DTC    B1278    Combination Switch ECU Communication Stop

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DESCRIPTION

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

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

WIRING DIAGRAM


B108883E04


INSPECTION PROCEDURE

1.CHECK OPERATION

  1. Check that the windshield wiper switch can operate the wipers normally.

    OK:
    Windshield wiper switch can operate wipers normally.



NG
Go to step 2
OK

REPLACE WINDSHIELD WIPER SWITCH ASSEMBLY 

2.CHECK WIRE HARNESS (COMBINATION SWITCH ASSEMBLY (WINDSHIELD WIPER SWITCH) - BATTERY AND BODY GROUND)
B109182E02

  1. Disconnect the L22 combination switch connector.

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

    Standard Resistance:
    Tester Connection
    		Specified Condition
    L22-5 (E) - Body ground
    		Below 1 Ω

    Standard Voltage:
    Tester Connection
    		Specified Condition
    L22-1 (B) - Body ground
    		10 to 14 V



NG
REPAIR OR REPLACE HARNESS AND CONNECTOR
OK


3.CHECK RESISTANCE OF COMMUNICATION LINE

E109791E04

  1. Disconnect the L22 switch connector.

  1. Disconnect the L68 ECU and 2F Front Controller ECU connectors.

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

    Standard resistance:
    Tester Connection
    		Specified Condition
    L22-6 (MPX1) - L68-21 (MPX2)
    		Below 1 Ω
    L22-7 (MPX2) - 2F-5 (MPX1)
    		Below 1 Ω

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



B
REPLACE WINDSHIELD WIPER SWITCH ASSEMBLY AND HARNESS AND CONNECTOR

C
REPAIR OR REPLACE HARNESS AND CONNECTOR
A

REPLACE COMBINATION SWITCH ASSEMBLY (WINDSHIELD WIPER SWITCH ASSEMBLY)