Lexus IS250 · Service Manual COMMUNICATION SYSTEM

B1279

Diagnostic trouble codes

DESCRIPTION

This DTC is detected when communication between the rain sensor and gateway ECU stops for more than 10 seconds.
DTC No.
 DTC Detection Condition
 Trouble Area
B1279
 Rain sensor communication stops
  1. Rain sensor
  2. Wire harness

WIRING DIAGRAM

B133475E01

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 B1279, repair the "+B or GND short malfunction of communication bus" DTCs first.


1. CHECK WIRE HARNESS (RAIN SENSOR - BATTERY AND BODY GROUND)

  1. B131022E01
    Disconnect the R7 connector.

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

    Standard voltage:
    Tester Connection
    		 Condition
    		 Specified Condition
    SIG (R7-1) - Body ground
    		 Engine switch on (IG)
    		 10 to 14 V

    Standard resistance:
    Tester Connection
    		 Specified Condition
    ES (R7-3) - Body ground
    		 Below 1 Ω



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK


2. CHECK RESISTANCE OF COMMUNICATION LINE

  1. B131023E01
    Disconnect the R7 and R5 ECU connectors.

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

    Standard resistance:
    Tester Connection
    		 Specified Condition
    MPX (R7-2) - MPX1 (R5-37)
    		 Below 1 Ω
    MPX (R7-21) - Body ground
    		 10 kΩ or higher



NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE RAIN SENSOR


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