Section 777 (Multiplex Communication System - Diagnosis): Pre-Check: Notes

1. As shown in Fig 1 , each ECU of this vehicle is connected by communication bus and it transmits is self-diagnosed by body ECU and it memorizes DTC when it detects communication stop to ECU or communication bus +B short or GND short. There is a possibility the Body ECU cannot self- diagnose accurately unless it doesn't work normal. So please note that the trouble- shooting of Body electrical system should be done after confirming if body ECU and open door indicator works normal by 2" BASIC INSPECTION" described later
   Fig 1: ECU Communication Transition Signal Diagram

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2. If DTC of ECU communication stop is output, there is a possibility of connector disconnection or 2 communication buses open. it will not become abnormal with only communication bus open
   Fig 2: Identifying Conditions For ECU Output Of DTC

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3. If 2 communication buses are open at the position as shown in Fig 3 DTC of ECU communication stop between those 2 buses is output
   Fig 3: Identifying Open Communication Buses (Preventing Communication With 3 ECUs)

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Basic inspection is for checking body ECU normal operation