ENGINE IMMOBILISER SYSTEM(w/o Entry and Start System), Diagnostic DTC:B1572

DTC Code DTC Name
B1572 Immobiliser System Communication Malfunction

DESCRIPTION


DTC Code DTC Detection Condition Trouble Area
B1572 When there is a problem in communication between the main body ECU (network gateway ECU) and ECM.

  • Harness or connector

  • ECM

  • Instrument panel junction block assembly

  • Main body ECU (network gateway ECU)

WIRING DIAGRAM

A004KWKE03
*a to MAIN Fuse
*b BMPX
*c Main Body ECU (Network Gateway ECU)
*d Instrument Panel Junction Block Assembly

CAUTION / NOTICE / HINT

Note


  • If the main body ECU (network gateway ECU) or ECM is replaced, refer to Service Bulletin.

  • Inspect the fuses for circuits related to this system before performing the following inspection procedure.

PROCEDURE


  1. CHECK HARNESS AND CONNECTOR (BATTERY, BODY GROUND)


    1. Disconnect the A73 and D6 main body ECU (network gateway ECU) connectors.

    2. Disconnect the 3A, 3B and 3C instrument panel junction block assembly connectors.

    3. A004J2PE05
      Text in Illustration
      *a

      Component without harness connected

      (Instrument Panel Junction Block Assembly)

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      3A-27 - Body ground Always 11 to 14 V
      3C-19 - Body ground Always 11 to 14 V

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      3B-18 - Body ground Always Below 1 Ω
      A73-4 (GND) - Body ground Always Below 1 Ω
      D6-1 (GND) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  2. INSPECT INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY


    1. Remove the instrument panel junction block assembly Click here.

    2. Remove the main body ECU (network gateway ECU) from the instrument panel junction block assembly.

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

      A004HZAE02
      Text in Illustration
      *a

      Component without harness connected

      (Instrument Panel Junction Block Assembly)

      		 - -
      Standard Resistance
      Tester Connection Condition Specified Condition
      MB-1 (BECU) - 3A-27 Always Below 1 Ω
      MB-32 (BMPX) - 3C-19 Always Below 1 Ω
      MB-11 (GND) - 3B-18 Always Below 1 Ω

    NG

    REPLACE INSTRUMENT PANEL JUNCTION BLOCK ASSEMBLY Click here

    OK

  3. CHECK HARNESS AND CONNECTOR (MAIN BODY ECU (NETWORK GATEWAY ECU) - ECM)


    1. Disconnect the A73 main body ECU (network gateway ECU) connector.

    2. Disconnect the A35 and A36 ECM connectors.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      A73-9 (IMO) - Body ground Always Below 1 V
      A35-25 (IMO) - Body ground Always Below 1 V
      Standard Resistance
      Tester Connection Condition Specified Condition
      A73-9 (IMO) - A35-25 (IMO) Always Below 1 Ω
      A36-4 (E01) - Body ground Always Below 1 Ω
      A73-9 (IMO) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. REPLACE ECM


    1. Temporarily replace the ECM with a new or known good one Click here.

    2. Register the ECU communication ID (Refer to Service Bulletin).


    NEXT

  5. CHECK FOR DTC


    1. Turn the ignition switch to ON and wait for 5 seconds.

    2. Check for DTCs Click here.

      OK
      DTC B1572 is not output

    OK

    END (ECM WAS DEFECTIVE)

    NG

    REPLACE MAIN BODY ECU (NETWORK GATEWAY ECU) Click here