Section 5 (Engine Controls (2ZZ-GE) - Diagnostics): Pre-Check

1. Description
   • When troubleshooting On-Board Diagnostic (OBD II) vehicles, the vehicle must be connected to the OBD II scan tool (in compliance with SAE J1978) or the hand-held tester. Various data output from the vehicle's ECM can then be read.
   • OBD II regulations require that the vehicle's onboard computer illuminates the Malfunction Indicator Light (MIL) on the instrument panel when the computer detects a malfunction in: 1) the emission control system/components, or 2) the power train control components (which affect vehicle emissions), or 3) the computer. In addition, the applicable Diagnostic Trouble Codes (DTCs) prescribed by SAE J2012 are recorded in the ECM memory (See DIAGNOSTIC TROUBLE CODE CHART  ).
     Fig 1: Identifying Malfunction Indicator Light (MIL)

     Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   If the malfunction does not recur in 3 consecutive trips, the MIL goes off automatically but the DTCs remain recorded in the ECM memory.

   • To check the DTC, connect the hand-held tester or OBD II scan tool to the Data Link Connector 3 (DLC3) of the vehicle. The hand-held tester or OBD II scan tool also enables you to erase the DTC and check the freeze frame data and various forms of engine data (See the instruction manual for the OBD II scan tool or the hand-held tester). The DTC includes SAE controlled codes and manufacturer controlled codes. SAE controlled codes must be set according to the SAE, while manufacturer controlled codes can be set by a manufacturer with certain restrictions (See the DTC chart on DIAGNOSTIC TROUBLE CODE CHART  ).
     Fig 2: Connecting Hand-Held Tester To Data Link Connector (DLC3) Of Vehicle

     Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   • The diagnosis system operates in "normal mode" during normal vehicle use. In "normal mode", 2 trip detection logic* is used to ensure accurate detection of malfunctions. A "check mode" is also available to technicians as an option. In "check mode", 1 trip detection logic is used for simulating malfunction symptoms and increasing the system's ability to detect malfunctions, including intermittent malfunctions (hand-held tester only) (See step 3).
   • *2 trip detection logic:

     When a malfunction is first detected, the malfunction is temporarily stored in the ECM memory. This is known as 1st trip detection. If the ignition switch is turned OFF and then ON again, and the same malfunction is detected again, the MIL will illuminate. This is known as 2nd trip detection.

   • Freeze frame data:

     The freeze frame data records the engine conditions (fuel system, calculated load, engine coolant temperature, fuel trim, engine speed, vehicle speed, etc.) when a malfunction is detected. When troubleshooting, freeze frame data can help determining if the vehicle was running or stopped, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, as well as other data from the time when a malfunction occurred.

   Priorities for troubleshooting:

   When multiple DTCs occur, find out the order in which the DTCs should be inspected by checking the component's DTC chart. If no instructions are written in the DTC chart, check DTCs in the following order of priority:

   1. DTCs other than fuel trim malfunction DTCs (P0171 and P0172) and misfire DTCs (P0300 to P0304).
   2. Fuel trim malfunction DTCs (P0171 and P0172).
   3. Misfire DTCs (P0300 to P0304).
2. Check the DLC3.

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

   Fig 3: Identifying DLC3 Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   DLC3 TERMINALS REFERENCE
   
   

   Symbol	Name	Result
   (Terminal No.)	(Reference terminal)	(Condition)
   SIL	Bus "+" line	Pulse generation
   (7)	(5 - Signal ground)	(During transmission)
   CG	Chassis ground	1 Ω or less
   (4)	(Body ground)	(Always)
   SG	Signal ground	1 Ω or less
   (5)	(Body ground)	(Always)
   BAT	Battery positive	9 to 14 V
   (16)	(Body ground)	(Always)

   HINT:

   Connect the cable of the hand-held tester 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 exists in the vehicle side or the tester side.

   • If the communication is normal when the tool is connected to another vehicle, inspect the DLC3 on the original vehicle.
   • If the communication is still impossible when the tool is connected to another vehicle, the problem is probably in the tool itself, so consult the Service Department listed in the tool's instruction manual.
3. Inspect the battery voltage.

   Battery Voltage: 11 to 14 V 

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

4. Check the MIL.
   1. The MIL comes on when the ignition switch is turned ON and the engine is not running.

      HINT:

      If the MIL is not illuminated, troubleshoot the MIL circuit (See MIL Circuit  ).

   2. When the engine is started, the MIL should not illuminate. If the lamp remains on, the diagnosis system has detected a malfunction or abnormality in the system.

1. Checking DTCs using the OBD II scan tool or hand-held tester.
   1. Connect the OBD II scan tool or the hand-held tester to DLC3.
   2. Turn the ignition switch ON.
   3. Use the OBD II scan tool or the hand-held tester to check the DTCs and freeze frame data and then write them down.

      For the hand-held tester, enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES. For the OBD II scan tool, see its instruction manual.

      Fig 4: Connecting Hand-Held Tester To Data Link Connector (DLC3) Of Vehicle

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   4. See PRE-CHECK  to confirm the details of the DTCs.
   NOTE: When simulating a symptom with the OBD II scan tool (excluding hand-held tester) to check the DTCs, use the normal mode. For DTC chart subject to "2 trip detection logic", perform either of the following actions.

   • Check the pending fault code:

     For the hand-held tester, enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / PENDING CODES.

   • Turn the ignition switch OFF after the symptom is simulated once. Then repeat the simulation process again. When the problem has been simulated twice, the MIL comes on and the DTCs are recorded in the ECM.
   • Check the pending fault code using the Continuous Test Results function (Mode 7 for SAE J1979) on the OBD II scan tool.
2. Clear the DTCs using the OBD II scan tool or the handheld tester.
   1. Connect the OBD II scan tool or the hand-held tester to the DLC3.
   2. Turn the ignition switch ON.
   3. Erase DTCs and freeze frame data with the OBD II scan tool (complying with SAE J1978) or the handheld tester For the hand-held tester: 1) enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CLEAR CODES; and 2) press YES. For the OBD II scan tool, see its instruction manual.
3. Clear the DTCs not using the OBD II scan tool or the hand-held tester.

   Remove the EFI and ETCS fuses from the engine room J/B for more than 60 seconds, or disconnect the battery terminal for more than 60 seconds.

   After disconnecting the battery terminal, perform the "INITIALIZE procedure.

HINT:

Hand-held tester only:

Check mode has a higher sensitivity to detect malfunctions and can detect malfunctions that normal mode cannot detect. Check mode can also detect all the malfunctions that normal mode can detect.

1. Follow these steps when preparing to use the hand-held tester check mode.
   1. Make sure that the items below are true:
      • Battery positive voltage 11 V or more
      • Throttle valve fully closed
      • Transmission in the P or N position
      • A/C switched OFF
   2. Turn the ignition switch OFF.
   3. Connect the hand-held tester to the DLC3.
      Fig 5: Connecting Hand-Held Tester To Data Link Connector (DLC3) Of Vehicle

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   4. Turn the ignition switch ON.
   5. Change the ECM to check mode with the handheld tester. Enter the following menus: DIAGNOSIS / ENHANCED OBD II / CHECK MODE. Make sure the MIL flashes as shown in the illustration.
      Fig 6: Identifying MIL Flashes

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002