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Home >> Toyota >> 2009 >> Matrix Base, Standard >> Repair and Diagnosis >> Accessories & Equipment >> Warning Systems >> Tire Pressure Monitoring >> Tire Pressure Warning System >> DTC C2194/94: Engine Speed Signal Error (Test Mode DTC) >> Inspection Procedure
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Inspection Procedure

NOTE:
  • When replacing the tire pressure warning ECU, read the transmitter IDs stored in the old ECU using the Techstream and write them down before removal.
  • It is necessary to perform initialization (See INITIALIZATION ) after registration (See REGISTRATION ) of the transmitter IDs into the tire pressure warning ECU if the ECU has been replaced.
  1. READ VALUE USING TECHSTREAM (ENGINE SPEED) 
    1. Turn the ignition switch off.
    2. Connect the Techstream to the DLC3.
    3. Turn the ignition switch to ON.
    4. Turn the Techstream on.
    5. Enter the following menus: Chassis / Tire Pressure Monitor / Data List.
    6. Check that the values indicated on the Techstream and on the combination meter are the same.

    Tire Pressure Monitor 

    DATA LIST REFERENCE

    Tester Display Measurement Item/Range Normal Condition Diagnostic Note
    Engine Speed Engine speed/
    min.: 0 rpm
    max.: 65535 rpm    		 Almost same as actual engine speed Speed indicated on combination meter

    OK: 

    Engine speed indicated on the Techstream and on the combination meter are the same  .

    NG: Go to step   2 

    OK: USE SIMULATION METHOD TO CHECK  (See PROBLEM SYMPTOMS TABLE )

  2. INSPECT TIRE PRESSURE WARNING ECU (TACH SIGNAL) 
    1. Disconnect the E44 ECU connector.
    2. Start the engine.
    3. Check the waveform of the ECU connector using an oscilloscope while idling the engine.

    OK 

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Condition Specified Condition
    E44-4 (TACH) - E44-9 (GND) Idling Correct waveform appears as shown

    Tool Setting 

    TOOL SETTING REFERENCE

    Item Contents
    Tool Setting 5V/DIV., 10 ms/DIV.
    Fig 1: Identifying Terminals Of E44 ECU Connector And Waveform
    G06034811Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    HINT:

    The wavelength becomes shorter as the engine speed increases.

    NG: Go to step   3 

    OK: REPLACE TIRE PRESSURE WARNING ECU  (See TIRE PRESSURE WARNING ECU )

  3. CHECK HARNESS AND CONNECTOR (TIRE PRESSURE WARNING ECU - ECM) 
    1. Disconnect the E44 ECU connector.
    2. Disconnect the A37 ECM connector.
    3. Measure the resistance according to the value (s) in the table below.

    Standard Resistance 

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Condition Specified Condition
    E44-4 (TACH) - A37-15 (TACH) Always Below 1 Ω
    E44-4 (TACH) - Body ground Always 10 kΩ or higher

    Result 

    RESULT REFERENCE

    Result Proceed to
    OK (for 2ZR-FE) A
    OK (for 2AZ-FE) B
    NG C
    Fig 2: Identifying Terminals Of E44 ECU And A37 ECM Connectors
    G06034812Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    B: REPLACE ECM (for 2ZR-FE)  (See REMOVAL )

    C: REPLACE ECM (for 2AZ-FE)  (See REMOVAL )

    A: REPAIR OR REPLACE HARNESS OR CONNECTOR 

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