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Inspection Procedure

NOTE: When using the Techstream with the engine switch off to troubleshoot:
Connect the Techstream to the vehicle, and turn a courtesy switch on and off at 1.5 second intervals until communication between the Techstream and vehicle begins.
  1. CLEAR DTC 
    1. Clear the DTC (See DTC CHECK / CLEAR ).
  2. CHECK FOR DTC 
    1. Recheck for DTCs (See DTC CHECK / CLEAR ).

    Result 

    RESULT CHART

    Result Proceed to
    DTC B1478 is output A
    DTC B1478 is not output B

    B: USE SIMULATION METHOD TO CHECK  (See ELECTRONIC CIRCUIT INSPECTION PROCEDURE )

    A: Go to next Step 

  3. CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - SEAT CLIMATE CONTROL ECU) 
    1. Disconnect the E36 amplifier connector.
    2. Disconnect the c24 and c38 ECU connectors.
    3. Measure the resistance and voltage according to the value (s) in the tables below.

    Standard Resistance 

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Condition Specified Condition
    E36-28 (LIN2) - c24-13 (LIN) Always Below 1 Ω
    E36-28 (LIN2) - c38-13 (LIN) Always Below 1 Ω
    E36-28 (LIN2) - Body ground Always 10 kΩ or higher

    Standard Voltage 

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Condition Specified Condition
    E36-28 (LIN2) - Body ground Always Below 1 V

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    Fig 1: Checking Harness And Connector (Air Conditioning Amplifier - Seat Climate Control ECU)
    G05764903Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    OK: Go to next Step 

  4. CHECK HARNESS AND CONNECTOR (SEAT CLIMATE CONTROL ECU - BATTERY AND BODY GROUND) 
    1. Disconnect the c24 and c38 ECU connectors.
    2. Measure the resistance and voltage according to the value (s) in the tables below.

    Standard Resistance 

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Condition Specified Condition
    C24-12 (GND) - Body ground Always Below 1 Ω
    C38-12 (GND) - Body ground Always Below 1 Ω
    Fig 2: Checking Harness And Connector (Seat Climate Control ECU - Battery And Body Ground)
    G05764904Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    Standard Voltage 

    TESTER CONNECTION SPECIFIED CONDITION CHART

    Tester Connection Condition Specified Condition
    c24-2 (B) - Body ground Always 11 to 14 V
    c38-2 (B) - Body ground Always 11 to 14 V

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next Step 

  5. CHECK SEAT CLIMATE CONTROL ECU LH 
    1. Temporarily replace the seat climate control ECU LH with a new or normally functioning one (See DISASSEMBLY ).
    2. Check that the driver side seat climate control function is normal.

    OK: Driver side seat climate control function is normal. 

    NG:  Go to step  6

    OK: END (SEAT CLIMATE CONTROL ECU LH IS DEFECTIVE) 

  6. CHECK SEAT CLIMATE CONTROL ECU RH 
    1. Temporarily replace the seat climate control ECU RH with a new or normally functioning one (See DISASSEMBLY ).
    2. Check that the driver side seat climate control function is normal.

    OK: Front passenger side seat climate control function is normal. 

    NG: REPLACE AIR CONDITIONING AMPLIFIER  (See REMOVAL )

    OK: END (SEAT CLIMATE CONTROL ECU RH IS DEFECTIVE) 

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