Lexus IS250 · Service Manual COMMUNICATION SYSTEM

B1262

Diagnostic trouble codes

DESCRIPTION

  1. This DTC is detected when communication between the air conditioning amplifier (A/C ECU) and gateway ECU stops for more than 10 seconds.
DTC No.
DTC Detection Condition
Trouble Area
B1262
Air conditioning amplifier (A/C ECU) communication stops
  1. Air conditioning amplifier (A/C ECU)
  2. Wire harness

WIRING DIAGRAM

B110899E02

INSPECTION PROCEDURE

HINT:
When "+B of GND short malfunction of communication bus" DTCs (B1214 and B1215) are detected at the same time as "communication stop" DTC B1262, repair the "+B or GND short malfunction of communication bus" DTCs first.


1. CHECK FUSE (A/C)
  1. Remove the A/C fuse from the main body ECU LH (cowl side J/B LH).

  1. Measure the resistance of the fuse.

    Standard resistance:
    Below 1 Ω



NG
REPLACE FUSE
OK


2. CHECK WIRE HARNESS (AIR CONDITIONING AMPLIFIER - BATTERY AND BODY GROUND)

  1. B110961E01
    Disconnect the J58 ECU connector.

  1. Measure the voltage and resistance of the wire harness side connector.

    Standard voltage:
    Tester Connection
    Condition
    Specified Condition
    B (J58-1) - Body ground
    Always
    10 to 14 V

    Standard resistance:
    Tester Connection
    Specified Condition
    GND (J58-20) - Body ground
    Below 1 Ω



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


3. CHECK RESISTANCE OF COMMUNICATION LINE

  1. B110962E01
    Disconnect the J58, A27, J34 and J76 ECU connectors.

  1. Measure the resistance of the wire harness side connector.

    Standard resistance:
    Tester Connection
    Specified Condition
    *1MPX- (J58-31) - MPX1 (A27-5)
    Below 1 Ω
    *2MPX- (J58-31) - MPX+ (J34-6)
    Below 1 Ω
    MPX+ (J58-30) - MPI2 (J76-13)
    Below 1 Ω

    HINT:
    1. *1: w/ Adaptive front-lighting system
    2. *2: w/o Adaptive front-lighting system

    Result:
    Result
    Proceed to
    Both are OK
    A
    One is OK
    B
    Both are NG
    C



B
REPLACE AIR CONDITIONING AMPLIFIER AND REPAIR OR REPLACE HARNESS OR CONNECTOR

C
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE AIR CONDITIONING AMPLIFIER ASSEMBLY


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