Lexus IS250 · Service Manual COMMUNICATION SYSTEM

B1266

Diagnostic trouble codes

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

B133217E01

INSPECTION PROCEDURE


1. CHECK DIAGNOSTIC TROUBLE CODE (A ECU)

  1. Disconnect the A ECU connector and check for DTCs B1266 and B1267.B079627E09

    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.B079628E13

    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.B079912E09

    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.B079630E08

    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.B079631E08

    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.B079632E07

    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


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