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

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

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DESCRIPTION

When a +B short circuit 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 code is output.

DTC No.
DTC Detection Condition
Trouble Area
B1266
Instrument panel system communication circuit and +B battery system short
  1. Multiplex network gateway ECU
  2. Air conditioning amplifier (A/C ECU)
  3. Auto wiper ECU
  4. Center cluster integration panel
  5. Center airbag sensor assembly
  6. Combination meter
  7. Overhead junction block
  8. Rain sensor
  9. Sliding roof control ECU
  10. Wire harness
B1267
Instrument panel system communication circuit and body ground short
  1. Multiplex network gateway ECU
  2. Air conditioning amplifier (A/C ECU)
  3. Auto wiper ECU
  4. Center cluster integration panel
  5. Center airbag sensor assembly
  6. Combination meter
  7. Overhead junction block
  8. Rain sensor
  9. Sliding roof control ECU
  10. Wire harness

WIRING DIAGRAM


B110978E02


INSPECTION PROCEDURE

1.CHECK APPARATUS

  1. Choose the apparatus to be inspected.

    Result:
    Apparatus
    		Go to step
    w/ LEXUS navigation system
    		A
    w/o LEXUS navigation system
    		B



B
Go to step 8
A


2.CHECK DIAGNOSTIC TROUBLE CODE (A ECU)


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


    B079627E04

    OK:
    Neither DTC B1266 nor DTC B1267 is output.

    NOTICE:
    Reconnect the connector before starting the next check.

    HINT:
    1. The A ECU in the instrument panel system bus represents the air conditioning amplifier.
    2. If the result is as specified, the disconnected A ECU (air conditioning amplifier) is malfunctioning.



OK
REPLACE A ECU
NG


3.CHECK DIAGNOSTIC TROUBLE CODE (B ECU)


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


    B079628E07

    OK:
    Neither DTC B1266 nor DTC B1267 is output.

    NOTICE:
    Disconnect the connectors one by one. Reconnect the connectors before starting the next check.

    HINT:
    1. Remove the B ECUs in the following order:
      1. Auto wiper ECU
      2. Center airbag sensor assembly
      3. Combination meter
      4. Rain sensor
      5. Sliding roof control ECU
    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.
    3. After the DTC is cleared, proceed to the next step.



NG
Go to step 5
OK


4.CHECK WIRE HARNESS BETWEEN A ECU AND B ECU


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


    B079912E05

    OK:
    Neither DTC B1266 nor DTC B1267 is output.

    NOTICE:
    Reconnect the connector before starting the next check.

    HINT:
    1. 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 

5.CHECK DIAGNOSTIC TROUBLE CODE (C ECU)


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


    B079630E04

    OK:
    Neither DTC B1266 nor DTC B1267 is 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 center cluster integration panel.
    2. If the result is as specified, the disconnected C ECU (center cluster integration panel) or the wire harness between the B ECU and C ECU is malfunctioning.



NG
Go to step 7
OK


6.CHECK WIRE HARNESS BETWEEN B ECU AND C ECU


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


    B079631E04

    OK:
    Neither DTC B1266 nor DTC B1267 is 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 

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


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


    B079632E02

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

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

      Standard voltage:

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


      Standard resistance:

      Tester Connection
      		Specified Condition
      A ECU connector/multiplex network gateway ECU connector - Body ground
      		10 kΩ or higher
      C ECU connector/multiplex network gateway ECU connector - Body ground
      		10 kΩ or higher

      HINT:
      1. The A ECU in the instrument panel system bus represents the air conditioning amplifier.
      2. The C ECU in the instrument panel system bus represents the center cluster integration panel.



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

REPLACE MULTIPLEX NETWORK GATEWAY ECU 

8.CHECK DIAGNOSTIC TROUBLE CODE (SLIDING ROOF CONTROL ECU)

  1. Disconnect the sliding roof control ECU connector and check for DTCs B1266 and B1267.

    OK:
    Neither DTC B1266 nor DTC B1267 is output.

    NOTICE:
    Reconnect the connector before starting the next check.



OK
REPLACE SLIDING ROOF CONTROL ECU
NG


9.CHECK DIAGNOSTIC TROUBLE CODE (RAIN SENSOR)

  1. Disconnect the rain sensor connector and check for DTCs B1266 and B1267.

    OK:
    Neither DTC B1266 nor DTC B1267 is output.

    NOTICE:
    Reconnect the connector before starting the next check.



OK
REPLACE RAIN SENSOR
NG


10.CHECK DIAGNOSTIC TROUBLE CODE (A ECU)


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


    B079627E04

    OK:
    Neither DTC B1266 nor DTC B1267 is output.

    NOTICE:
    Reconnect the connector before starting the next check.

    HINT:
    1. The A ECU in the instrument panel system bus represents the combination meter.
    2. If the result is as specified, the disconnected A ECU (combination meter) is malfunctioning.



OK
REPLACE A ECU
NG


11.CHECK DIAGNOSTIC TROUBLE CODE (B ECU)


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


    B079628E07

    OK:
    Neither DTC B1266 nor DTC B1267 is output.

    NOTICE:
    Disconnect the connectors one by one. Reconnect the connectors before starting the next check.

    HINT:
    1. Remove the B ECUs in the following order:
      1. Center airbag sensor assembly
      2. Auto wiper ECU
    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.
    3. After the DTC is cleared, proceed to the next step.



NG
Go to step 13
OK


12.CHECK WIRE HARNESS BETWEEN A ECU AND B ECU


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


    B079912E05

    OK:
    Neither DTC B1266 nor DTC B1267 is 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 

13.CHECK DIAGNOSTIC TROUBLE CODE (C ECU)


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


    B079630E04

    OK:
    Neither DTC B1266 nor DTC B1267 is 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 air conditioning amplifier.
    2. If the result is as specified, the disconnected C ECU (air conditioning amplifier) or the wire harness between the B ECU and C ECU is malfunctioning.



NG
Go to step 15
OK


14.CHECK WIRE HARNESS BETWEEN B ECU AND C ECU


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


    B079631E04

    OK:
    Neither DTC B1266 nor DTC B1267 is 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 

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


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


    B079632E02

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

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

      Standard voltage:

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


      Standard resistance:

      Tester Connection
      		Specified Condition
      A ECU connector/multiplex network gateway ECU connector - Body ground
      		10 kΩ or higher
      C ECU connector/multiplex network gateway ECU connector - Body ground
      		10 kΩ or higher

      HINT:
      1. The A ECU in the instrument panel system bus represents the combination meter.
      2. The C ECU in the instrument panel system bus represents the air conditioning amplifier.



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

REPLACE MULTIPLEX NETWORK GATEWAY ECU