPLAY RECEIVER ASSEMBLY (SHORT CIRCUIT IN RADIO AND DISPLAY RECEIVER ASSEMBLY)


    1. Disconnect the K3 radio and display receiver assembly connector.

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      K21-6 (+S) - Body ground Ignition switch ON 11 to 14 V

      Tech Tips

      If the result is as specified, there may be a short circuit in the radio and display receiver assembly.

      Result
      Result
      OK
      NG

    OK

    REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY Click here

    NG

  10. CONFIRM MODEL


    1. Choose the model to be inspected.

      Result
      Result Proceed to
      for 9 Speakers A
      except 9 Speakers B

    B

    GO TO STEP 12 Click here

    A

  11. INSPECT STEREO COMPONENT AMPLIFIER ASSEMBLY (SHORT CIRCUIT IN STEREO COMPONENT AMPLIFIER ASSEMBLY)


    1. Disconnect the K10 stereo component amplifier assembly connector.

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      K21-6 (+S) - Body ground Ignition switch ON 11 to 14 V

      Tech Tips

      If the result is as specified, there may be a short circuit in the stereo component amplifier assembly.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE STEREO COMPONENT AMPLIFIER ASSEMBLY Click here

    NG

  12. CONFIRM MODEL


    1. Choose the model to be inspected.

      Result
      Result Proceed to
      w/ Smart Entry and Start System A
      w/o Smart Entry and Start System B

    B

    REPLACE ECM for A25A-FKS: Click here
    REPLACE ECM for 2GR-FKS: Click here
    REPLACE ECM for 2AR-FE: Click here

    A

  13. INSPECT CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) (SHORT CIRCUIT IN CERTIFICATION ECU (SMART KEY ECU ASSEMBLY))


    1. Disconnect the K62 certification ECU (smart key ECU assembly) connector.

    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage
      Tester Connection Condition Specified Condition
      K21-6 (+S) - Body ground Ignition switch ON 11 to 14 V

      Tech Tips

      If the result is as specified, there may be a short circuit in the certification ECU (smart key ECU assembly).

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

    NG

    REPLACE ECM for A25A-FKS: Click here
    REPLACE ECM for 2GR-FKS: Click here
    REPLACE ECM for 2AR-FE: Click here