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

WIRING DIAGRAM

A01NLPME01

INSPECTION PROCEDURE

PROCEDURE


  1. INSPECT ECU TERMINAL VOLTAGE (INPUT VOLTAGE)


    1. A01NMX7E04
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Combination Meter Assembly)

      Disconnect the F15 connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      F15-3 (+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
    OK
  2. INSPECT COMBINATION METER ASSEMBLY (OUTPUT VOLTAGE)


    1. Reconnect the F15 connector.

    2. A01NIW4E02
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Skid Control ECU)

      Disconnect the A90 connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A90-22 (SP1) - Body ground Power switch on (IG) 11 to 14 V

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


    1. A01NMMQE09
      Text in Illustration
      *1

      Component with harness connected

      (Combination Meter Assembly)

      Check the input waveform.


      1. Reconnect the A90 connector.

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

      3. Connect an oscilloscope to terminal F15-4 (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.


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


    1. Disconnect the F15 and A90 connectors.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A90-22 (SP1) - F15-4 (SI) Always Below 1 Ω
      A90-22 (SP1) - Body ground Always 10 kΩ or higher

    NG
    OK
  5. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - JUNCTION CONNECTOR)


    1. Disconnect the F93 connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      F15-3 (+S) - F93-57 Always Below 1 Ω
      F15-3 (+S) - Body ground Always 10 kΩ or higher

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


    1. Inspect for a short in the circuit that is connected to the 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.


      1. A01NJBKE04
        Text in Illustration
        *1

        Front view of wire harness connector

        (to Junction Connector)

        Disconnect the junction connector.

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

        Standard Voltage
        Tester Connection Condition Specified Condition
        F93-37 - Body ground Power switch on (IG) 4.5 to 14 V
        F93-27 - Body ground Power switch on (IG) 4.5 to 14 V
        F93-47 - Body ground Power switch on (IG) 4.5 to 14 V
        F93-77 - Body ground Power switch on (IG) 4.5 to 14 V
        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
      F93-37 - Body ground Entry and Start System A
      F93-27 - Body ground Separate Type Amplifier System B
      F93-47 - Body ground Audio and Visual System*1 or Navigation System*2 C
      F93-77 - Body ground Auto Wiper System*3 D

      • *1: w/o Navigation System

      • *2: w/ Navigation System

      • *3: w/ Auto Wiper System


    B
    C
    D
    A
  8. CHECK HARNESS AND CONNECTOR (POWER MANAGEMENT CONTROL ECU CIRCUIT)


    1. Disconnect the F97 connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      F97-14 (SPDI) - Body ground Always 10 kΩ or higher
      Result
      Result Proceed to
      OK (for LHD) A
      OK (for RHD) B
      NG C

    B
    C
    A
  9. CHECK HARNESS AND CONNECTOR (STEREO COMPONENT AMPLIFIER ASSEMBLY CIRCUIT)


    1. Disconnect the O42*1 or O33*2 connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      O42-17 (SPD)*1 - Body ground Always 10 kΩ or higher
      O33-11 (SPD)*2 - Body ground Always 10 kΩ or higher

      • *1: w/ Navigation System

      • *2: w/o Navigation System


    NG
    OK
  10. CHECK HARNESS AND CONNECTOR (RADIO RECEIVER ASSEMBLY CIRCUIT, MULTI-MEDIA MODULE RECEIVER ASSEMBLY CIRCUIT)


    1. Disconnect the G35*1, G37*2 or G9*3 connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      G35-56 (SPD)*1 - Body ground Always 10 kΩ or higher
      G37-17 (SPD)*2 - Body ground Always 10 kΩ or higher
      G9-3 (SPD)*3 - Body ground Always 10 kΩ or higher

      • *1: w/ Navigation System

      • *2: for Radio and Display Type

      • *3: for Radio Receiver Type

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

    B
    C
    A
  11. CHECK HARNESS AND CONNECTOR (WINDSHIELD WIPER SWITCH ASSEMBLY CIRCUIT)


    1. Disconnect the F42*1 or F81*2 connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      F42-6 (SPD)*1 - Body ground Always 10 kΩ or higher
      F81-4 (SPD)*2 - Body ground Always 10 kΩ or higher

      • *1: for LHD or for RHD Light Control Switch LH Side Type

      • *2: for RHD Light Control Switch RH Side Type


    NG
    OK