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Diagnosis System

  1. DESCRIPTION 
    1. Engine immobiliser system data and Diagnostic Trouble Codes (DTCs) can be read through the vehicle's Data Link Connector 3 (DLC3). In some cases, a malfunction may be occurring in the immobiliser system even though the security indicator is not illuminated. When the system seems to be malfunctioning, use the intelligent tester to check for malfunctions and perform repairs.
      Fig 1: Identifying Oscilloscope Waveform Graph 2
      G05292506Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  2. CHECK DLC3 

    The vehicle's ECU uses the ISO 15765-4 communication protocol. The terminal arrangement of the DLC3 complies with SAE J1962 and matches the ISO 15765-4 format.

    Fig 2: Identifying DLC3 Connector Terminals (CANL And BAT)
    G05292507Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    ECU CONNECTOR TERMINAL SPECIFIED CONDITION

    Symbols (Terminal No.) Terminal Description Condition Specified Condition
    SIL (7) - SG (5) Bus "+" line During transmission Pulse generation
    CG (4) - Body ground Chassis ground Always Below 1 Ω
    SG (5) - Body ground Signal ground Always Below 1 Ω
    BAT (16) - Body ground Battery positive Always 11 to 14 V
    CANH (6) - CANL (14) CAN bus line Ignition switch OFF(1) 54 to 69 Ω
    CANH (6) - Battery positive HIGH-level CAN bus line Ignition switch OFF(1) 200 Ω or higher
    CANH (6) - CG (4) HIGH-level CAN bus line Ignition switch OFF(1) 200 Ω or higher
    CANL (14) - Battery positive LOW-level CAN bus line Ignition switch OFF(1) 6 kΩ or higher
    CANL (14) - CG (4) LOW-level CAN bus line Ignition switch OFF(1) 6 kΩ or higher
    NOTE:
    (1) Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the ignition switch, any other switches or the doors.

    If the result is not as specified, the DLC3 may have a malfunction. Repair or replace the harness and connector.

    HINT:

    Connect the cable of the intelligent tester (with CAN VIM) to the DLC3, turn the ignition switch ON and attempt to use the intelligent tester. If the screen displays UNABLE TO CONNECT TO VEHICLE, a problem exists in the vehicle side or the tester side.

    • If communication is normal when the tester is connected to another vehicle, inspect the DLC3 on the original vehicle.
    • If communication is still not possible when the tester is connected to another vehicle, the problem is probably in the tester itself. Consult the Service Department listed in the tester's instruction manual.
      Fig 3: Connecting Cable Of Intelligent Tester (With CAN VIM) To DLC3
      G05292508Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002