Section 341 (Multiplex Communication System - Diagnostics): Pre-Check: Notes

1. As shown in the following illustration, each ECU of this vehicle is connected by communication bus and it transmits each signal by communication. This communication bus 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 that Body ECU cannot self-diagnose accurately unless it doesn't work normal. So, please note that the troubleshooting 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: Multiplex Communication System Diagnosis Diagram (1 Of 3)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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 1 communication bus open.
   Fig 2: Multiplex Communication System Diagnosis Diagram (2 Of 3)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. If 2 communication buses are open at the position as shown in the illustration, DTC of ECU communication stop between those 2 buses is output.
   Fig 3: Multiplex Communication System Diagnosis Diagram (3 Of 3)

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

INSPECT BODY ECU 

1. Check Body ECU operation. 
   NOTE: With this inspection Body ECU CPU can be diagnosed if it works normal or not.

   CHECK: 

   Check if the luggage compartment door opener works normal.

   OK: Go to next step"OPEN DOOR INDICATOR LIGHT INSPECTION". 

   NG: Go to next step. 

2. Check luggage compartment door opener system (Except Body ECU) (See  INSPECTION  ). 

   OK: Replace the Body ECU. 

   NG: Go to next step. 

   Repair of replace malfunction part.