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Home >> Lexus >> 2008 >> IS F >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - SFI System Diagnostics (4 Of 4) >> 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 the DTCs

      Result 

      RESULT CHART

      Result Proceed to
      DTC U0101 is output A
      DTC U0101 and other DTCs are output 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 ECU POWER SOURCE CIRCUIT (TCM POWER SOURCE) 
    1. Disconnect the 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
      A58-5 (+B) - Body ground Engine switch on (IG) 11 to 14 V
    4. Reconnect the TCM connector.
      5. Fig 1: Identifying TCM Connector A58
      G05751750Courtesy 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 (TCM - BODY GROUND) 
    1. Disconnect the TCM connector.
    2. Measure the resistance according to the value(s) in the table below

      Standard Resistance 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Condition Condition Specified Condition
      A58-2 (E1) - Body ground Always Below 1 Ω
    3. Reconnect the TCM connector
      4. Fig 2: Identifying TCM Connector A58
      G05751751Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR (TCM - BODY GROUND) 

    OK: Go to next step 

  4. CHECK HARNESS AND CONNECTOR (ECM - TCM) 
    1. Disconnect the ECM connector.
    2. Disconnect the 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
      A6-10 (CAN+) - A58-21 (CAN+) Always Below 1 Ω
      A6-9 (CAN-) - A58-13 (CAN-) Always Below 1 Ω

      Standard Resistance (Check for Short) 

      TESTER CONNECTION SPECIFIED CONDITION CHART

      Tester Connection Condition Specified Condition
      A6-10 (CAN+) or A58-21 (CAN+) - Body ground Always 10 kΩ or higher
      A6-9 (CAN-) or A58-13 (CAN-) - Body ground Always 10 kΩ or higher
    4. Reconnect the ECM connector and TCM connector.
      5. Fig 3: Identifying ECM Connector E6 And TCM Connector A58
      G05751752Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  5. REPLACE ECM 
    1. Replace the ECM (See REMOVAL )
  6. 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 the DTCs.

      Result 

      RESULT CHART

      Result Proceed to
      DTC is not output A
      DTC U0101 is output B

    B: REPLACE TCM  (See REMOVAL )

    A: END 

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