METER / GAUGE SYSTEM Speed Signal Circuit

DESCRIPTION

The combination meter sub-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 sub-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 sub-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 sub-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 sub-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 sub-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 sub-assembly operation. Combination meter sub-assembly components such as the speedometer operate using data received via CAN communication.

WIRING DIAGRAM

A005A0EE02

PROCEDURE


  1. INSPECT ECU TERMINAL VOLTAGE (INPUT VOLTAGE)


    1. A005C8ME02
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Combination Meter Sub-assembly)

      Disconnect the L27 combination meter sub-assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified 0Condition
      L27-15 (+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 sub-assembly, the combination meter sub-assembly will output a waveform.


    NG
    OK
  2. INSPECT COMBINATION METER SUB-ASSEMBLY (OUTPUT VOLTAGE)


    1. Reconnect the L27 combination meter sub-assembly connector.

    2. A005BTZE01
      Text in Illustration
      *a

      Front view of wire harness connector

      (to Skid Control ECU)

      Disconnect the A58 skid control ECU connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A58-11 (SP1) - Body ground Power switch on (IG) 11 to 14 V

    NG
    OK
  3. INSPECT SKID CONTROL ECU (INPUT WAVEFORM)


    1. A005DC2E03

      Check the input waveform.


      1. Reconnect the A58 skid control ECU connector.

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

      3. Connect an oscilloscope to terminal L27-16 (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 Wheel being rotated

        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.

        OK
        The waveform is displayed as shown in the illustration.
        Text in Illustration
        *a

        Component with harness connected

        (Combination Meter Sub-assembly)

        Result
        Result Proceed to
        OK (w/o Multi-information display) A
        OK (w/ Multi-information display) B
        NG (for LHD) C
        NG (for RHD) D

    A
    B
    C
    D
  4. CHECK HARNESS AND CONNECTOR (COMBINATION METER SUB-ASSEMBLY - SKID CONTROL ECU)


    1. Disconnect the L27 combination meter sub-assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A58-11 (SP1) - L27-16 (SI) Always Below 1 Ω
      A58-11 (SP1) - Body ground Always 10 kΩ or higher
      Result
      Result Proceed to
      OK (w/o Multi-information display) A
      OK (w/ Multi-information display) B
      NG C

    A
    B
    C
  5. CHECK HARNESS AND CONNECTOR (COMBINATION METER SUB-ASSEMBLY - JUNCTION CONNECTOR)


    1. Disconnect the L70 junction connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      L27-15 (+S) - L70-32*1 Always Below 1 Ω
      L27-15 (+S) - L70-31*2 Always Below 1 Ω
      L27-15 (+S) - Body ground Always 10 kΩ or higher

      • *1: for LHD

      • *2: for RHD


    NG
    OK
  6. CHECK HARNESS AND CONNECTOR (JUNCTION CONNECTOR)


    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 L70 junction connector.

        A005B9VE02
      2. Measure the voltage according to the value(s) in the table below.

        Standard Voltage
        Tester Connection Condition Specified Condition
        L70-3 - Body ground Power switch on (IG) 4.5 to 14 V
        L70-11* - Body ground Power switch on (IG) 4.5 to 14 V
        L70-12 - Body ground Power switch on (IG) 4.5 to 14 V
        L70-21 - Body ground Power switch on (IG) 4.5 to 14 V
        L70-22 - Body ground Power switch on (IG) 4.5 to 14 V
        L70-31*1 - Body ground Power switch on (IG) 4.5 to 14 V
        L70-32*2 - Body ground Power switch on (IG) 4.5 to 14 V

        • *: for RHD

        Text in Illustration
        *a

        Front view of wire harness connector

        (to Junction Connector)

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

    B
    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
      L70-12*1 - Body ground Wiper and Washer System*3 A
      L70-21*2 - Body ground
      L70-22 - Body ground Hybrid Control System B
      L70-31*1 - Body ground Lighting System*4 C
      L70-32*2 - Body ground
      L70-21*1 - Body ground Audio and Visual System*5 D
      L70-11*2 - Body ground

      L70-3*1 - Body ground

      L70-1*1 - Body ground

      Audio and Visual System*6 E
      Navigation System*7
      L70-1*1 - Body ground Tire pressure warning system*8
      L70-3*2 - Body ground

      • *1: for LHD

      • *2: for RHD

      • *3: w/ Auto Wiper System

      • *4: w/ LED headlight

      • *5: for 8 speakers

      • *6: for Radio and display type

      • *7: for Navigation receiver type

      • *8: w/ Tire pressure warning system


    B
    C
    D
    E
    A
  8. CHECK HARNESS AND CONNECTOR (WINDSHIELD WIPER RELAY ASSEMBLY CIRCUIT)


    1. Disconnect the L146 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
      L146-24 (SPD) - Body ground Always 10 kΩ or higher

    OK
    NG
  9. CHECK HARNESS AND CONNECTOR (CERTIFICATION ECU (SMART KEY ECU ASSEMBLY CIRCUIT)


    1. Disconnect the L197 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
      L197-27 (SPD) - Body ground Always 10 kΩ or higher

    OK
    NG
  10. CHECK HARNESS AND CONNECTOR (HEADLIGHT LEVELING ECU ASSEMBLY CIRCUIT)


    1. Disconnect the A48 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
      A48-16 (SPDR) - Body ground Always 10 kΩ or higher

    OK
    NG
  11. CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER ASSEMBLY CIRCUIT)


    1. Disconnect the L31 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
      L31-11 (SPD) - Body ground Always 10 kΩ or higher

    OK
    NG
  12. 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

      L70-3*1 - Body ground

      L70-12*2 - Body ground

      Audio and Visual System*3 A
      Navigation System*4
      L70-1*1 - Body ground Tire Pressure Warning System*5 B
      L70-3*2 - Body ground

      • *1: for LHD

      • *2: for RHD

      • *3: for Radio and display type

      • *4: for Navigation receiver type

      • *5: w/ Tire pressure warning system


    B
    A
  13. CHECK HARNESS AND CONNECTOR (NAVIGATION RECEIVER ASSEMBLY CIRCUIT, RADIO AND DISPLAY RECEIVER ASSEMBLY CIRCUIT)


    1. Disconnect the L38 navigation receiver assembly*1 or L35 radio and display receiver assembly*2 connectors.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      L38-17 (SPD)*1 - Body ground Always 10 kΩ or higher
      L35-17 (SPD)*2 - Body ground Always 10 kΩ or higher

      • *1: for Navigation receiver type

      • *2: for Radio and display type

      Result
      Result Proceed to
      OK (for Navigation receiver type) A
      OK (for Radio and display type) B
      NG C

    A
    B
    C
  14. REPAIR HARNESS AND CONNECTOR (TIRE PRESSURE WARNING ECU AND RECEIVER CIRCUIT)


    1. Disconnect the R41 tire pressure warning ECU and receiver connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      R41-2 (SPD) - Body ground Always 10 kΩ or higher

    OK
    NG