Engine Immobilizer System - Diagnostics: Pre-Check

1. Description

   ECM controls the function of immobilizer on this vehicle. Data of the immobilizer or DTC can be read form DLC3 of the vehicle. When a trouble occurs on immobilizer, check engine warning light does not light up but DTC inspection is performed.

   Therefore when there seems to be a trouble on immobilizer, use the LEXUS hand-held tester or SST to check and troubleshoot it.

   Fig 1: Connecting Hand-Held Tester To DLC3

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Check the DLC3.

   The vehicle's ECM uses ISO 9141-2 for communication. The terminal arrangement of DLC3 complies with SAE J1962 and matches the ISO 9141-2 format.

   Fig 2: Checking DLC3

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   TERMINAL CONNECTION SPECIFIED CONDITION
   
   

   Terminal No.	Connection / Voltage or Resistance	Condition
   4	Chassis Ground <-> Body Ground / 1 Ω or less	Always
   7	Bus oplus Line / Pulse generation	During communication
   16	Battery Positive <-> Body Ground / 9 ~ 14 V	Always

   HINT:

   If your display shows "UNABLE TO CONNECT TO VEHICLE" when you have connected the cable of the LEXUS hand-held tester to DLC3, turned the ignition switch ON and operated the hand-held tester, there is a problem on the vehicle side or tool side.

   • If communication is normal when connecting the tool to another vehicle, inspect DLC3 on the original vehicle.
   • If communication is still not possible when connecting the tool to another vehicle, the problem is probably in the tool itself. Consult the Service Department listed in the tool's instruction manual in that case.

1. Check the DTC using LEXUS hand-held tester.
   NOTE: Hand-held tester only: When the diagnosis system is switched from normal mode to check mode, it erases all DTCs and freezed frame data recorded in normal mode. So before switching modes, always check the DTCs and freezed frame data, and note them down. 
   1. Prepare the hand-held tester.
   2. Connect the hand-held tester to DLC3.
   3. Turn the ignition switch ON and push the hand-held tester main switch ON.
   4. Use the hand-held tester to check the DTCs and freezed frame data, note them down (For operating instructions, see the hand-held tester instruction book.).
   5. See DIAGNOSTIC TROUBLE CODE CHART to confirm the details of the DTCs.
2. Check the DTC (Using diagnosis check wire)
   1. Turn ignition switch ON, but do not start the engine.
   2. Using SST, connect between terminals 13 (TC) and 4(CG) of DLC3.
      1. SST 09843-18040
      Fig 3: Connecting Between Terminals TC And CG

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   3. Read the diagnostic trouble code from malfunction indicator lamp.

      HINT:

      • If a diagnostic trouble code is not output, check the TC terminal circuit (See DIAGNOSIS CIRCUIT ).
      • ECM controls the immobilizer function on this vehicle, DTC is out put with engine data.
      • As an example, the blinking patterns for codes; normal and 99 are shown in the charts.
      Fig 4: Example Of Codes: Normal And 99 Blinking Pattern (1 Of 2)

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      Fig 5: Example Of Codes: Normal And 99 Blinking Pattern (2 Of 2)

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   4. When DTC "99" is output, there is a trouble of immobilizer. Start troubleshooting referring to PROBLEM SYMPTOMS TABLE.
   5. After completing the check, disconnect terminals 13 (TC) and 4 (CG) and turn off the display.

   HINT:

   In the event of 2 or more malfunction codes, indication will begin from the smaller numbered code and continue in order to the larger.

3. Clear the DTC.

   The following operations will erase the DTCs and freeze frame data.

   1. Hand-Held Tester:

      Operating the LEXUS hand-held tester to erase the codes.

   2. Except Hand-Held Tester:

      Disconnecting the battery terminals or EFI fuse for 1 minutes or more.

HINT:

According to the DATA LIST displayed by the LEXUS hand-held tester, you can read the value of the switch, sensor, actuator and so on without parts removal. Reading the DATA LIST as a first step of troubleshooting is one of the method to shorten the labor time.

1. Connect the LEXUS hand-held tester to the DLC3.
2. Turn the ignition switch ON.
3. According to the display on tester, read the "DATA LIST".