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*a. 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 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

A01G3VOE01

PROCEDURE


  1. INSPECT ECU TERMINAL VOLTAGE (INPUT VOLTAGE)


    1. A01G3CVC06
      *a

      Front view of wire harness connector

      (to Combination Meter Assembly)

      Disconnect the E46 combination meter assembly connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      E46-6 (+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
    OK
  2. INSPECT COMBINATION METER ASSEMBLY (OUTPUT VOLTAGE)


    1. Reconnect the E46 combination meter assembly connector.

    2. A01G3S0C53
      *a

      Front view of wire harness connector

      (to Brake Booster with Master Cylinder Assembly (Skid Control ECU))

      Disconnect the A144 skid control ECU connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A144-11 (SP1) - Body ground Power switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

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


    1. A01G3B2C01
      *a

      Component with harness connected

      (Combination Meter Assembly)

      Check the input waveform.


      1. Reconnect the A144 skid control ECU connector.

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

      3. Connect an oscilloscope to terminal E46-5 (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
    NG
  4. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - SKID CONTROL ECU)


    1. Disconnect the E46 combination meter assembly connector.

    2. Disconnect the A144 skid control ECU connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      E46-5 (SI) - A144-11 (SP1) Always Below 1 Ω
      E46-5 (SI) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

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


    1. Disconnect the 3D instrument panel junction block assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      E46-6 (+S) - 3D-38 Always Below 1 Ω
      E46-6 (+S) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG
    OK
  6. CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY)


    1. Inspect for a short in the wire harness and connectors connected to the instrument panel junction block assembly 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. A01G2MVC01
        *a

        Component without harness connected

        (Instrument Panel Junction Block Assembly)

        Disconnect the 3D instrument panel junction block assembly connector.

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

        Standard Voltage
        Tester Connection Condition Specified Condition
        3D-19 - Body ground Power switch on (IG) 4.5 to 14 V
        3D-20 - 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 of 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
      3D-19 - Body ground Audio and visual system*3 or Navigation system*4 A
      3D-20 - Body ground*1 Entry and smart system B
      3D-20 - Body ground*2 Entry and smart system, Audio and visual system*5 or Auto wiper system*6 C

      • *1: for 6 speakers and w/o Auto wiper system

      • *2: for 9 speakers or w/ Auto wiper system

      • *3: w/o Navigation system

      • *4: w/ Navigation system

      • *5: for 9 speakers

      • *6: w/ Auto wiper system


    B
    C
    A
  8. CHECK HARNESS AND CONNECTOR (RADIO AND DISPLAY RECEIVER ASSEMBLY CIRCUIT)


    1. Disconnect the E60 radio and display receiver assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      E60-17 (SPD) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK
    NG
  9. CHECK HARNESS AND CONNECTOR (INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY - NO. 7 JUNCTION CONNECTOR)


    1. Disconnect the E54 No. 7 junction connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      3D-20 - E54-7 Always Below 1 Ω
      3D-20 - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG
    OK
  10. CHECK HARNESS AND CONNECTOR (NO. 7 JUNCTION CONNECTOR)


    1. Inspect for a short in the wire harness and connectors connected to the No. 7 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. Measure the voltage according to the value(s) in the table below.

        Standard Voltage
        Tester Connection Condition Specified Condition
        E54-8 - Body ground Power switch on (IG) 4.5 to 14 V
        E54-10 - Body ground Power switch on (IG) 4.5 to 14 V
        E54-11 - 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 of the circuits. B

    B
    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
      E54-8 - Body ground Auto wiper system*1 A
      E54-10 - Body ground Entry and start system B
      E54-11 - Body ground Audio and visual system*2 C

      • *1: w/ Auto wiper system

      • *2: for 9 speakers


    B
    C
    A
  12. CHECK HARNESS AND CONNECTOR (WINDSHIELD WIPER RELAY ASSEMBLY CIRCUIT)


    1. Disconnect the E95 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
      E95-24 (SPD) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK
    NG
  13. CHECK HARNESS AND CONNECTOR (POWER MANAGEMENT CONTROL ECU CIRCUIT)


    1. Disconnect the E111 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
      E111-14 (SPDI) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

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


    1. Disconnect the E92 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
      E92-11 (SPD) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK
    NG