Diagnosis System

WARNING: This page is about a different car, the 2004 Lexus LS 430. However, it is still accessible from the selected car via links, so may be relevant.

DESCRIPTION
1. The ECM controls the vehicle's immobilizer system functions. Immobilizer system data and the Diagnostic Trouble Code (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 lamp is not illuminated. When the system seems to be malfunctioning, use the hand-held tester to check for malfunctions and perform repairs.
CHECK DLC3
HINT:

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

Fig 1: Checking Dlc3 Terminal Connector
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 2: Specification Terminal Condition
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

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 hand-held tester (with CAN VIM) to the DLC3, turn the ignition switch ON and attempt to use the hand-held tester. If the screen displays UNABLE TO CONNECT TO VEHICLE, a problem may be on the vehicle side or tester side.
- If communication is normal when the tester is connected to another vehicle, inspect the DLC3 of the original vehicle.
- If communication is still impossible 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 3: Identifying Special Tools
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
CHECK BATTERY VOLTAGE
Standard: 11 to 14 V

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