Lexus IS250 · Service Manual COMMUNICATION SYSTEM

B1273

Diagnostic trouble codes

DESCRIPTION

This DTC is detected when communication between the sliding roof control ECU and gateway ECU stops for more than 10 seconds.
DTC No.
 DTC Detection Condition
 Trouble Area
B1273
 Sliding roof control ECU communication stops
  1. Sliding roof control ECU
  2. Wire harness

WIRING DIAGRAM

B133427E01

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" DTCB1273, repair the "+B or GND short malfunction of communication bus" DTCs first.


1. INSPECT FUSE (S/ROOF)

  1. Remove the S/ROOF 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 (SLIDING ROOF CONTROL ECU - BATTERY AND BODY GROUND)

  1. B131016E01
    Disconnect the R6 ECU connector.

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

    Standard voltage:
    Tester Connection
    		 Condition
    		 Specified Condition
    B (R6-5) - Body ground
    		 Always
    		 10 to 14 V

    Standard resistance:
    Tester Connection
    		 Specified Condition
    E (R6-7) - Body ground
    		 Below 1 Ω



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


3. CHECK RESISTANCE OF COMMUNICATION LINE

  1. B131017E01
    Disconnect the R6 and R5 connectors.

  1. Measure the resistance between the specified terminals on the wire harness side connectors.

    Standard resistance:
    Tester Connection
    		 Specified Condition
    MPX1 (R6-10) - MPX2 (R5-38)
    		 Below 1 Ω
    MPX1 (R6-10) - Body ground
    		 10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE SLIDING ROOF CONTROL ECU


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