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*a. 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

B004OSTE01

CAUTION / NOTICE / HINT

Note

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

PROCEDURE


  1. INSPECT ECU TERMINAL VOLTAGE (INPUT VOLTAGE)


    1. Disconnect the F6 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
      F6-19 (+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 (meter circuit plate), the combination meter assembly (meter circuit plate) will output a waveform.

      Result
      Result Proceed to
      OK A
      NG (for LHD) B
      NG (for RHD) C

    B

    CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY (METER CIRCUIT PLATE) - NO. 8 JUNCTION CONNECTOR) Click here

    C

    CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY (METER CIRCUIT PLATE) - NO. 17 JUNCTION CONNECTOR) Click here

    A

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


    1. Reconnect the F6 combination meter assembly (meter circuit plate) connector.

    2. Disconnect the A41 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
      A41-11 (SP1) - Body ground Power switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

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

    OK

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


    1. B004QZWC33
      *a

      Component with harness connected

      (Combination Meter Assembly (Meter Circuit Plate))

      Check the input waveform.


      1. Reconnect the A41 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 F6-20 (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
        Tool setting 5 V/DIV., 20 ms./DIV.
        Vehicle 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 (COMBINATION METER ASSEMBLY (METER CIRCUIT PLATE) - SKID CONTROL ECU (BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY))


    1. Disconnect the F6 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
      F6-20 (SI) - A41-11 (SP1) Always Below 1 Ω
      F6-20 (SI) or A41-11 (SP1) - 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. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY (METER CIRCUIT PLATE) - NO. 8 JUNCTION CONNECTOR)


    1. Disconnect the F79 No. 8 junction connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      F6-19 (+S) - F79-7 Always Below 1 Ω
      F6-19 (+S) or F79-7 - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. CHECK HARNESS AND CONNECTOR (NO. 8 JUNCTION CONNECTOR)


    1. Check for a short in the wire harness and connectors connected to the No. 8 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.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      F79-9 - Body ground*1 Power switch on (IG) 4.5 to 14 V
      F79-10 - Body ground*2 Power switch on (IG) 4.5 to 14 V
      F79-11 - Body ground Power switch on (IG) 4.5 to 14 V

      • *1: for 10 Speakers

      • *2: for Radio and Display Type or Navigation Receiver Type

      Result
      Result Proceed to
      Voltage is not present in one circuit. A
      Voltage is present in all of the circuits. B

    B

    REPLACE NO. 8 JUNCTION CONNECTOR (INSTRUMENT PANEL WIRE)

    A

  7. SYSTEM CHECK


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

      Result
      Result System that uses the circuit Proceed to
      F79-11 - Body ground Entry and start system A
      F79-10 - Body ground Audio and visual system*1 B
      Navigation system*2 C
      F79-9 - Body ground Navigation system*3 D

      • *1: for Radio and Display Type

        *2: for Navigation Receiver Type

        *3: for 10 Speakers


    B

    CHECK HARNESS AND CONNECTOR (RADIO AND DISPLAY RECEIVER ASSEMBLY - BODY GROUND) Click here

    C

    CHECK HARNESS AND CONNECTOR (NAVIGATION RECEIVER ASSEMBLY - BODY GROUND) Click here

    D

    CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER ASSEMBLY - BODY GROUND) Click here

    A

  8. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) - BODY GROUND)


    1. Disconnect the F1 certification ECU (smart key ECU assembly) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      F1-19 (SPD) or F79-11 - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  9. CHECK HARNESS AND CONNECTOR (RADIO AND DISPLAY RECEIVER ASSEMBLY - BODY GROUND)


    1. Disconnect the F31 radio and display receiver assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      F31-17 (SPD) or F79-10 - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  10. CHECK HARNESS AND CONNECTOR (NAVIGATION RECEIVER ASSEMBLY - BODY GROUND)


    1. Disconnect the F92 navigation receiver assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      F92-17 (SPD) or F79-10 - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE NAVIGATION RECEIVER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  11. CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER ASSEMBLY - BODY GROUND)


    1. Disconnect the F61 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
      F61-11 (SPD) or F79-9 - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE STEREO COMPONENT AMPLIFIER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  12. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY (METER CIRCUIT PLATE) - NO. 17 JUNCTION CONNECTOR)


    1. Disconnect the F85 No. 17 junction connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      F6-19 (+S) - F85-16 Always Below 1 Ω
      F6-19 (+S) or F85-16 - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  13. CHECK HARNESS AND CONNECTOR (NO. 17 JUNCTION CONNECTOR)


    1. Check for a short in the wire harness and connectors connected to the No. 17 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.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      F85-17 - Body ground*1 Power switch on (IG) 4.5 to 14 V
      F85-18 - Body ground*2 Power switch on (IG) 4.5 to 14 V
      F85-19 - Body ground Power switch on (IG) 4.5 to 14 V

      • *1: for 10 Speakers

      • *2: for Radio and Display Type or Navigation Receiver Type

      Result
      Result Proceed to
      Voltage is not present in one circuit. A
      Voltage is present in all of the circuits. B

    B

    REPLACE NO. 17 JUNCTION CONNECTOR (INSTRUMENT PANEL WIRE)

    A

  14. SYSTEM CHECK


    1. Select the circuit for which voltage was not present in step 13.

      Result
      Result System that uses the circuit Proceed to
      F85-19 - Body ground Entry and start system A
      F85-18 - Body ground Audio and visual system*1 B
      Navigation system*2 C
      F85-17 - Body ground*3 Audio and visual system*1 or Navigation system*2 D

      • *1: for Radio and Display Type

        *2: for Navigation Receiver Type

        *3: for 10 Speakers


    A

    GO TO STEP 8 Click here

    B

    GO TO STEP 9 Click here

    C

    GO TO STEP 10 Click here

    D

    GO TO STEP 11 Click here