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 brake actuator assembly (skid control ECU) which uses this information to create the vehicle speed signal*a. The vehicle speed signal consists of pulses sent to the combination meter assembly from the brake actuator assembly (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 brake actuator assembly (skid control ECU). The pulse signal is created by switching the transistor in the brake actuator assembly (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 brake actuator assembly (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

B002EE9E02

CAUTION / NOTICE / HINT

Note

Before replacing the ECM or certification ECU (smart key ECU assembly) refer to Registration.


  • ECM: Click here

  • Certification ECU(smart key ECU assembly): Refer to Service Bulletin

PROCEDURE


  1. CHECK ECU TERMINAL VOLTAGE (INPUT VOLTAGE)


    1. B002CE5C31
      *a

      Front view of wire harness connector

      (to Combination Meter Assembly)

      Disconnect the combination meter assembly connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      K33-19 (+S) - Body ground Engine 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.

      Result
      Proceed to
      OK
      NG

    NG

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

    OK

  2. CHECK COMBINATION METER ASSEMBLY (OUTPUT VOLTAGE)


    1. Reconnect the K33 combination meter assembly connector.

    2. B002DGDC02
      *a

      Front view of wire harness connector

      (to Brake Actuator Assembly (Skid Control ECU))

      Disconnect the A52 brake actuator assembly (skid control ECU) connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A52-14 (SP1) - Body ground Engine switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

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

    OK

  3. CHECK BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU) (INPUT WAVEFORM)


    1. B002E5BC66
      *a

      Component with harness connected

      (Combination Meter Assembly)

      Check the input waveform.


      1. Reconnect the A52 brake actuator assembly (skid control ECU) connector.

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

      3. Connect an oscilloscope to terminal K33-20 (SI) and body ground.

      4. Turn the engine 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 Engine 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 Click here

    NG

    REPLACE BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU) for LHD: Click here
    REPLACE BRAKE ACTUATOR ASSEMBLY (SKID CONTROL ECU) for RHD: Click here

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


    1. Disconnect the K33 combination meter assembly connector.

    2. Disconnect the A52 brake actuator assembly (skid control ECU) connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      K33-20 (SI) - A52-14 (SP1) Always Below 1 Ω
      K33-20 (SI) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

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


    • *: w/ Telematics System


    1. Disconnect the A13 ECM connector.

    2. Disconnect the K74 certification ECU (smart key ECU assembly) connector.

    3. Disconnect the K57 radio receiver assembly connector.

    4. Disconnect the T32 stereo component amplifier assembly connector.

    5. Disconnect the K70 telematics transceiver connector.*

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      K33-19 (+S) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. CHECK ECM (SHORT CIRCUIT IN ECM)

    B002CE5C42
    *a

    Front view of wire harness connector

    (to Combination Meter Assembly)

    • *: w/ Telematics System


    1. Reconnect the K74 certification ECU (smart key ECU assembly) connector.

    2. Reconnect the K57 radio receiver assembly connector.

    3. Reconnect the T32 stereo component amplifier assembly connector.

    4. Reconnect the K70 telematics transceiver connector.*

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      K33-19 (+S) - Body ground Engine switch on (IG) 4.5 to 14 V

      Tech Tips

      If the result is as specified, there may be a short circuit in the ECM.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE ECM Click here

    NG

  7. CHECK TELEMATICS TRANSCEIVER (SHORT CIRCUIT IN TELEMATICS TRANSCEIVER)

    B002CE5C43
    *a

    Front view of wire harness connector

    (to Combination Meter Assembly)

    Note

    For vehicles without a telematics system, go to "RADIO RECEIVER ASSEMBLY (SHORT CIRCUIT IN RADIO RECEIVER ASSEMBLY)"


    1. Disconnect the A13 ECM connector.

    2. Reconnect the K74 certification ECU (smart key ECU assembly) connector.

    3. Reconnect the K57 radio receiver assembly connector.

    4. Reconnect the T32 stereo component amplifier assembly connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      K33-19 (+S) - Body ground Engine switch on (IG) 4.5 to 14 V

      Tech Tips

      If the result is as specified, there may be a short circuit in the telematics transceiver.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE TELEMATICS TRANSCEIVER Click here

    NG

  8. CHECK RADIO RECEIVER ASSEMBLY (SHORT CIRCUIT IN RADIO RECEIVER ASSEMBLY)

    B002CE5C45
    *a

    Front view of wire harness connector

    (to Combination Meter Assembly)

    • *: w/ Telematics System


    1. Reconnect the A13 ECM connector.

    2. Disconnect the K57 radio receiver assembly connector.

    3. Reconnect the K70 telematics transceiver connector.*

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      K33-19 (+S) - Body ground Engine switch on (IG) 4.5 to 14 V

      Tech Tips

      If the result is as specified, there may be a short circuit in the radio receiver assembly.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE RADIO RECEIVER ASSEMBLY Click here

    NG

  9. CHECK STEREO COMPONENT AMPLIFIER ASSEMBLY (SHORT CIRCUIT IN STEREO COMPONENT AMPLIFIER ASSEMBLY)

    B002CE5C44
    *a

    Front view of wire harness connector

    (to Combination Meter Assembly)

    • *: w/ Telematics System


    1. Reconnect the K57 radio receiver assembly connector.

    2. Disconnect the T32 stereo component amplifier assembly connector.

    3. Reconnect the K70 telematics transceiver connector.*

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      K33-19 (+S) - Body ground Engine switch on (IG) 4.5 to 14 V

      Tech Tips

      If the result is as specified, there may be a short circuit in the stereo component amplifier assembly.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE STEREO COMPONENT AMPLIFIER ASSEMBLY Click here

    NG

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY) Refer to Service Bulletin for installation position of the part.