B1278

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

DTC B1278 - Combination Switch ECU Communication Stop

DESCRIPTION

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






WIRING DIAGRAM





INSPECTION PROCEDURE

PROCEDURE

1. CHECK COMBINATION SWITCH ASSEMBLY (OPERATION)
(a) Check that the turn signal switch can operate the turn signal light normally.
OK:
Turn signal switch can operate the turn signal light normally.
OK -- REPLACE TURN SIGNAL SWITCH ASSEMBLY
NG -- Continue to next step.
2. CHECK WIRE HARNESS (TURN SIGNAL SWITCH - BATTERY AND BODY GROUND)




(a) Disconnect the C11 switch connector.
(b) Measure the voltage and resistance of the wire harness side connector.
Standard voltage:






Standard resistance:






NG -- REPAIR OR REPLACE HARNESS AND CONNECTOR
OK -- Continue to next step.
3. CHECK RESISTANCE OF COMMUNICATION LINE




(a) Disconnect the C11 switch connector.
(b) Disconnect the L24 and T8 ECU connectors.
(c) Measure the resistance of the wire harness side connectors.
Standard resistance:






Result





C -- REPAIR OR REPLACE HARNESS AND CONNECTOR
B -- REPLACE TURN SIGNAL SWITCH ASSEMBLY AND REPAIR OR REPLACE HARNESS AND CONNECTOR
A -- REPLACE TURN SIGNAL SWITCH ASSEMBLY