B1279 Rain sensor communication stops

DESCRIPTION

This DTC is detected when communication between the rain sensor and multiplex network gateway ECU stops for more than 10 seconds.

DTC No.	DTC Detection Condition	Trouble Area
B1279	Rain sensor communication stops	Rain sensor Wire harness

WIRING DIAGRAM

INSPECTION PROCEDURE

HINT:

When "+B of GND short malfunction of communication bus" DTCs (B1266 and B1267) are detected at the same time as "communication stop" DTC B1279, repair the "+B or GND short malfunction of communication bus" DTCs first.

1. INSPECT FUSE (ECU-IG No.1)

1. Remove the ECU-IG No.1 fuse from the fusible link block.

2. Measure the resistance of the fuse.

   Standard resistance:

   Below 1 Ω
   

NG	REPLACE FUSE

OK

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

1. Disconnect the R7 sensor connector.

2. Measure the voltage of the wire harness side connector.

   Standard voltage:

   Tester Connection	Condition	Specified Condition
   R7-1 (SIG) - Body ground	Ignition switch ON	10 to 14 V

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

   Standard resistance:

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

NG	REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3. CHECK RESISTANCE OF COMMUNICATION LINE

1. Disconnect the G1 and C8 ECU connectors (w/ LEXUS navigation system).

2. Disconnect the C4 and C8 ECU connectors (w/o LEXUS navigation system).
   

3. Measure the resistance of the wire harness side connectors.

   Standard resistance:

   Tester Connection	Specified Condition
   R7-2 (MPX) - G1-12 (MPI2) (*1)	Below 1 Ω
   R7-2 (MPX) - C4-12 (MPX-) (*2)	Below 1 Ω
   R7-2 (MPX) - C8-5 (MPX-)	Below 1 Ω

   *1: w/ LEXUS Navigation System*2: w/o LEXUS Navigation System

NG	REPAIR OR REPLACE HARNESS OR CONNECTOR

OK
REPLACE RAIN SENSOR