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On-Vehicle Inspection

  1. INSPECT 4WD CONTROL SWITCH 
    1. Check the harness and connector (ECU - battery and body ground).
      1. Measure the voltage and resistance according to the value(s) in the table below.

        Standard voltage 

        4WD CONTROL SWITCH TESTER CONNECTION AND SPECIFIED CONDITION VOLTAGE

        Tester Connection Condition Specified Condition
        A26-3 (IG) - Body ground Ignition switch ON 11 to 14 V

        If there is a malfunction, inspect the harness or connector. If the harness is malfunctioning, repair or replace harness or connector. If the harness or connector is normal, replace the 4WD control ECU (see REMOVAL  ).

        Standard resistance 

        4WD CONTROL SWITCH TESTER CONNECTION AND SPECIFIED CONDITION RESISTANCE

        Tester Connection Condition Specified Condition
        A26-4 (GND) - Body ground Always Below 1 Ω
        Fig 1: Inspecting 4WD Control Switch
        G05159072Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

        If there is a malfunction, repair or replace the harness or connector.

    2. Check the harness and connector (switch - ECU).
      1. Disconnect the A25 ECU connector.
      2. Disconnect the L1 switch connector.
      3. Measure the resistance according to the value(s) in the table below.
        Fig 2: Identifying A25 ECU Connector And L1 Switch Connector
        G05159091Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

        Standard resistance 

        A25 ECU CONNECTOR AND L1 SWITCH TESTER CONNECTION AND SPECIFIED CONDITION RESISTANCE

        Tester Connection Condition Specified Condition
        L1-2 (LO) - A25-13 (LO) Always Below 1 Ω
        L1-2 (LO) - Body ground Always 100 kΩ or higher
        L1-4 (GND) - Body ground Always Below 1 Ω
        L1-5 (2-4) - A25-11 (2-4) Always Below 1 Ω
        L1-5 (2-4) - Body ground Always 100 kΩ or higher

        If the resistance is not as specified, repair or replace the harness or connector.

    3. Check the 4WD control switch.
      1. Turn the ignition switch OFF.
      2. Connect the L1 switch connector.
      3. Connect the A25 and A26 ECU connectors.
      4. Measure the voltage according to the value(s) in the table below.

        Standard voltage 

        A25 ECU TESTER CONNECTION AND SPECIFIED CONDITION VOLTAGE

        Tester Connection Switch Condition Specified Condition
        A25-11 (2-4) - Body ground Ignition switch ON 4WD control switch 2WD position Below 1.5 V
        Ignition switch ON 4WD control switch 4H position Below 1.5 V
        Ignition switch ON 4WD control switch 4L position 10.5 to 14 V
        A25-13 (LO) - Body ground Ignition switch ON 4WD control switch 2WD position 10.5 to 14 V
        Ignition switch ON 4WD control switch 4H position Below 1.5 V
        Ignition switch ON 4WD control switch 4L position Below 1.5 V
        Fig 3: Identifying A25 ECU Connectors
        G05159073Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

        If the voltage is not as specified, check the 4WD control ECU.

    4. Check the 4WD control ECU.
      1. Disconnect the L1 switch connector.
      2. Measure the voltage according to the value(s) in the table below.

        Standard voltage 

        L1 SWITCH TESTER CONNECTION AND SPECIFIED CONDITION VOLTAGE

        Tester Connection Switch Condition Specified Condition
        L1-2 (LO) - Body ground Ignition switch ON 10.5 to 14 V
        L1-5 (2-4) - Body ground Ignition switch ON 10.5 to 14 V
        Fig 4: Identifying L1 Switch Connector
        G05159093Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

        If the voltage is not as specified, replace the 4WD control ECU (see REMOVAL  ). If the voltage is normal, replace the 4WD control switch.

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