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 which uses this information to create the vehicle speed signal*a. The vehicle speed signal consists of pulses sent to the combination meter assembly from the skid control ECU. 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. The pulse signal is created by switching the transistor in the skid control ECU 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 or 5 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. 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

B006FUAE03

CAUTION / NOTICE / HINT

Note


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

  • 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.

PROCEDURE


  1. CHECK ECU TERMINAL VOLTAGE (INPUT VOLTAGE)


    1. Disconnect the G34 combination meter assembly connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      G34-19 (+S) - Body ground Engine switch on (IG) 4.5 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 (COMBINATION METER ASSEMBLY - EACH ECU) Click here

    OK

  2. CHECK COMBINATION METER ASSEMBLY (OUTPUT VOLTAGE)


    1. Reconnect the G34 combination meter assembly connector.

    2. Disconnect the A9*1 or A11*2 skid control ECU connector.


      • *1: w/ Vacuum Brake Booster

      • *2: w/o Vacuum Brake Booster

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

      Standard Voltage
      w/ Vacuum Brake Booster:
      Tester Connection Switch Condition Specified Condition
      A9-14 (SP1) - Body ground Engine switch on (IG) 11 to 14 V
      w/o Vacuum Brake Booster:
      Tester Connection Switch Condition Specified Condition
      A11-22 (SP1) - Body ground Engine switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

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

    OK

  3. CHECK COMBINATION METER ASSEMBLY (INPUT WAVEFORM)


    1. B006H14C98
      *a

      Component with harness connected

      (Combination Meter Assembly)

      Check the input waveform.


      1. Reconnect the A9*1 or A11*2 skid control ECU connector.


        • *1: w/ Vacuum Brake Booster

        • *2: w/o Vacuum Brake Booster

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

      3. Connect an oscilloscope to terminal G34-20 (SI) and body ground.

      4. Turn the engine switch on (IG).

      5. Turn a wheel slowly.

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

        Item Condition
        Tester Connection G34-20 (SI)
        Tool setting 5 V/DIV., 20 ms./DIV.
        Vehicle condition Engine switch on (IG) 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 A
      NG (w/ Vacuum Brake Booster) B
      NG (w/o Vacuum Brake Booster) C

    A

    REPLACE COMBINATION METER ASSEMBLY Click here

    B

    REPLACE BRAKE ACTUATOR ASSEMBLY for LHD: REPLACE BRAKE ACTUATOR ASSEMBLY Click here
    REPLACE BRAKE ACTUATOR ASSEMBLY for RHD: REPLACE BRAKE ACTUATOR ASSEMBLY Click here

    C

    REPLACE SKID CONTROL ECU ASSEMBLY Click here

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


    1. Disconnect the G34 combination meter assembly connector.

    2. Disconnect the A9*1 or A11*2 skid control ECU connector.


      • *1: w/ Vacuum Brake Booster

      • *2: w/o Vacuum Brake Booster

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

      Standard Resistance
      w/ Vacuum Brake Booster:
      Tester Connection Condition Specified Condition
      G34-20 (SI) - A9-14 (SP1) Always Below 1 Ω
      G34-20 (SI) - Other terminals and body ground Always 10 kΩ or higher
      w/o Vacuum Brake Booster:
      Tester Connection Condition Specified Condition
      G34-20 (SI) - A11-22 (SP1) Always Below 1 Ω
      G34-20 (SI) - Other terminals and 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 (COMBINATION METER ASSEMBLY - EACH ECU)


    • *1: for 8GR-FKS

    • *2: for V35A-FTS

    • *3: w/ Telematics Transceiver


    1. Disconnect the G71 certification ECU (smart key ECU assembly) connector.

    2. Disconnect the L52 stereo component amplifier assembly connector.

    3. Disconnect the A56*1 or A95*2 ECM connector.

    4. Disconnect the G55 navigation ECU connector.

    5. Disconnect the G52 radio receiver assembly connector.

    6. Disconnect the G56 telematics transceiver connector.*3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      G34-19 (+S) - Other terminals and body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. CHECK ECM (SHORT CIRCUIT IN ECM)


    1. Reconnect the G71 certification ECU (smart key ECU assembly) connector.

    2. Reconnect the L52 stereo component amplifier assembly connector.

    3. Reconnect the G55 navigation ECU connector.

    4. Reconnect the G52 radio receiver assembly connector.

    5. Reconnect the G56 telematics transceiver connector.*


      • *: w/ Telematics Transceiver

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      G34-19 (+S) - Body ground Engine switch on (IG) 4.5 to 14 V

      Tech Tips

      If the result is as specified, there may be a short circuit in the vehicle approaching speaker assembly.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ECM for 8GR-FKS: REPLACE ECM Click here
    REPLACE ECM for V35A-FTS: REPLACE ECM Click here

    NG

  7. CHECK RADIO RECEIVER ASSEMBLY (SHORT CIRCUIT IN RADIO RECEIVER)


    1. Reconnect the G52 radio receiver assembly connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      G34-19 (+S) - Body ground Engine switch on (IG) 4.5 to 14 V

      Tech Tips

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

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE RADIO RECEIVER ASSEMBLY Click here

    NG

  8. CHECK STEREO COMPONENT AMPLIFIER ASSEMBLY (SHORT CIRCUIT IN STEREO COMPONENT AMPLIFIER)


    1. Reconnect the L52 stereo component amplifier assembly connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      G34-19 (+S) - Body ground Engine switch on (IG) 4.5 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

  9. CHECK NAVIGATION ECU (SHORT CIRCUIT IN NAVIGATION ECU)


    1. Disconnect the G55 navigation ECU connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      G34-19 (+S) - Body ground Engine switch on (IG) 4.5 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

  10. CHECK CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) (SHORT CIRCUIT IN CERTIFICATION ECU (SMART KEY ECU ASSEMBLY))


    1. Reconnect the G71 certification ECU (smart key ECU assembly) connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      G34-19 (+S) - Body ground Engine switch on (IG) 4.5 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 TELEMATICS TRANSCEIVER Click here