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Home >> Lexus >> 2008 >> LS 460L >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - DTC P1023 - P2A03, DTC U0101 >> DTC U0101 Lost Communication with TCM >> Inspection Procedure
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Inspection Procedure

  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC U0101) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream ON.
    4. Enter the following menus: Powertrain / Engine / Trouble Codes.
    5. Read DTCs.

      Result 

      RESULT CHART

      Display (DTC output) Proceed to
      U0101 A
      U0101 and other DTCs B

      HINT:

      If any DTCs other than U0101 are output, troubleshoot those DTCs first.

    B: GO TO DTC CHART  (See DIAGNOSTIC TROUBLE CODE CHART )

    A: Go to next step. 

  2. INSPECT TCM 
    1. Disconnect the A12 TCM connector.
    2. Turn the engine switch on (IG).
    3. Measure the voltage according to the value(s) in the table below.

      Standard Voltage 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Switch Condition Specified Condition
      A12-6 (+B) - Body ground Engine switch on (IG) 11 to 14 V
    4. Disconnect the E5 TCM connector.
    5. Measure the resistance according to the value(s) in the table below.

      Standard Resistance 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Condition Specified Condition
      E5-7 (E1) - Body ground Always Below 1 Ω
      Fig 1: Identifying Terminals Of A12 TCM Connector
      G04942931Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: GO TO TCM POWER SOURCE CIRCUIT  (See TCM POWER SOURCE CIRCUIT )

    OK: Go to next step. 

  3. CHECK HARNESS AND CONNECTOR (ECM - TCM) 
    1. Disconnect the A13 ECM connector.
    2. Disconnect the A12 TCM connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance (Check for open) 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Condition Specified Condition
      A13-9 (CAN-) - A12-19 (CAN-) Always Below 1 Ω
      A13-10 (CAN+) - A12-18 (CAN+) Always Below 1 Ω

      Standard Resistance (Check for short) 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Condition Specified Condition
      A13-9 (CAN-) or A12-19 (CAN-) - Body ground Always 10 kΩ or higher
      A13-10 (CAN+) - A12-18 (CAN+) - Body ground Always 10 kΩ or higher
      Fig 2: Identifying Terminals Of A13 And A12 ECM Connectors
      G04942932Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step. 

  4. REPLACE ECM 
    1. Replace the ECM (see REMOVAL ).
  5. CHECK WHETHER DTC OUTPUT RECURS (DTC U0101) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG) and turn the Techstream ON.
    3. Enter the following menus: Powertrain / Engine / Trouble Codes.
    4. Read DTCs.

      Result 

      RESULT CHART

      Display (DTC output) Proceed to
      No output A
      U0101 B

    B: REPLACE TCM  (See REMOVAL )

    A: END 

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