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Home › Lexus › 2008 › GS 450h › Repair and Diagnosis › Brakes › Traction Control › Brake Control › Electronically Controlled Brake System › DTC C1378/44 Capacitor Communication Malfunction › Inspection Procedure

Inspection Procedure

NOTE: When replacing the skid control ECU, perform initialization of linear solenoid valve and calibration (see INITIALIZATION  ).
  1. INSPECT BRAKE CONTROL POWER SUPPLY 
    1. Disconnect the U27 power supply connector.
    2. Measure the voltage according to the value(s) in the table below.

      Standard voltage 

      STANDARD VOLTAGE SPECIFICATION

      Tester Connection Specified Condition
      U27-S (161) - Body ground 10 to 14 V
    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      STANDARD RESISTANCE SPECIFICATION

      Tester Connection Specified Condition
      U27-14 (GND) - Body ground Below 1 Ω
      4. Fig 1: Identifying U27 Power Supply Connector
      G05816371Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR (IG1 OR GND CIRCUIT) 

    OK: Go to next step 

  2. CHECK WIRE HARNESS (SKID CONTROL ECU - BRAKE CONTROL POWER SUPPLY) 
    1. Disconnect the A13 ECU connector.
    2. Disconnect the U27 power supply connector.
    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance 

      STANDARD RESISTANCE SPECIFICATION

      Tester Connection Specified Condition
      A13-8 (ENA) - U27-12 (ENA) Below 1 Ω
      A13-23 (FAIL) - U27-13 (FAIL) Below 1 Ω
      A13-8 (ENA) - Body ground 10 kΩ or higher
      A13-23 (FAIL) - Body ground 10 kΩ or higher
      4. Fig 2: Identifying A13 ECU And U27 Power Supply Connectors
      G05816372Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

    NG: REPAIR OR REPLACE HARNESS OR CONNECTOR 

    OK: Go to next step 

  3. RECONFIRM DTC 
    1. Clear the DTC (see DTC CHECK/CLEAR  ).
    2. Turn the power switch ON (IG).
    3. Check if the same DTC is recorded (see DTC CHECK/CLEAR  ).

      HINT:

      Reinstall the sensor, connectors, etc. and restore the vehicle to its prior condition before rechecking for DTCs.

      Result 

      RESULT REFERENCE

      Condition Proceed to
      DTC (C1378/44) is not output A
      DTC (C1378/44) is output B

    B: Go to step 4 

    A: END 

  4. CHECK FREEZE FRAME DATA 
    1. Check the information code from the Freeze Frame Data memorized when the DTC (C1378/44) is stored (see FREEZE FRAME DATA  ).

      Result 

      RESULT REFERENCE

      Condition Proceed to
      Information code is not output A
      Information code (112) is output B

    B: REPLACE BRAKE CONTROL POWER SUPPLY  (See REMOVAL  )

    A: REPLACE SKID CONTROL ECU  (See REMOVAL  )

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