Diagnosis System

1. The main body ECU controls the functions of the multiplex communication system on the vehicle. Data of the multiplex communication system and the Diagnostic Trouble Codes (DTC) can be read through the Data Link Connector 3 (DLC3) of the vehicle.

1. The ECU uses ISO 15765-4 for communication. The terminal arrangement of the DLC3 complies with ISO 15031-3 and matches the ISO 15765-4 format.
   Fig 1: Identifying DLC3 Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   DLC3 CONNECTOR TERMINALS
   
   

   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)	HIGH-level CAN bus line	Ignition switch OFF(1)	54 to 69 Ω
   CANH (6) - CG (4)	HIGH-level CAN bus line	Ignition switch OFF(1)	200 Ω or more
   CANL (14) - CG (4)	LOW-level CAN bus line	Ignition switch OFF(1)	200 Ω or more
   CANH (6) - BAT (16)	HIGH-level CAN bus line	Ignition switch OFF(1)	6 kΩ or more
   CANL (14) - BAT (16)	LOW-level CAN bus line	Ignition switch OFF(1)	6 kΩ or more
   (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.

2. Intelligent Tester

   HINT:

   Connect the cable of the intelligent tester to the CAN VIM, connect the CAN VIM to the DLC3, turn the ignition switch ON* and attempt to use the tester. If the display indicates that a communication error has occurred, there is a problem either with the vehicle or with the tester.

   • If communication is normal when the tester is connected to another vehicle, inspect the DLC3 of the original vehicle.
   • If communication is still not possible when the tester is connected to another vehicle, the problem may be in the tester itself. Consult the Service Department listed in the tester's instruction manual.
     Fig 2: Connecting Intelligent Tester To DLC3

     Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Standard voltage: 

11 to 14 V 

If the voltage is below 11V, recharge or replace the battery before proceeding.