METER / GAUGE SYSTEM Speed Signal Circuit

DESCRIPTION

The combination meter assembly (No. 3 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 which uses this information to create the vehicle speed sensor signal*1. 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 the pulse signal.


Tech Tips

This circuit is used for the systems connected to terminal +S. This signal is not used for combination meter assembly (no. 3 meter circuit plate) operation. Combination meter assembly components such as the speedometer operate using data received via CAN communication.

WIRING DIAGRAM

A00432RE01

INSPECTION PROCEDURE

PROCEDURE


  1. INSPECT ECU TERMINAL VOLTAGE (INPUT VOLTAGE)


    1. A0041SHE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Combination Meter Assembly)

      Disconnect the L23 combination meter assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      L23-7 (+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 - RADIO AND DISPLAY RECEIVER ASSEMBLY, NAVIGATION ECU SUB-ASSEMBLY) Click here

    OK

  2. INSPECT COMBINATION METER ASSEMBLY (OUTPUT VOLTAGE)


    1. Reconnect the L23 combination meter assembly connector.

    2. A00403IE02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Skid Control ECU)

      Disconnect the A57 skid control ECU connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A57-11 (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. A0041DYE09
      Text in Illustration
      *a

      Component with harness connected

      (Combination Meter Assembly)

      Check the input waveform.


      1. Reconnect the A57 skid control ECU connector.

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

      3. Connect an oscilloscope to terminal L23-8 (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 Driving at approx. 20 km/h (12 mph)
        OK
        The waveform is displayed as 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

    B

    REPLACE SKID CONTROL ECU Click here

    C

    REPLACE SKID CONTROL ECU Click here

    A

    REPLACE NO. 3 METER CIRCUIT PLATE Click here

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


    1. Disconnect the L23 combination meter assembly and A57 skid control ECU connectors.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A57-11 (SP1) - L23-8 (SI) Always Below 1 Ω
      A57-11 (SP1) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE NO. 3 METER CIRCUIT PLATE Click here

  5. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - RADIO AND DISPLAY RECEIVER ASSEMBLY, NAVIGATION ECU SUB-ASSEMBLY)


    1. Disconnect the L23 combination meter assembly and L27*1 navigation ECU sub-assembly or L107*2 radio and display receiver assembly connectors.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      L27-17 (SPD)*1 - L23-7 (+S) Always Below 1 Ω
      L107-17 (SPD)*2 - L23-7 (+S) Always Below 1 Ω
      L23-7 (+S) - Body ground Always 10 kΩ or higher

      • *1: for Navigation Receiver Type

      • *2: for Radio and Display Type


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. INSPECT NAVIGATION ECU SUB-ASSEMBLY, RADIO AND DISPLAY RECEIVER ASSEMBLY (OUTPUT VOLTAGE)


    1. Reconnect the L27*1 navigation ECU sub-assembly or L107*2 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
      L27-17 (SPD)*1 - Body ground Power switch on (IG) 4.5 to 14 V
      L107-17 (SPD)*2 - Body ground Power switch on (IG) 4.5 to 14 V

      • *1: for Navigation Receiver Type

      • *2: for Radio and Display Type

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

    B

    REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY Click here

    C

    REPLACE NAVIGATION ECU SUB-ASSEMBLY Click here

    A

  7. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - NO. 3 JUNCTION BLOCK)


    1. Disconnect the 3A junction block connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      L23-7 (+S) - 3A-26*1 Always Below 1 Ω
      L23-7 (+S) - 3A-47*2 Always Below 1 Ω
      L23-7 (+S) - Body ground Always 10 kΩ or higher

      • *1: for LHD

      • *2: for RHD


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  8. CHECK HARNESS AND CONNECTOR (NO. 3 JUNCTION BLOCK)


    1. Inspect for a short in the circuit that is connected to the junction block 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 3B junction block connector.

        A00414YE12

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

        Standard Voltage
        Tester Connection Condition Specified Condition
        3A-2*1 - Body ground Power switch on (IG) 4.5 to 14 V
        3B-85*1 - Body ground Power switch on (IG) 4.5 to 14 V
        3A-9*2 - Body ground Power switch on (IG) 4.5 to 14 V
        3B-82*2 - Body ground Power switch on (IG) 4.5 to 14 V

        • *1: for LHD

        • *2: for RHD

        Text in Illustration
        *a

        Front view of wire harness connector

        (to No. 3 Junction Block)
        Result
        Result Proceed to
        Voltage is not present in one circuit. A
        Voltage is present in all the circuits. B

    B

    REPLACE NO. 3 JUNCTION BLOCK (INSTRUMENT PANEL WIRE)

    A

  9. CHECK HARNESS AND CONNECTOR (NO. 3 JUNCTION BLOCK - NO. 4 JUNCTION BLOCK)


    1. Disconnect the 4A junction block connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      3B-85*1 - 4A-21 Always Below 1 Ω
      3B-85*1 - Body ground Always 10 kΩ or higher
      3B-82*2 - 4A-21 Always Below 1 Ω
      3B-82*2 - Body ground Always 10 kΩ or higher

      • *1: for LHD

      • *2: for RHD


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  10. CHECK HARNESS AND CONNECTOR (NO. 4 JUNCTION BLOCK)


    1. Inspect for a short in the circuit that is connected to the junction block 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. Measure the voltage according to the value(s) in the table below.

        A00441GE06
        Standard Voltage
        Tester Connection Condition Specified Condition
        4A-56 - Body ground Power switch on (IG) 4.5 to 14 V
        4A-69 - Body ground Power switch on (IG) 4.5 to 14 V
        Text in Illustration
        *a

        Front view of wire harness connector

        (to No. 4 Junction Block)
        Result
        Result Proceed to
        Voltage is not present in one circuit. A
        Voltage is present in all the circuits. B

    B

    REPLACE NO. 4 JUNCTION BLOCK (INSTRUMENT PANEL WIRE)

    A

  11. SYSTEM CHECK


    1. Select the circuit for which voltage was not present in step 10.

      Result
      Tester Connection System that Uses the Circuit Proceed to
      3A-2*1 - Body ground Entry and Start System A
      3A-9*2 - Body ground
      4A-69 - Body ground Audio/Visual System B
      4A-56*3 - Body ground Lighting System C

      • *1: for LHD

      • *2: for RHD

      • *3: w/ Automatic headlight beam level control system


    B

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

    C

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

    A

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


    1. Disconnect the L5 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
      L5-14 (SPDI) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE POWER MANAGEMENT CONTROL ECU Click here

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


    1. Disconnect the L69 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
      L69-11 (SPD) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE STEREO COMPONENT AMPLIFIER ASSEMBLY Click here

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


    1. Disconnect the A63 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
      A63-16 (SPDR) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE HEADLIGHT LEVELING ECU ASSEMBLY Click here

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


    1. Disconnect the L63 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
      L63-19 (SPD) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE WINDSHIELD WIPER RELAY ASSEMBLY