Diagnosis System

DESCRIPTION
1. The network gateway ECU controls the functions of the multiplex communication system of 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.

CHECK DLC3

The vehicle's ECU uses the ISO 15765-4 communication protocol. 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 TERMINALS REFERENCE

Terminal No. (Symbols)	Terminal Description	Condition	Specified condition
7 (SIL) - 5 (SG)	Bus "+" line	During transmission	Pulse generation
4 (CG) - Body ground	Chassis ground	Always	Below 1 Ω
5 (SG) - Body ground	Signal ground	Always	Below 1 Ω
16 (BAT) - Body ground	Battery positive	Always	11 to 14 V
6 (CANH) - 14 (CANL)	CAN bus line	Engine switch off*	54 to 69 Ω
6 (CANH) - 4 (CG)	HIGH-level CAN bus line	Engine switch off*	200 Ω or higher
14 (CANL) - 4 (CG)	LOW-level CAN bus line	Engine switch off*	200 Ω or higher
6 (CANH) - 16 (BAT)	HIGH-level CAN bus line	Engine switch off*	6 kΩ or higher
14 (CANL) - 4 (BAT)	LOW-level CAN bus line	Engine switch off*	6 kΩ or higher

NOTE: *: Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the engine 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:

If the display shows a communication error message when connecting the cable of the intelligent tester to the DLC3, turning the engine switch on (IG) and operating the intelligent tester, there is a problem on the vehicle side or 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.

INSPECT BATTERY VOLTAGE
Standard voltage:

11 to 14 V

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