Diagnosis System

DESCRIPTION
1. The transponder key ECU controls the vehicle's immobilizer system functions. Immobilizer system data and Diagnostic Trouble Code (DTC) 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 light is not illuminated.
  
  When the system seems to be malfunctioning, use the Techstream to check for malfunctions and perform repairs.

CHECK DLC3

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

Fig 1: Identifying DLC3 Connector

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

TERMINAL DESCRIPTION

Symbols (Terminals 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

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 a Techstream to the DLC3, turn the ignition switch ON and attempt to use the tester. If the screen displays the message UNABLE TO CONNECT TO VEHICLE, 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 is probably in the tester itself. Consult the Service Department listed in the tester's instruction manual.

INSPECT BATTERY VOLTAGE
1. Measure the battery voltage.
  Standard voltage:
  
  11 to 14 V
  
  If the voltage is below 11V, recharge or replace the battery before proceeding to the next step.