Diagnosis System

DESCRIPTION
1. Engine Immobilizer 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 Immobilizer system even though the security indicator is not illuminated. When the system seems to be malfunctioning, use the Techstream to check for malfunctions and perform repairs.
  
  Fig 1: Identifying Oscilloscope Waveform Graph 2
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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

Courtesy 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.

NOTE: *: Before measuring the resistance, leave the vehicle as is for at least 1 minute and do not operate the ignition switch, the DLC3 may have a malfunction. Repair or replace the harness and connector.

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 Techstream to the DLC3, turn the ignition switch ON and attempt to use the Techstream. If the screen displays a communication error message, 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.