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Home >> Infiniti >> 2017 >> QX70 RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 227 (Audio, Visual & Navigation System (Telematics System) (DTC/Circuit Diagnosis) (Hybrid)) >> DTC / Circuit Diagnosis >> Power Supply And Ground Circuit >> TCU >> Diagnosis Procedure

Diagnosis Procedure

WARNING: This page is about a different car, the 2016 Infiniti Q50. However, it is still accessible from the selected car via links, so may be relevant.

  1. CHECK FUSE

    Check if the fuse is burned out.

    Power source Fuse No.
    Battery #7
    Ignition switch ACC or ON #1

    Is the inspection result normal?

    YES 

    GO TO STEP 2. 

    NO 

    Replace the fuse after repairing the applicable circuit.

  2. CHECK BATTERY POWER SUPPLY

    Check the voltage between the TCU harness connector and ground.

    (+) (-) Condition Reference value
    (Approx.)
    TCU
    Connector Terminal
    M159 1 Ground Ignition switch OFF Battery Voltage

    Is the inspection result normal?

    YES 

    GO TO STEP 3. 

    NO 

    Repair or replace harness between TCU and fuse.

  3. CHECK ACC POWER SUPPLY

    Check the voltage between the TCU harness connector and ground.

    (+) (-) Condition Reference value
    (Approx.)
    TCU
    Connector Terminal
    M159 2 Ground Ignition switch ACC 12.0 V

    Is the inspection result normal?

    YES 

    GO TO STEP 4. 

    NO 

    Repair or replace harness between TCU and fuse.

  4. CHECK GROUND CIRCUIT

    1. Turn ignition switch OFF.
    2. Disconnect TCU harness connector.
    3. Check the continuity between TCU harness connector and ground.
      TCU Ground Continuity
      Connector Terminal
      M159 28
      29 Existed

    Is the inspection result normal?

    YES 

    INSPECTION END

    NO 

    Repair or replace TCU ground circuit.