DTC B1279 Rain Sensor Communication Stop

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	Rain sensor Wire harness

Dtc B1279 Rain Sensor Communication Stop. MULTIPLEX COMMUNICATION. Lexus IS250 IS220d GSE20 ALE20

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)

Disconnect the R7 connector.

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

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

2.CHECK RESISTANCE OF COMMUNICATION LINE

Disconnect the R7 and R5 ECU connectors.

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 (R7-2) - Body ground 10 kΩ or higher

REPAIR OR REPLACE HARNESS OR CONNECTOR

REPLACE RAIN SENSOR

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

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