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Speed Signal Circuit: Procedure

  1. INSPECT COMBINATION METER ASSEMBLY (OUTPUT WAVEFORM) 
    1. Remove the combination meter assembly, but do not disconnect the connector.
      Fig 1: Identifying Combination Meter Assembly Connector Terminals
      GTY157397Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Connect an oscilloscope to terminal F1-17 (+S) and the body ground.
    3. Shift the transmission gear selector lever to the neutral position.
    4. Jack up the vehicle.
    5. Turn the ignition switch to ON.
    6. Turn the wheel slowly.
    7. Check the signal waveform according to the condition in the table below.
      Item Condition
      Tester Range 5V/DIV., 20 msec/DIV.
      Vehicle Condition Driving at approximately 20 km/h (12 mph)

      OK

      The waveform is displayed as shown in the illustration.

      HINT: 

      As the vehicle speed increases, the cycle of the waveform narrows.

    NG → See step   2 

    OK → RETURN TO THE ORIGINAL INSPECTION FOR OTHER SYSTEM 

  2. INSPECT COMBINATION METER ASSEMBLY (INPUT VOLTAGE) 
    1. Disconnect the F1 combination meter assembly connector.
      Fig 2: Identifying F1 Combination Meter Assembly Connector Terminals
      GTY158708Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the voltage according to the value in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      F1-17 (+S) - Body ground Ignition switch ON 4.5 to 14 V

      HINT: 

      If any of the ECUs specified in the wiring diagram supplied power to the combination meter, the combination meter will output a waveform.

    3. Reconnect the combination meter assembly connector.

    NG → See step   5 

    OK: Go to next step 

  3. INSPECT COMBINATION METER ASSEMBLY (OUTPUT VOLTAGE) 
    1. Disconnect the A15 ABS and traction actuator (skid control ECU) connector.
      Fig 3: Wire Harness Connector To ABS And Traction Actuator (Skid Control ECU)
      GTY165085Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Measure the voltage according to the value(s) in the table below.

      Standard Voltage

      Tester Connection Switch Condition Specified Condition
      A15-11 (SP1) - Body ground Ignition switch ON 11 to 14 V
    3. Reconnect the ABS and traction actuator (skid control ECU) connector.

    NG → See step   8 

    OK: Go to next step 

  4. INSPECT COMBINATION METER ASSEMBLY (INPUT WAVEFORM) 
    1. Reconnect the A15 ABS and traction actuator (skid control ECU) connector.
      Fig 4: Identifying Combination Meter Assembly Connector Terminals
      GTY157398Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Remove the combination meter assembly, but do not disconnected the connector.
    3. Connect an oscilloscope to terminal F1-18 (SI) and the body ground.
    4. Shift the transmission gear selector lever to the neutral position.
    5. Jack up the vehicle.
    6. Turn the ignition switch to ON.
    7. Turn the wheel slowly.
    8. Check the signal waveform according to the condition in the table below.
      Item Condition
      Tester Range 5V/DIV., 20 msec/DIV.
      Vehicle Condition Driving at approximately 20 km/h (12 mph)

      OK

      The waveform is displayed as shown in the illustration.

      HINT: 

      As the vehicle speed increases, the cycle of the waveform narrows.

    NG → See step   10 

    OK → See step   9 

  5. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - MAIN BODY ECU) 
    1. Disconnect the 4C main body ECU connector.
      Fig 5: Identifying F1 Combination Meter Assembly Connector Terminals
      GTY157394Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the F1 combination meter asembly connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      F1-17 (+S) - 4C-8 Always Below 1 Ω
      F1-17 (+S) or 4C-8 - Body ground Always 10 kΩ or higher
    4. Reconnect the main body ECU connector.
    5. Reconnect the combination meter assembly connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  6. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - MALFUNCTIONING ECU) 
    Fig 6: Identifying Combination Meter Assembly Malfunctioning ECU Connectors Terminals
    GTY157395Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    1. Disconnect the F1 combination meter assembly connector.
    2. Disconnect the A21 ECM connector, F12 radio receiver connector or F26 tire pressure warning ECU connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      F1-17 (+S) - A21-8 (SPD) Always Below 1 Ω
      F1-17 (+S) - F12-3 (SPD) Always Below 1 Ω
      F1-17 (+S) - F26-2 (SPD) Always Below 1 Ω
      F1-17 (+S) or A21-8 (SPD) - Body ground Always 10 kΩ or higher
      F1-17 (+S) or F12-3 (SPD) - Body ground Always 10 kΩ or higher
      F1-17 (+S) or F26-2 (SPD) - Body ground Always 10 kΩ or higher
    4. Reconnect the combination meter assembly connector.
    5. Reconnect the ECM connector, the radio receiver connector or the tire pressure warning ECU connector.

    NG → See step   7 

    OK → REPLACE MALFUNCTIONING ECU 

  7. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU - MALFUNCTIONING ECU) 
    1. Disconnect the 4B, 4C or 4D main body ECU connector(s).
      Fig 7: Identifying Main Body ECU - Malfunctioning ECU Connectors Terminals
      GTY157396Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the A21 ECM connector, the F12 radio receiver connector or F26 tire pressure warning ECU connector.
    3. Measure the resistance according to the values in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      A21-8 (SPD) - 4B-26 Always Below 1 Ω
      F12-3 (SPD) - 4D-8 Always Below 1 Ω
      F26-2 (SPD) - 4D-8 Always Below 1 Ω
      A21-8 (SPD) or 4B-26 - Body ground Always 10 kΩ or higher
      F12-3 (SPD) or 4D-8 - Body ground Always 10 kΩ or higher
      F26-2 (SPD) or 4D-8 - Body ground Always 10 kΩ or higher
    4. Reconnect the main body ECU connector.
    5. Reconnect the ECM connector, the radio receiver connector or the tire pressure warning ECU connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK → REPLACE MAIN BODY ECU 

  8. CHECK HARNESS AND CONNECTOR (COMBINATION METER ASSEMBLY - SKID CONTROL ECU) 
    1. Disconnect the F1 combination meter assembly connector.
      Fig 8: Wire Harness Connectors Combination Meter To ABS And Traction Actuator (Skid Control ECU)
      GTY165555Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    2. Disconnect the A15 ABS and traction actuator (skid control ECU) connector.
    3. Measure the resistance according to the values in the table below.

      Standard Resistance

      Tester Connection Condition Specified Condition
      F1-18 (SI) - A15-11 (SP1) Always Below 1 Ω
      F1-18 (SI) or A15-11 (SP1) - Body ground Always 10 kΩ or higher
    4. Reconnect the combination meter assembly connector.
    5. Reconnect the ABS and traction actuator (skid control ECU) connector.

    NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK → See step   11 

  9. REPLACE COMBINATION METER ASSEMBLY. Refer to  REMOVAL 
  10. REPLACE ABS AND TRACTION ACTUATOR (SKID CONTROL ECU). Refer to  REMOVAL 
  11. REPLACE COMBINATION METER ASSEMBLY. Refer to  REMOVAL 
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