B1278

MULTIPLEX COMMUNICATION: MULTIPLEX COMMUNICATION SYSTEM: B1278: Combination Switch ECU Communication Stop
B1278 - Combination Switch ECU Communication Stop

DESCRIPTION

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





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.

PROCEDURE

1. INSPECT FUSE (ECU-IG RH, MPX-B)

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

(b) Remove the MPX-B fuse from the engine room J/B No. 1.

Standard resistance:

Below 1 Ohms

NG -- REPLACE FUSE
OK -- Continue to next step.

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

(a) Disconnect the J26 ECU connector.





(b) Measure the voltage and resistance of the wire harness side connector.

Standard voltage:





Standard resistance:





NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR
OK -- Continue to next step.

3. CHECK RESISTANCE OF COMMUNICATION LINE

(a) Disconnect the J26, J76 and J55 ECU connectors.





(b) Measure the resistance between the specified terminals on the wire harness side connectors.

Standard resistance:





Result:





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

C -- REPAIR OR REPLACE HARNESS OR CONNECTOR

A -- REPLACE COMBINATION SWITCH ASSEMBLY