Dtc B1266 Short To B+ In Instrument Panel System Communication Bus Malfunction

Communication System. Lexus Is250, Is220D. Gse20 Ale20
Multiplex Communication. Lexus Is250, Is220D. Gse20 Ale20

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 Short to B+ in Instrument Panel System Communication Bus Malfunction

DTC B1267 Short to GND in Instrument Panel System Communication Bus Malfunction


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. Gateway ECU
  2. Air conditioning amplifier (A/C ECU)
  3. AFS ECU
  4. Combination meter ECU
  5. Wire harness
B1267
Instrument panel system communication circuit and body ground short
  1. Gateway ECU
  2. Air conditioning amplifier (A/C ECU)
  3. AFS ECU
  4. Combination meter ECU
  5. Wire harness

WIRING DIAGRAM


Lexus Is250, Is220D. Gse20 Ale20.Multiplex Communication.Multiplex Communication System. Dtc B1266 Short To B+ In Instrument Panel System Communication Bus Malfunction


INSPECTION PROCEDURE

1.CHECK DIAGNOSTIC TROUBLE CODE (A ECU)


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


    Lexus Is250, Is220D. Gse20 Ale20.Multiplex Communication.Multiplex Communication System. Dtc B1266 Short To B+ In Instrument Panel System Communication Bus Malfunction

    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


2.CHECK DIAGNOSTIC TROUBLE CODE (B ECU)


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


    Lexus Is250, Is220D. Gse20 Ale20.Multiplex Communication.Multiplex Communication System. Dtc B1266 Short To B+ In Instrument Panel System Communication Bus Malfunction

    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 B ECU in the instrument panel system bus represents the AFS ECU.
    2. If the result is as specified, the disconnected B ECU (AFS ECU) 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 4
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 Is250, Is220D. Gse20 Ale20.Multiplex Communication.Multiplex Communication System. Dtc B1266 Short To B+ In Instrument Panel System Communication Bus Malfunction

    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

4.CHECK DIAGNOSTIC TROUBLE CODE (C ECU)


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


    Lexus Is250, Is220D. Gse20 Ale20.Multiplex Communication.Multiplex Communication System. Dtc B1266 Short To B+ In Instrument Panel System Communication Bus Malfunction

    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 combination meter ECU.
    2. If the result is as specified, the disconnected C ECU (combination meter ECU) or the wire harness between the B ECU and C ECU is malfunctioning.


NG
Go to step 6
OK


Go to step 6

5.CHECK WIRE HARNESS BETWEEN B ECU AND C ECU


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


    Lexus Is250, Is220D. Gse20 Ale20.Multiplex Communication.Multiplex Communication System. Dtc B1266 Short To B+ In Instrument Panel System Communication Bus Malfunction

    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

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 Is250, Is220D. Gse20 Ale20.Multiplex Communication.Multiplex Communication System. Dtc B1266 Short To B+ In Instrument Panel System Communication Bus Malfunction

    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/gateway ECU connector - Body ground
      		Below 1 V
      C ECU connector/gateway ECU connector - Body ground
      		Below 1 V

      Standard resistance:

      Tester Connection
      		Specified Condition
      A ECU connector/gateway ECU connector - Body ground
      		10 kΩ or higher
      C ECU connector/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 combination meter ECU.


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

REPLACE GATEWAY ECU