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Home >> Infiniti >> 2017 >> QX70 RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 183 (LAN System (Can) (Wiring Diagrams And Circuit Diagnosis) (Hybrid)) >> Circuit Diagnosis >> TCU Branch Line Circuit >> 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 CONNECTOR

    1. Turn the ignition switch OFF.
    2. Disconnect the battery cable from the negative terminal.
    3. Check the terminals and connectors of the TCU for damage, bend and loose connection (unit side and connector side).

    Is the inspection result normal?

    YES 

    GO TO STEP 2  .

    NO 

    Repair the terminal and connector.

  2. CHECK HARNESS FOR OPEN CIRCUIT

    1. Disconnect the connector of TCU.
    2. Check the resistance between the TCU harness connector terminals.
      TCU harness connector Resistance (Ω)
      Connector No. Terminal No.
      M159 6 7 Approx. 54 - 66

    Is the measurement value within the specification?

    YES 

    GO TO STEP 3  .

    NO 

    Repair the TCU branch line.

  3. CHECK POWER SUPPLY AND GROUND CIRCUIT

    Check the power supply and the ground circuit of the TCU. Refer to DIAGNOSIS PROCEDURE .

    Is the inspection result normal?

    YES (Present error) 

    Replace the TCU. Refer to REMOVAL AND INSTALLATION .

    YES (Past error) 

    Error was detected in the TCU branch line.

    NO 

    Repair the power supply and the ground circuit.

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