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

A01MIF4E01

CAUTION / NOTICE / HINT

Note

When replacing the combination meter assembly, make sure to replace it with a new one.

PROCEDURE


  1. CHECK STEREO COMPONENT AMPLIFIER ASSEMBLY


    1. A01MI7CC73
      *a

      Rear view of wire harness connector

      (to Combination Meter Assembly)

      Disconnect the combination meter assembly connector.

    2. Disconnect the G105 radio and display assembly connector.

    3. Disconnect the G41 certification ECU (smart key ECU assembly) connector.

    4. Disconnect the G32 windshield wiper relay assembly connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      G13-19 (+S) - Body ground Power switch on (IG) 4.5 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - STEREO COMPONENT AMPLIFIER ASSEMBLY) Click here

    OK

  2. CHECK RADIO AND DISPLAY RECEIVER ASSEMBLY


    1. A01MI7CC73
      *a

      Rear view of wire harness connector

      (to Combination Meter Assembly)

      Disconnect the combination meter assembly connector.

    2. Disconnect the P49 stereo component amplifier assembly connector.

    3. Disconnect the G41 certification ECU (smart key ECU assembly) connector.

    4. Disconnect the G32 windshield wiper relay assembly connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      G13-19 (+S) - Body ground Power switch on (IG) 4.5 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - RADIO AND DISPLAY RECEIVER ASSEMBLY) Click here

    OK

  3. CHECK SMART KEY ECU ASSEMBLY


    1. A01MI7CC73
      *a

      Rear view of wire harness connector

      (to Combination Meter Assembly)

      Disconnect the combination meter assembly connector.

    2. Disconnect the P49 stereo component amplifier assembly connector.

    3. Disconnect the G105 radio and display receiver assembly connector.

    4. Disconnect the G32 windshield wiper relay assembly connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      G13-19 (+S) - Body ground Power switch on (IG) 4.5 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - CERTIFICATION ECU [SMART KEY ECU ASSEMBLY]) Click here

    OK

  4. CHECK WINDSHIELD WIPER RELAY ASSEMBLY


    1. A01MI7CC73
      *a

      Rear view of wire harness connector

      (to Combination Meter Assembly)

      Disconnect the combination meter assembly connector.

    2. Disconnect the P49 stereo component amplifier assembly connector.

    3. Disconnect the G105 radio and display receiver assembly connector.

    4. Disconnect the G41 certification ECU (smart key ECU assembly) connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      G13-19 (+S) - Body ground Power switch on (IG) 4.5 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - WINDSHIELD WIPER RELAY ASSEMBLY) Click here

    OK

  5. CHECK COMBINATION METER ASSEMBLY (OUTPUT VOLTAGE)


    1. A01MGDLC05
      *a

      Front view of wire harness connector

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

      Disconnect the brake booster with master cylinder assembly (skid control ECU) connector.

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      A57-11 (SP1) - Body ground Power switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG

    CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY [SKID CONTROL ECU]) Click here

    OK

  6. CHECK COMBINATION METER ASSEMBLY (INPUT WAVEFORM)


    1. A01MJFEC14
      *a

      Component with harness connected

      (Combination Meter Assembly)
      *b Waveform

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

    2. Connect an oscilloscope to terminal G13-20 (SI) and the body ground.

    3. Check the signal waveform according to the condition(s) in the table below.

      Measurement Condition
      Item Condition
      Tester Connection G13-20 (SI) - Body ground
      Tool Setting 5 V/DIV., 20 ms./DIV.
      Vehicle Condition Driving at approximately 20 km/h (12 mph)

      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.

      OK
      The waveform displayed is as shown in the illustration.
      Result
      Result Proceed to
      OK A
      NG (for LHD) B
      NG (for RHD) C

    A

    REPLACE COMBINATION METER ASSEMBLY Click here

    B

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SKID CONTROL ECU) Click here

    C

    REPLACE BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY (SKID CONTROL ECU) Click here

  7. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - STEREO COMPONENT AMPLIFIER ASSEMBLY)


    1. Disconnect the G13 combination meter assembly connector.

    2. Disconnect the P49 stereo component amplifier assembly connector.

    3. Disconnect the G105 radio and display receiver assembly connector.

    4. Disconnect the G41 certification ECU (smart key ECU assembly) connector.

    5. Disconnect the G32 windshield wiper relay assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      G13-19 (+S) - P49-11 (SPD) Always Below 1 Ω
      G13-19 (+S) or P49-11 (SPD) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE STEREO COMPONENT AMPLIFIER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  8. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - RADIO AND DISPLAY RECEIVER ASSEMBLY)


    1. Disconnect the G13 combination meter assembly connector.

    2. Disconnect the P49 stereo component amplifier assembly connector.

    3. Disconnect the G105 radio and display receiver assembly connector.

    4. Disconnect the G41 certification ECU (smart key ECU assembly) connector.

    5. Disconnect the G32 windshield wiper relay assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      G13-19 (+S) - G105-56 (SPD) Always Below 1 Ω
      G13-19 (+S) or G105-56 (SPD) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE RADIO AND DISPLAY RECEIVER ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  9. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - CERTIFICATION ECU [SMART KEY ECU ASSEMBLY])


    1. Disconnect the G13 combination meter assembly connector.

    2. Disconnect the P49 stereo component amplifier assembly connector.

    3. Disconnect the G105 radio and display receiver assembly connector.

    4. Disconnect the G41 certification ECU (smart key ECU assembly) connector.

    5. Disconnect the G32 windshield wiper relay assembly connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      G13-19 (+S) - G41-5 (SPD) Always Below 1 Ω
      G13-19 (+S) or G41-5 (SPD) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE SMART KEY ECU ASSEMBLY

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  10. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - WINDSHIELD WIPER RELAY ASSEMBLY)


    1. Disconnect the G13 combination meter assembly connector.

    2. Disconnect the 49 stereo component amplifier assembly connector.

    3. Disconnect the G105 radio and display receiver assembly connector.

    4. Disconnect the G41 certification ECU (smart key ECU assembly) connector.

    5. Disconnect the G32 windshield wiper relay assembly connector.*3

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      G13-19 (+S) - G32-6 (SPD) Always Below 1 Ω
      G13-19 (+S) or G32-6 (SPD) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK

    REPLACE WINDSHIELD WIPER RELAY ASSEMBLY Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  11. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - BRAKE BOOSTER WITH MASTER CYLINDER ASSEMBLY [SKID CONTROL ECU])


    1. Disconnect the G13 combination meter assembly connector.

    2. Disconnect the A56 brake booster with master cylinder 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
      G13-20 (SI) - A56-11 (SP1) Always Below 1 Ω
      G13-20 (SI) or A56-11 (SP1) - 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