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Self-Diagnostic System: Pre-Check

WARNING: This page is about a different car, the 2002 Lexus ES 300. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Engine Control Module (ECM) controls the function of the immobilizer on the vehicle. Data of the immobilizer or Diagnostic Trouble Code (DTC) can be retrieved from the Data Link Connector 3 (DLC3) of the vehicle. When a trouble occurs in the immobilizer system, the Malfunction Indicator Lamp (MIL) does not come on. Therefore, when there seems to be trouble with the immobilizer system, use the hand-held tester to check and trouble shoot it.
  1. Connect scan tool to DLC3 located under left side of instrument panel. See Fig 2. If scan tool cannot communicate with DLC3 diagnostic line when ignition is turned on and scan tool is operated, there is a problem either on vehicle side or tool side of the link. If communication can be established when scan tool is connected to another vehicle, inspect diagnostic circuit (TC line) of DLC3 circuit in original vehicle. See COMPUTER DATA LINES under SYSTEM WIRING DIAGRAMS article in ELECTRICAL. The vehicle's ECM uses ISO 14230 for communication. The terminal arrangement of the DLC3 complies with SAE J1962 and matches the ISO 14230 format. See Fig 1. If communication is still impossible when scan tool is connected to another vehicle, problem is probably in scan tool itself. Consult the Service Department listed in tool's instruction manual. When communication is established, go to next step.
  2. Turn the ignition switch ON and push the hand-held tester switch ON. Use the hand-held tester to check the DTC(s) and freeze frame data; note them down. (For operating instructions, see the hand-held tester instruction book). Clear the DTC(s). The following procedures will erase the DTC(s) and freeze frame data:
    • Operating the hand-held tester to erase the codes. (For operating instructions, see the hand-held tester instruction book).
    • Disconnecting the battery terminals or EFI fuse for more than 10 seconds.
    Operate system for which complaint was recorded to see if symptom can be recreated. Again retrieve and record DTCs. If same DTC is displayed and symptom is present, problem is current in diagnostic circuit; diagnose and repair DTC. Refer to DIAGNOSTIC TROUBLE CODE DEFINITIONS .
    NOTE: When the diagnostic system is switched from the normal mode to the check mode, all the DTC(s) and freeze frame data recorded in the normal mode will be erased. So before switching modes, always check the DTC(s) and freeze frame data, and note them down.
    NOTE: According to the DATA LIST displayed by the OBD II scan tool or hand-held tester, you can read the value of the switch, sensor, actuator and so on without parts removal. Turn the ignition switch ON. Read the DATA LIST. See Fig 3.
Fig 1: Inspecting DLC3 Condition
G00173738Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 2: Connecting Hand-Held Tester To DLC3
G00173737Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
Fig 3: Identifying Hand-Held Tester DATA LIST
G00173739Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
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