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Home >> Lexus >> 2008 >> GS 460 >> Repair and Diagnosis >> Accessories & Equipment >> Gauges & Instrument Panels >> Meter >> Meter / Gauge System >> Tachometer Malfunction >> Inspection Procedure

Inspection Procedure

  1. PERFORM ACTIVE TEST USING TECHSTREAM (TACHO METER OPERATION) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the tester ON.
    4. Enter the following menus: Body Electrical / Combination Meter / Active Test.
    5. Check the operation by referring to the values in the table below.

      Combination Meter: 

      TESTER DISPLAY REFERENCE CHART

      Tester Display Test Part Control Range Diagnostic Note
      Tacho Meter Operation Tachometer 0, 1000, 2000, 3000, 4000, 5000, 6000, 7000 (rpm) -

      OK: 

      Needle indication is normal. 

    NG : REPLACE COMBINATION METER 

    OK : Go to next step 

  2. READ VALUE USING TECHSTREAM (ENGINE RPM) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the tester ON.
    4. Enter the following menus: Body Electrical / Combination Meter / Data List.
    5. Check the values by referring to the values in the table below.

      Combination Meter: 

      TESTER DISPLAY REFERENCE CHART

      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Engine Rpm Engine speed/Min.: 0 rpm, Max.: 12750 rpm Almost same as actual engine speed (When engine is running) If data received from the ECM exceeds the range that can be displayed on the meter, the meter continues to display the maximum value of the range.

      OK: 

      Engine speed displayed on the tester is almost the same as the actual engine speed. 

    NG : Go to step 3 

    OK : REPLACE COMBINATION METER 

  3. READ VALUE USING TECHSTREAM (ENGINE SPEED) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the tester ON.
    4. Enter the following menus: Powertrain / Engine and ECT / Data List.
    5. Check the values by referring to the table below.

      Engine and ECT: 

      TESTER DISPLAY REFERENCE CHART

      Tester Display Measurement Item/Range Normal Condition Diagnostic Note
      Engine Speed Engine speed/Min.: 0 rpm, Max.: 16383.75 rpm Almost same as actual engine speed (When engine is running) -

    NG :  GO TO ENGINE CONTROL SYSTEM

    OK : Go to next step 

  4. CHECK COMBINATION METER 
    1. Check the input signal waveform.
      1. Remove the combination meter with connector still connected.
      2. Connect the oscilloscope to terminal K31 - 27 and body ground.
      3. Start the engine.
        Fig 1: Checking Combination Meter
        G05299343Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      4. Check the signal waveform of the connector.
        ITEM CONDITION REFERENCE CHART

        Item Condition
        Tool setting 5 V/DIV., 10 ms/DIV.
        Vehicle condition Engine idle speed

        OK: 

        As shown in the illustration 

    OK : REPLACE COMBINATION METER 

    Fig 2: Identifying Signal Waveform
    G05140985Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG : Go to next step 

  5. CHECK HARNESS AND CONNECTOR (BETWEEN COMBINATION METER AND ECM) 
    1. Disconnect the A6 ECM connector.
    2. Disconnect the A7 ECM connector.
    3. Disconnect the K31 meter connector.
      Fig 3: Checking Harness And Connector (Between Combination Meter And ECM)
      G05807501Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    4. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      STANDARD RESISTANCE

      Tester Connection Condition Specified Condition
      K31-27 - A7-16(1) Always Below 1 Ω
      K31-27 - A6-15(2) Always Below 1 Ω
      K31-27 - Body ground Always 10 kΩ or higher
      (1) 2GR-FSE
      (2) 1UR-FSE

    NG : REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK : REPLACE ECM 

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