Section 634 (Multiplex Communication System - Diagnostics): Pre-Check

WARNING: This page is about a different car, the 2004 Toyota Camry. However, it is still accessible from the selected car via links, so may be relevant.

MULTIPLEX COMMUNICATION SYSTEM (BEAN)
1. BEAN communication line is used to control the theft warning ECU (theft deterrent ECU). Since the line connects the body and theft warning ECU (theft deterrent ECU) with one line, the communication goes one way from the theft warning ECU (theft deterrent ECU) to the body ECU.
INSPECT OUTPUT OF DIAGNOSTIC BY DOOR OPEN INDICATOR
1. Inspect the battery positive voltage.
  Standard: 10 - 14 V (when engine stopped)
2. Check that the diagnostic outputs.
  NOTE: No abnormality exists in all the following items.
  1. Check that the door open indicator will be on when any of the doors is opened.
    HINT:
    
    In case that the indicator will not be on, the following problems are possible reasons; door open indicator LED defective, wire harness short, courtesy light switch's contact condition defective, multiplex network body ECU defective, etc.
  2. By using SST (diagnosis check wire No. 2), make a short-circuit between terminals TC (13) and CG (4) of the DLC3.
    SST 09843-18040
    
    NOTE: Do not make a short-circuit in any other positions.
    
    Fig 1: Making Short-Circuit Between Terminals TC And CG Of DLC3
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  3. Turn the ignition switch ON and read the number of blinks of the door open indicator.
    HINT:
    
    When 2 or more codes are output simultaneously, display will be started from the smaller numbered code.
    
    Fig 2: Identifying Number Of Blinks Of Door Open Indicator
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  4. When the DTC of the ECU unconnected is displayed, perform an inspection depending on the troubleshooting.
HINT:
- When the communication bus is defective the door open indicator in the meter will not be on and therefore any DTC will not be output.
- When other DTC is output, refer to the DTC table and applicable section.
- When no DTC is output even in the normal condition, problems, such as short-circuit between terminals TC and CG, meter fuses defective etc., may exist.
- When the door open indicator is always on, the wire harness might be short-circuited.