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

A003UYAE01

INSPECTION PROCEDURE

PROCEDURE


  1. INSPECT ECU TERMINAL VOLTAGE (INPUT VOLTAGE)


    1. A003RK8E72
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Combination Meter Assembly)

      Disconnect the E46 connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      E46-36 (+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

    CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - NO. 4 JUNCTION BLOCK) Click here

    OK

  2. INSPECT COMBINATION METER ASSEMBLY (OUTPUT VOLTAGE)


    1. Reconnect the E46 connector.

    2. A003UTKE47
      Text in Illustration
      *1

      Front view of wire harness connector

      (to Skid Control ECU)

      Disconnect the A104 connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A104-11 (SP1) - Body ground Power switch on (IG) 11 to 14 V

    NG

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

    OK

  3. INSPECT SKID CONTROL ECU (INPUT WAVEFORM)


    1. A003T12E53
      Text in Illustration
      *1

      Component with harness connected

      (Combination Meter Assembly)

      Check the input waveform.


      1. Reconnect the A104 connector.

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

      3. Connect an oscilloscope to terminal E46-35 (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 Wheel being rotated
        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.

        Result
        Result Proceed to
        OK A
        NG (for LHD) B
        NG (for RHD) C

    B

    REPLACE SKID CONTROL ECU Click here

    C

    REPLACE SKID CONTROL ECU Click here

    A

    REPLACE COMBINATION METER ASSEMBLY Click here

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


    1. Disconnect the E46 and A104 connectors.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A104-11 (SP1) - E46-35 (SI) Always Below 1 Ω
      A104-11 (SP1) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE COMBINATION METER ASSEMBLY Click here

  5. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - NO. 4 JUNCTION BLOCK)


    1. Disconnect the 4B connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      E46-36 (+S) - 4B-8 Always Below 1 Ω
      E46-36 (+S) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  6. CHECK HARNESS AND CONNECTOR (NO. 4 JUNCTION BLOCK)


    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 4A connector.

        A003TWIE03

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

        Standard Voltage
        Tester Connection Condition Specified Condition
        4A-8 - Body ground Power switch on (IG) 4.5 to 14 V
        4A-20 - Body ground Power switch on (IG) 4.5 to 14 V
        4A-21 - Body ground Power switch on (IG) 4.5 to 14 V
        4B-20 - Body ground Power switch on (IG) 4.5 to 14 V
        Text in Illustration
        *1

        Front view of wire harness connector

        (to No. 4 Junction Block)
        Result
        Result Proceed to
        Voltage is not present in one circuit. A
        Voltage is present in all the circuits. B

    B

    REPLACE NO. 4 JUNCTION BLOCK

    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
      4B-20 - Body ground Entry and Start System A
      4A-8*1 - Body ground Wiper and Washer System B
      4A-20*2 - Body ground Audio and Visual System C
      4A-20*3 - Body ground Navigation System C
      4A-21*4 - Body ground Lighting System D

      • *1: w/ Auto Wiper System

      • *2: w/ Radio Receiver

      • *3: w/ Navigation System

      • *4: w/ Automatic Type Headlight Beam Level Control


    B

    CHECK HARNESS AND CONNECTOR (WINDSHIELD WIPER RELAY ASSEMBLY CIRCUIT) Click here

    C

    CHECK HARNESS AND CONNECTOR (RADIO RECEIVER CIRCUIT, NAVIGATION RECEIVER ASSEMBLY CIRCUIT) Click here

    D

    CHECK HARNESS AND CONNECTOR (HEADLIGHT LEVELING ECU ASSEMBLY CIRCUIT) Click here

    A

  8. CHECK HARNESS AND CONNECTOR (POWER MANAGEMENT CONTROL ECU CIRCUIT)


    1. Disconnect the E111 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

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE POWER MANAGEMENT CONTROL ECU Click here

  9. CHECK HARNESS AND CONNECTOR (WINDSHIELD WIPER RELAY ASSEMBLY CIRCUIT)


    1. Disconnect the E40 connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      E40-19 (SPD) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE WINDSHIELD WIPER RELAY ASSEMBLY Click here

  10. CHECK HARNESS AND CONNECTOR (RADIO RECEIVER CIRCUIT, NAVIGATION RECEIVER ASSEMBLY CIRCUIT)


    1. Disconnect the E26*1 or E35*2 connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      E26-3 (SPD)*1 - Body ground Always 10 kΩ or higher
      E35-3 (SPD)*2 - Body ground Always 10 kΩ or higher

      • *1: w/ Radio Receiver

      • *2: w/ Navigation System


    B

    REPLACE NAVIGATION RECEIVER ASSEMBLY Click here

    C

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    A

    REPLACE RADIO RECEIVER ASSEMBLY Click here

  11. CHECK HARNESS AND CONNECTOR (HEADLIGHT LEVELING ECU ASSEMBLY CIRCUIT)


    1. Disconnect the A35 connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      A35-16 (SPDR) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE HEADLIGHT LEVELING ECU ASSEMBLY Click here