METER / GAUGE SYSTEM Speed Signal Circuit

DESCRIPTION

The combination meter assembly (meter circuit plate) 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 booster with master cylinder assembly) which uses this information to create the vehicle speed signal*. The vehicle speed signal consists of pulses sent to the combination meter assembly (meter circuit plate) from the skid control ECU (brake booster with master cylinder assembly). To create this signal, 12 V is output from IG2 which is behind a resistor in the combination meter assembly (meter circuit plate). This voltage is sent to the skid control ECU (brake booster with master cylinder assembly). The pulse signal is created by switching the transistor in the skid control ECU (brake booster with master cylinder 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 (meter circuit plate) 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 (meter circuit plate) is controlled by the signal from the skid control ECU (brake booster with master cylinder 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 (meter circuit plate) 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 (meter circuit plate) operation. Combination meter assembly (Meter circuit plate) components such as the speedometer operate using data received via CAN communication.

WIRING DIAGRAM

A003N28E03

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 certification ECU (smart key ECU assembly), refer to Service Bulletin.

PROCEDURE


  1. INSPECT ECU TERMINAL VOLTAGE (INPUT VOLTAGE)

    A003OLIC46
    *a

    Front view of wire harness connector

    (to Combination Meter Assembly (Meter Circuit Plate))

    1. Disconnect the I6 combination meter assembly (meter circuit plate) connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      I6-19 (+S) - Body ground Power switch on (IG) 11 to 14 V

      Tech Tips

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

      Result
      Proceed to
      OK
      NG

    NG

    CONFIRM MODEL Click here

    OK

  2. INSPECT COMBINATION METER ASSEMBLY (METER CIRCUIT PLATE) (OUTPUT VOLTAGE)

    B006HQOC36
    *a

    Front view of wire harness connector

    (to Skid Control ECU (Brake Booster with Master Cylinder Assembly))

    1. Connect the I6 combination meter assembly (meter circuit plate) connector.

    2. Disconnect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A32-11 (SP1) - Body ground Power switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) - COMBINATION METER ASSEMBLY (METER CIRCUIT PLATE)) Click here

    OK

  3. INSPECT SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) (INPUT WAVEFORM)

    A003LNWC37
    *a

    Component with harness connected

    (Combination Meter Assembly (Meter Circuit Plate))

    1. Check the input waveform.


      1. Connect the A32 skid control ECU (brake booster with master cylinder assembly) connector.

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

      3. Connect an oscilloscope to terminal I6-20 (SI) and body ground.

      4. Turn the power 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 I6-20 (SI) - Body ground
        Tool setting 5 V/DIV., 20 ms./DIV.
        Condition Power 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
      NG

    OK

    REPLACE COMBINATION METER ASSEMBLY (METER CIRCUIT PLATE) Click here

    NG

    REPLACE SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) for LHD: Click here
    REPLACE SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) for RHD: Click here

  4. CHECK HARNESS AND CONNECTOR (SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY) - COMBINATION METER ASSEMBLY (METER CIRCUIT PLATE))


    1. Disconnect the I6 combination meter assembly (meter circuit plate) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A32-11 (SP1) - I6-20 (SI) Always Below 1 Ω
      A32-11 (SP1) or I6-20 (SI) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE COMBINATION METER ASSEMBLY (METER CIRCUIT PLATE) Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  5. CONFIRM MODEL


    1. Choose the model to be inspected.

      Result
      Result Proceed to
      for 10 Speakers A
      except 10 Speakers B

    B

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

    A

  6. CHECK HARNESS AND CONNECTOR (EACH ECU - COMBINATION METER ASSEMBLY (METER CIRCUIT PLATE))


    1. Disconnect the I1 certification ECU (smart key ECU assembly) connector.

    2. Disconnect the I96 radio and display receiver assembly connector*1.

    3. Disconnect the I33 navigation receiver assembly connector*2.

    4. Disconnect the I64 stereo component amplifier assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I1-19 (SPD), I96-17 (SPD)*1, I33-17 (SPD)*2, I64-11 (SPD) or I6-19 (+S) - Body ground Always 10 kΩ or higher

      • *1: for Radio and Display Type

      • *2: for Navigation Receiver Type

      Result
      Result Proceed to
      OK (for Radio and Display Type) A
      OK (for Navigation Receiver Type) B
      NG C

    B

    INSPECT NAVIGATION RECEIVER ASSEMBLY (SHORT CIRCUIT IN NAVIGATION RECEIVER ASSEMBLY) Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    A

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


    1. Connect the I1 certification ECU (smart key ECU assembly) connector.

    2. Connect the I64 stereo component amplifier assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      I96-17 (SPD) or I6-19 (+S) - Body ground Power switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY Click here

    NG

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


    1. Disconnect the I64 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
      I64-11 (SPD), I96-17 (SPD) or I6-19 (+S) - Body ground Power switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE STEREO COMPONENT AMPLIFIER ASSEMBLY Click here

    NG

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

  9. INSPECT NAVIGATION RECEIVER ASSEMBLY (SHORT CIRCUIT IN NAVIGATION RECEIVER ASSEMBLY)


    1. Connect the I1 certification ECU (smart key ECU assembly) connector.

    2. Connect the I64 stereo component amplifier assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      I33-17 (SPD) or I6-19 (+S) - Body ground Power switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE NAVIGATION RECEIVER ASSEMBLY Click here

    NG

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


    1. Disconnect the I64 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
      I64-11 (SPD), I33-17 (SPD) or I6-19 (+S) - Body ground Power switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE STEREO COMPONENT AMPLIFIER ASSEMBLY Click here

    NG

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

  11. CHECK HARNESS AND CONNECTOR (EACH ECU - COMBINATION METER ASSEMBLY (METER CIRCUIT PLATE))


    1. Disconnect the I1 certification ECU (smart key ECU assembly) connector.

    2. Disconnect the I96 radio and display receiver assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      I1-19 (SPD), I96-17 (SPD) or I6-19 (+S) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

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


    1. Connect the I1 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
      I96-17 (SPD) or I6-19 (+S) - Body ground Power switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY Click here

    NG

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)