Dtc B1266 Instrument Panel System Communication Bus Malfunction (+B Short)

Communication System. Lexus Gs430, Gs300. Uzs190 Grs190
Multiplex Communication. Lexus Gs430, Gs300. Uzs190 Grs190

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

CHECK DIAGNOSTIC TROUBLE CODE (A ECU)

CHECK DIAGNOSTIC TROUBLE CODE (B ECU)

CHECK WIRE HARNESS BETWEEN A ECU AND B ECU

CHECK DIAGNOSTIC TROUBLE CODE (C ECU)

CHECK WIRE HARNESS BETWEEN B ECU AND C ECU

CHECK WIRE HARNESS BETWEEN GATEWAY ECU AND A ECU OR C ECU

DTC B1266 Instrument Panel System Communication Bus Malfunction (+B Short)

DTC B1267 Instrument Panel System Communication Bus Malfunction (GND Short)


DESCRIPTION

When a +B or body ground short circuit is detected on the instrument panel system communication bus (BEAN), the instrument panel system communication bus (BEAN) is disabled and a DTC is output.

DTC No.
DTC Detection Condition
Trouble Area
B1266
Instrument panel system communication circuit and +B battery system short
  1. Network gateway ECU
  2. Cowl side junction block ECU LH
  3. Integration control and panel assembly
  4. A/C amplifier assembly No. 2 (A/C ECU)
  5. Airbag sensor assembly center
  6. Cowl side junction block RH
  7. Center junction block RH
  8. Combination switch assembly (windshield wiper switch)
  9. Wire harness
B1267
Instrument panel system communication circuit and body ground short
  1. Network gateway ECU
  2. Cowl side junction block ECU LH
  3. Integration control and panel assembly
  4. A/C amplifier assembly No. 2 (A/C ECU)
  5. Airbag sensor assembly center
  6. Cowl side junction block RH
  7. Center junction block RH
  8. Combination switch assembly (windshield wiper switch)
  9. Wire harness

WIRING DIAGRAM


Lexus Gs430, Gs300. Uzs190 Grs190.Multiplex Communication.Multiplex Communication System. Dtc B1266 Instrument Panel System Communication Bus Malfunction (+B Short)


INSPECTION PROCEDURE

1.CHECK DIAGNOSTIC TROUBLE CODE (A ECU)


  1. Disconnect the A ECU connector and check for DTCs B1266 and B1267.


    Lexus Gs430, Gs300. Uzs190 Grs190.Multiplex Communication.Multiplex Communication System. Dtc B1266 Instrument Panel System Communication Bus Malfunction (+B Short)

    OK:
    DTCs B1266 and B1267 are not output.
    NOTICE:
    Reconnect the connector before starting the next check.
    HINT:
    1. The A ECU in the instrument panel system bus represents the combination switch (windshield wiper switch).
    2. If the result is as specified, the disconnected A ECU (combination switch (windshield wiper switch)) is malfunctioning.


NG
Go to step 2
OK

REPLACE A ECU

2.CHECK DIAGNOSTIC TROUBLE CODE (B ECU)


  1. Disconnect the A ECU and B ECU connectors and check for DTCs B1266 and B1267.


    Lexus Gs430, Gs300. Uzs190 Grs190.Multiplex Communication.Multiplex Communication System. Dtc B1266 Instrument Panel System Communication Bus Malfunction (+B Short)

    OK:
    DTCs B1266 and B1267 are not output.
    NOTICE:
    Disconnect the connectors one by one. Reconnect the connectors before starting the next check.
    HINT:
    1. The B ECU in the instrument panel system bus represents one of the following: airbag sensor assembly center, A/C amplifier No. 2, cowl side junction block RH, center junction block RH.
    2. If the result is as specified, the disconnected B ECU (one of the ECUs from the above list) or the wire harness between the A ECU and B ECU is malfunctioning.


NG
Go to step 3
OK


3.CHECK WIRE HARNESS BETWEEN A ECU AND B ECU


  1. Disconnect the B ECU connector and check for DTCs B1266 and B1267.


    Lexus Gs430, Gs300. Uzs190 Grs190.Multiplex Communication.Multiplex Communication System. Dtc B1266 Instrument Panel System Communication Bus Malfunction (+B Short)

    OK:
    DTCs B1266 and B1267 are not output.
    NOTICE:
    Reconnect the connector before starting the next check.
    HINT:
    If the result is as specified, the wire harness between the A ECU and B ECU is functioning normally but the disconnected B ECU is malfunctioning.


NG
REPAIR OR REPLACE WIRE HARNESS BETWEEN A ECU AND B ECU
OK

REPLACE B ECU

4.CHECK DIAGNOSTIC TROUBLE CODE (C ECU)


  1. Disconnect the B ECU and C ECU connectors and check for DTCs B1266 and B1267.


    Lexus Gs430, Gs300. Uzs190 Grs190.Multiplex Communication.Multiplex Communication System. Dtc B1266 Instrument Panel System Communication Bus Malfunction (+B Short)

    OK:
    DTCs B1266 and B1267 are not output.
    NOTICE:
    Disconnect the connectors one by one. Reconnect the connectors before starting the next check.
    HINT:
    1. The C ECU in the instrument panel system bus represents the integration control and panel assembly.
    2. If the result is as specified, the disconnected C ECU (integration control and panel assembly) or the wire harness between the B ECU and C ECU is malfunctioning.


NG
Go to step 6
OK


5.CHECK WIRE HARNESS BETWEEN B ECU AND C ECU


  1. Disconnect the C ECU connector and check for DTCs B1266 and B1267.


    Lexus Gs430, Gs300. Uzs190 Grs190.Multiplex Communication.Multiplex Communication System. Dtc B1266 Instrument Panel System Communication Bus Malfunction (+B Short)

    OK:
    DTCs B1266 and B1267 are not output.
    NOTICE:
    Reconnect the connector before starting the next check.
    HINT:
    If the result is as specified, the wire harness between the B ECU and C ECU is functioning normally but the disconnected C ECU is malfunctioning.


NG
REPAIR OR REPLACE WIRE HARNESS BETWEEN B ECU AND C ECU
OK

REPLACE C ECU

6.CHECK WIRE HARNESS BETWEEN GATEWAY ECU AND A ECU OR C ECU


  1. Check for a short circuit in B+ or body ground.


    Lexus Gs430, Gs300. Uzs190 Grs190.Multiplex Communication.Multiplex Communication System. Dtc B1266 Instrument Panel System Communication Bus Malfunction (+B Short)

    1. Disconnect the A ECU, C ECU and gateway ECU connectors.

    2. Measure the resistance and voltage of the wire harness side connectors.

      Standard voltage:

      Tester Connection
      		Specified Condition
      A ECU connector / Network gateway ECU connector - Body ground
      		Below 1 V
      C ECU connector / Network gateway ECU connector - Body ground
      		Below 1 V

      Standard resistance:

      Tester Connection
      		Specified Condition
      A ECU connector / Network gateway ECU connector - Body ground
      		10 kΩ or higher
      C ECU connector / Network gateway ECU connector - Body ground
      		10 kΩ or higher
      HINT:
      1. The A ECU in the instrument panel system bus represents the combination switch (windshield wiper switch).
      2. The C ECU in the instrument panel system bus represents the integration control and panel assembly.


NG
REPAIR OR REPLACE WIRE HARNESS BETWEEN GATEWAY ECU AND A ECU OR C ECU
OK

REPLACE NETWORK GATEWAY ECU