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Home >> Lexus >> 2005 >> LS 430 >> Repair and Diagnosis >> Electrical >> Gauges >> Combination Meter - Diagnostics >> Malfunction In Tachometer >> Inspection Procedure

Inspection Procedure

  1. PERFORM ACTIVE TEST BY HAND-HELD TESTER 
    1. Operate the hand-held tester according to the steps on the display and select the "ACTIVE TEST".

    METER: 

    TACHO METER ACTIVE TEST REFERENCE

    Item Test Details Diagnostic Note
    TACHOMETER Orpm / 1000rpm / 2000rpm / 3000rpm / 4000rpm / 5000rpm / 6000rpm / 7000rpm -

    OK: 

    Needle indication is normal. 

    NG: REPLACE COMBINATION METER ASSY (SEE  OVERHAUL  ) 

    OK: GO TO NEXT STEP 

  2. READ VALUE OF HAND-HELD TESTER (ENGINE SPEED SIGNAL) 
    1. Operate the hand-held tester according to the steps on the display and select the "DATA LIST".

    METER: 

    TACHO METER DATA LIST REFERENCE

    Item Measurement Item/ Range (Display) Normal Condition Diagnostic Note
    TACHO METER Engine speed / Min.: 50 rpm, Max.: 12,750 rpm Almost same as actual engine speed (When engine is running) -

    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 ASSY (SEE  OVERHAUL  ) 

  3. READ VALUE OF HAND-HELD TESTER (ENGINE SPEED SIGNAL) 
    1. Operate the hand-held tester according to the steps on the display and select the "DATA LIST".

    ENGINE: 

    DATA LIST REFERENCE

    Item Measurement Item/ Range (Display) Normal Condition Diagnostic Note
    ENGINE SPD Engine speed / Min.: 50 rpm, Max.: 12,750 rpm Almost same as actual engine speed (When engine is running) -

    OK: 

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

    NG: GO TO ENGINE CONTROL SYSTEM (SEE  REPLACEMENT  ) 

    OK: GO TO NEXT STEP 

  4. INSPECT COMBINATION METER ASSY 

    INSPECTION USING OSCILLOSCOPE 

    1. Check the input signal waveform.
    1. Remove the combination meter assy.
    2. Connect the oscilloscope to the terminals C12-4 and body ground.
    3. Start the engine.
    4. Check the signal waveform according to the condition (s) in the table below.
    SIGNAL WAVEFORM CONDITION

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

    OK: 

    As shown in the illustration 

    Fig 1: Identifying Terminals C12-4
    G03000687Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    Fig 2: Identifying Signal Waveform
    G03000688Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: Go to step 5 

    OK: REPLACE COMBINATION METER ASSY (SEE  OVERHAUL  ) 

  5. CHECK HARNESS AND CONNECTOR (ECM - COMBINATION METER ASSY) (SEE  HOW TO PROCEED WITH TROUBLESHOOTING  ) 
    1. Disconnect the C12 and E2 connectors.
    2. Measure the resistance according to the value (s) in the table below.

    Standard 

    C12 AND E2 CONNECTORS RESISTANCE SPECIFICATIONS

    Tester Connection Condition Specified Condition
    C12-4 - E2-16 Always Below 1 Ω
    C12-4 - Body ground Always 10 kΩ or higher
    Fig 3: Identifying C12 And E2 Connectors
    G03000689Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS AND CONNECTOR 

    OK: GO TO NEXT STEP 

  6. INSPECT COMBINATION METER ASSY 
    1. Disconnect the E2 connector.
    2. Measure the voltage according to the value (s) in the table below.

    Standard 

    E2 CONNECTOR VOLTAGE SPECIFICATIONS

    Tester Connection Condition Specified Condition
    E2-16 - Body ground Ignition switch ON 10 to 14 V

    NG: REPLACE COMBINATION METER ASSY (SEE  OVERHAUL  ) 

    Fig 4: Identifying E2 Connector
    G03000690Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: GO TO ENGINE CONTROL SYSTEM (SEE  REPLACEMENT  ) 

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