PRE-CRASH SAFETY SYSTEM, Diagnostic DTC:B2074, B2075

DTC Code DTC Name
B2074 Driver Side Seat Belt Buckle Switch Circuit Malfunction
B2075 Passenger Side Seat Belt Buckle Switch Circuit Malfunction

DESCRIPTION

These DTCs are stored when there is a short or open in the front seat inner belt buckle switch circuit (for driver or passenger side).

DTC No. DTC Detection Condition Trouble Area
B2074 Open or short in front seat inner belt (buckle switch) circuit (for driver side)

  • Wire harness or connector

  • Front seat inner belt assembly LH (for LHD)

  • Front seat inner belt assembly RH (for RHD)

  • Seat belt control ECU
B2075 Open or short in front seat inner belt (buckle switch) circuit (for passenger side)

  • Wire harness or connector

  • Front seat inner belt assembly RH (for LHD)

  • Front seat inner belt assembly LH (for RHD)

  • Seat belt control ECU

WIRING DIAGRAM

A004392E01

INSPECTION PROCEDURE

PROCEDURE


  1. CHECK DTC OUTPUT (PRE-CRASH SAFETY SYSTEM)


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS on.

    4. Enter the following menus: Body Electrical / Pre-Crash / Trouble Codes.

    5. Clear the DTCs Click here.

    6. Recheck for DTCs.

      OK
      DTC B2074 or B2075 is not output.

    NG

    CHECK SEAT BELT CONTROL ECU Click here

    OK

    CHECK FOR INTERMITTENT PROBLEMS (SYMPTOMS SIMULATION) Click here

  2. CHECK SEAT BELT CONTROL ECU


    1. Using an oscilloscope, check the waveform of the seat belt control ECU between the connector terminals.

      A0041L6E01
      Standard
      Signal waveform appears as shown in the illustration.
      Item Contents
      Terminal L4-5 (LBL+) - L4-6 (LBL-)
      L4-4 (RBL+) - L4-3 (RBL-)
      Tool setting 2 V/DIV., 20 ms/DIV.
      Condition Power switch on (IG), front seat belt fastened → unfastened
      Text in Illustration
      *a

      Component with harness connected

      (Seat Belt Control ECU)

      		 *b Front seat belt fastened
      *c Front seat belt unfastened - -
      Result
      Result Proceed to
      OK A
      NG (In case of front seat inner belt assembly RH) B
      NG (In case of front seat inner belt assembly LH) C

    B

    CHECK HARNESS AND CONNECTOR (SEAT BELT CONTROL ECU - FRONT SEAT INNER BELT ASSEMBLY RH) Click here

    C

    CHECK HARNESS AND CONNECTOR (SEAT BELT CONTROL ECU - FRONT SEAT INNER BELT ASSEMBLY LH) Click here

    A

    REPLACE SEAT BELT CONTROL ECU Click here

  3. CHECK HARNESS AND CONNECTOR (SEAT BELT CONTROL ECU - FRONT SEAT INNER BELT ASSEMBLY RH)


    1. Disconnect the L4 seat belt control ECU connector.

    2. Disconnect the S5 front seat inner belt assembly RH connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      L4-4 (RBL+) - S5-5 (RBE+) Always Below 1 Ω
      L4-3 (RBL-) - S5-4 (RBE-) Always Below 1 Ω
      L4-4 (RBL+) or S5-5 (RBE+) - Body ground Always 10 kΩ or higher
      L4-3 (RBL-) or S5-4 (RBE-) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE FRONT SEAT INNER BELT ASSEMBLY RH Click here

  4. CHECK HARNESS AND CONNECTOR (SEAT BELT CONTROL ECU - FRONT SEAT INNER BELT ASSEMBLY LH)


    1. Disconnect the L4 seat belt control ECU connector.

    2. Disconnect the R5 front seat inner belt assembly LH connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard Resistance
      Tester Connection Condition Specified Condition
      L4-5 (LBL+) - R5-5 (LBE+) Always Below 1 Ω
      L4-6 (LBL-) - R5-4 (LBE-) Always Below 1 Ω
      L4-5 (LBL+) or R5-5 (LBE+) - Body ground Always 10 kΩ or higher
      L4-6 (LBL-) or R5-4 (LBE-) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE FRONT SEAT INNER BELT ASSEMBLY LH Click here