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 sensor signal*a. The vehicle speed sensor 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

A0004TSE04

PROCEDURE


  1. INSPECT COMBINATION METER ASSEMBLY (INPUT VOLTAGE)


    1. A0007JXE01
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Combination Meter Assembly)

      Disconnect the H14 combination meter assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      H14-19 (+S) - Body ground Power 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.


    NG

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

    OK

  2. INSPECT COMBINATION METER ASSEMBLY (OUTPUT VOLTAGE)


    1. Reconnect the H14 combination meter assembly connector.

    2. A0005SVE01
      Text in Illustration
      *a

      Front view of wire harness connector

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

      Disconnect the A24 skid control ECU connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A24-11 (SP1) - Body ground Power switch on (IG) 11 to 14 V

    NG

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

    OK

  3. INSPECT SKID CONTROL ECU (INPUT WAVEFORM)


    1. A0004V2E01
      Text in Illustration
      *a

      Component with harness connected

      (Combination Meter Assembly)

      Check the input waveform.


      1. Reconnect the A24 skid control ECU connector.

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

      3. Connect an oscilloscope to terminal H14-20 (SI) and body ground.

      4. Turn the power switch on (IG).

      5. Turn the wheel slowly.

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

        Item Condition
        Tool setting 5 V/DIV., 20 ms./DIV.
        Vehicle condition 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
        Result Proceed to
        OK A
        NG (for LHD) B
        NG (for RHD) C

    A

    REPLACE COMBINATION METER ASSEMBLY Click here

    B

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SKID CONTROL ECU) Click here

    C

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SKID CONTROL ECU) Click here

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


    1. Disconnect the H14 combination meter assembly connector.

    2. Disconnect the A24 skid control ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H14-20 (SI) - A24-11 (SP1) Always Below 1 Ω
      H14-20 (SI) - Body ground Always 10 kΩ or higher

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

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


    1. Disconnect the H115*1 or H114*2 junction connector.


      • *1: for LHD

      • *2: for RHD

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H14-19 (+S) - H115-20*1 Always Below 1 Ω
      H14-19 (+S) - H114-12*2 Always Below 1 Ω
      H14-19 (+S) - Body ground Always 10 kΩ or higher

      • *1: for LHD

      • *2: for RHD


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. CHECK HARNESS AND CONNECTOR (JUNCTION CONNECTOR)


    1. Inspect for a short in the wire harness and connectors connected to the junction connector shown in the wiring diagram.

      Tech Tips

      If voltage is not present, it is possible that an ECU or circuit has a malfunction. The malfunctioning ECU or circuit will be diagnosed in the following steps.


      1. Disconnect the H114 and H115 junction connectors.

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

        Standard Voltage
        Tester Connection Condition Specified Condition
        H114-13 - Body ground Power switch on (IG) 4.5 to 14 V
        H114-14 - Body ground Power switch on (IG) 4.5 to 14 V
        H114-15 - Body ground Power switch on (IG) 4.5 to 14 V
        H115-19 - Body ground Power switch on (IG) 4.5 to 14 V
        H115-21 - Body ground Power switch on (IG) 4.5 to 14 V
        Result
        Result Proceed to
        Voltage is not present in one circuit. A
        Voltage is present in all of the circuits. B

    B

    REPLACE JUNCTION CONNECTOR (INSTRUMENT PANEL WIRE)

    A

  7. SYSTEM CHECK


    1. Select the circuit for which voltage was not present in step 6.

      Result
      Tester Connection System that uses the circuit Proceed to
      H114-13 - Body ground Auto wiper system*1 A
      H114-14 - Body ground Smart entry and start system B
      H114-15 - Body ground Audio and visual system*2 or Navigation system*3 C
      H115-19 - Body ground Automatic headlight beam level control system D
      H115-21 - Body ground Audio and visual system*2 or Navigation system*3 E

      • *1: w/ Auto wiper system

      • *2: for Radio and display type

      • *3: for Navigation receiver type


    B

    CHECK HARNESS AND CONNECTOR (POWER MANAGEMENT CONTROL ECU CIRCUIT) Click here

    C

    CHECK HARNESS AND CONNECTOR (RADIO RECEIVER ASSEMBLY CIRCUIT, MULTI-MEDIA MODULE RECEIVER ASSEMBLY CIRCUIT) Click here

    D

    CHECK HARNESS AND CONNECTOR (HEADLIGHT LEVELING ECU ASSEMBLY CIRCUIT) Click here

    E

    CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER ASSEMBLY CIRCUIT) Click here

    A

  8. CHECK HARNESS AND CONNECTOR (WINDSHIELD WIPER RELAY ASSEMBLY CIRCUIT)


    1. Disconnect the H51 windshield wiper relay assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H51-24 (SPD) - Body ground Always 10 kΩ or higher

    OK

    REPLACE WINDSHIELD WIPER RELAY ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  9. CHECK HARNESS AND CONNECTOR (POWER MANAGEMENT CONTROL ECU CIRCUIT)


    1. Disconnect the H1 power management control ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H1-14 (SPDI) - Body ground Always 10 kΩ or higher

    OK

    REPLACE POWER MANAGEMENT CONTROL ECU Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  10. CHECK HARNESS AND CONNECTOR (RADIO RECEIVER ASSEMBLY CIRCUIT, MULTI-MEDIA MODULE RECEIVER ASSEMBLY CIRCUIT)


    1. Disconnect the H176 radio receiver assembly*1 or H97 multi-media module receiver assembly*2 connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H176-17 (SPD)*1 - Body ground Always 10 kΩ or higher
      H97-56 (SPD)*2 - 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

    A

    REPLACE RADIO RECEIVER ASSEMBLY Click here

    B

    REPLACE MULTI-MEDIA MODULE RECEIVER ASSEMBLY Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  11. CHECK HARNESS AND CONNECTOR (HEADLIGHT LEVELING ECU ASSEMBLY CIRCUIT)


    1. Disconnect the A29 headlight leveling ECU assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A29-16 (SPDR) - Body ground Always 10 kΩ or higher

    OK

    REPLACE HEADLIGHT LEVELING ECU ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  12. CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER ASSEMBLY CIRCUIT)


    1. Disconnect the H99*1 or H87*2 stereo component amplifier assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      H99-17 (SPD)*1 - Body ground Always 10 kΩ or higher
      H87-11 (SPD)*2 - Body ground Always 10 kΩ or higher

      • *1: for Navigation receiver type

      • *2: for Radio and display type


    OK

    REPLACE STEREO COMPONENT AMPLIFIER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR