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 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 from the skid control ECU assembly. 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 assembly. The pulse signal is created by switching the transistor in the skid control ECU 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 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 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 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

B000R9ME04

CAUTION / NOTICE / HINT

Note


  • Before replacing the ECM or certification ECU (smart key ECU assembly) refer to Service Bulletin.

  • When replacing the combination meter assembly, always replace it with a new one. If a combination meter assembly which was installed to another vehicle is used, the information stored in it will not match the information from the vehicle and a DTC may be stored.

PROCEDURE


  1. INSPECT ECU TERMINAL VOLTAGE (INPUT VOLTAGE)


    1. B000Q6DC52
      *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
      P25-19 (+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.

      Result
      Proceed to
      OK
      NG

    NG

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

    OK

  2. INSPECT COMBINATION METER ASSEMBLY (OUTPUT VOLTAGE)


    1. Reconnect the P25 combination meter assembly connector.

    2. B000O58C02
      *a

      Front view of wire harness connector

      (to Skid Control ECU Assembly)

      Disconnect the skid control ECU assembly connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A9-22 (SP1) - Body ground Power switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

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

    OK

  3. INSPECT COMBINATION METER ASSEMBLY (INPUT WAVEFORM)


    1. B000OTSC86
      *a

      Component with harness connected

      (Combination Meter Assembly)

      Check the input waveform.


      1. Reconnect the A39 skid control ECU assembly connector.

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

      3. Connect an oscilloscope to terminal P25-20 (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 Click here

    NG

    REPLACE SKID CONTROL ECU ASSEMBLY for KHD: Click here
    REPLACE SKID CONTROL ECU ASSEMBLY for RHD: Click here

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


    1. Disconnect the P25 combination meter assembly connector.

    2. Disconnect the A9 skid control ECU assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      P25-20 (SI) - A9-22 (SP1) Always Below 1 Ω
      P25-20 (SI) - Other terminals and 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)


    1. Disconnect the P66 certification ECU (smart key ECU assembly) connector.

    2. Disconnect the X49 stereo component amplifier assembly connector.

    3. Disconnect the X51 vehicle approaching speaker assembly connector.

    4. Disconnect the P49 navigation ECU connector.

    5. Disconnect the P43 radio receiver assembly connector.

    6. Disconnect the Z2 map light sub-assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      P25-19 (+S) - Other terminals and body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. INSPECT VEHICLE APPROACHING SPEAKER ASSEMBLY (SHORT CIRCUIT IN VEHICLE APPROACHING SPEAKER ASSEMBLY)


    1. Disconnect the P66 certification ECU (smart key ECU assembly) connector.

    2. Disconnect the X49 stereo component amplifier assembly connector.

    3. Disconnect the P49 navigation ECU connector.

    4. Disconnect the Z2 map light sub-assembly connector.

    5. Disconnect the P43 radio receiver assembly connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      P25-19 (+S) - Body ground Power switch on (IG) 4.5 to 14 V

      Tech Tips

      If the result is as specified, there may be a short circuit in the vehicle approaching speaker assembly.

      Result
      Result Proceed to
      OK A
      NG B

    A

    REPLACE VEHICLE APPROACHING SPEAKER ASSEMBLY

    B

  7. INSPECT RADIO RECEIVER ASSEMBLY (SHORT CIRCUIT IN RADIO RECEIVER)


    1. Disconnect the P43 radio receiver assembly connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      P25-19 (+S) - Body ground Power 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

    NG

  8. INSPECT STEREO COMPONENT AMPLIFIER ASSEMBLY (SHORT CIRCUIT IN STEREO COMPONENT AMPLIFIER)


    1. Disconnect the X49 stereo component amplifier assembly connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      P25-19 (+S) - Body ground Power 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

    NG

  9. INSPECT NAVIGATION ECU (SHORT CIRCUIT IN NAVIGATION ECU)


    1. Disconnect the P49 navigation ECU connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      P25-19 (+S) - Body ground Power switch on (IG) 4.5 to 14 V

      Tech Tips

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

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE NAVIGATION ECU

    NG

  10. INSPECT MAP LIGHT SUB-ASSEMBLY (SHORT CIRCUIT IN NAVIGATION ECU)


    1. Disconnect the Z2 map light sub-assembly connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      P25-19 (+S) - Body ground Power switch on (IG) 4.5 to 14 V

      Tech Tips

      If the result is as specified, there may be a short circuit in the map light sub-assembly.

      Result
      Proceed to
      OK
      NG

    OK

    REPLACE MAP LIGHT SUB-ASSEMBLY

    NG

    REPLACE CERTIFICATION ECU (SMART KEY ECU ASSEMBLY)