B1278

DESCRIPTION

This DTC is detected when communication between the combination switch (windshield wiper switch) and gateway ECU stops for more than 10 seconds.

DTC No.	DTC Detection Condition	Trouble Area
B1278	Combination switch ECU communication stops	Combination switch assembly (windshield wiper switch) Wire harness

WIRING DIAGRAM

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 B1278, repair the "+B or GND short malfunction of communication bus" DTCs first.

1. INSPECT FUSE (ECU-IG RH, MPX-B)

1. Remove the ECU-IG RH fuse from the main body ECU RH (cowl side J/B RH).

2. Remove the MPX-B fuse from the engine room J/B No. 1.

   Standard resistance:

   Below 1 Ω
   

NG	REPLACE FUSE

OK

2. CHECK WIRE HARNESS (COMBINATION SWITCH ASSEMBLY - BATTERY AND BODY GROUND)

1. Disconnect the J26 ECU connector.

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

   Standard voltage:

   Tester Connection	Condition	Specified Condition
   B (J26-1) - Body ground	Always	10 to 14 V
   IG (J26-2) - Body ground	Engine switch on (IG)	10 to 14 V

   Standard resistance:

   Tester Connection	Specified Condition
   E (J26-5) - Body ground	Below 1 Ω

NG	REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

3. CHECK RESISTANCE OF COMMUNICATION LINE

1. Disconnect the J26, J76 and J55 ECU connectors.

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

   Standard resistance:

   Tester Connection	Specified Condition
   MPX1 (J26-6) - MPD2 (J76-12)	Below 1 Ω
   MPX2 (J26-7) - MPX1 (J55-7)	Below 1 Ω

   Result:

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

B	REPAIR OR REPLACE HARNESS OR CONNECTOR AND REPLACE COMBINATION SWITCH ASSEMBLY
C	REPAIR OR REPLACE HARNESS OR CONNECTOR

A
REPLACE COMBINATION SWITCH ASSEMBLY