MULTIPLEX COMMUNICATION SYSTEM, Diagnostic DTC:B1271

DTC Code DTC Name
B1271 Combination Meter ECU Communication Stop

DESCRIPTION

This DTC is detected if communication between the combination meter and gateway ECU stops for more than 10 seconds.

DTC No. DTC Detection Condition Trouble Area
B1271 Combination meter ECU communication stops

  • Combination meter

  • Wire harness or connector

WIRING DIAGRAM

A015ZSZE03

INSPECTION PROCEDURE

Tech Tips

If "+B of GND short malfunction of communication bus" DTCs (B1266 and B1267) are detected at the same time as "communication stop" DTC B1271, repair the "+B or GND short malfunction of communication bus" DTCs first Click here.

PROCEDURE


  1. INSPECT FUSE (DOME, MPX-B)


    1. Remove the DOME and MPX-B fuses from the engine room relay block No. 1.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      DOME fuse Always Below 1 Ω
      MPX-B fuse Always Below 1 Ω

    NG

    REPLACE FUSE

    OK

  2. CHECK HARNESS AND CONNECTOR (COMBINATION METER - BATTERY AND BODY GROUND)


    1. A0162IXE07

      Disconnect the J34 connector.

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      J34-23 (B) - Body ground Always 11 to 14 V
      J34-24 (B) - Body ground Always 11 to 14 V
      Standard Resistance
      Tester Connection Condition Specified Condition
      J34-1 (E2) - Body ground Always Below 1 Ω
      J34-13 (ES) - Body ground Always Below 1 Ω

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  3. CHECK HARNESS AND CONNECTOR (COMMUNICATION LINE)


    1. Disconnect the J34, J76, A27 and Q37 connectors.

      A0162WSE02

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      J34-18 (MPX-) - J76-4 (MPI1) Always Below 1 Ω
      J34-6 (MPX+) - A27-6 (MPX2) Always Below 1 Ω
      J34-6 (MPX+) - Q37-26 (M+)*1 Always Below 1 Ω

      Tech Tips

      *1: w/ LEXUS Parking Assist-Sensor System


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (COMMUNICATION LINE)

    OK

    REPLACE COMBINATION METER Click here