Engine Control System - Diagnosis: 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 on board 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 powertrain 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 ).

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

   Fig 1: Identifying Check
   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   • 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 DIAGNOSTIC TROUBLE CODE CHART ).
   Fig 2: Connecting Hand-Held Tester Or OBD It Scan Tool To Data Link Connector 3
   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 deletion 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, and other data from the time the 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, P0172, P0174 and P0175) and misfire DTCs (P0300 to P0308).
   2. Fuel trim malfunction DTCs (P0171, P0172, P0174 and P0175).
   3. Misfire DTCs (P0300 to P0308).
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 Connector Terminal Of DLC3

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   Fig 4: Terminal Reference Chart

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   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.
   1. 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 CODED. For the OBD II scan tool, see its instruction manual.

   4. See DIAGNOSTIC TROUBLE CODE CHART  to confirm the details of the DTCs.
   Fig 5: Connecting OBD II Scan Tool Or Hand-Held Tester To DLC3
   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   NOTE: When simulating a symptom with the OBD II scan tool (excluding hand-held tester) to check the DTCs, use the normal mode. For DTCs 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. Clearing the DTCs using the OBD II scan tool or the hand-held 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 hand-held 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. Clearing the DTCs not using the OBD II scan tool or the hand-held tester.

   Remove the EFI or ECD No. 1 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.
   4. Turn the ignition switch ON.
   5. Change the ECM to check mode with the hand-held tester. Enter the following menus: DIAGNOSIS / ENHANCED OBD II / CHECK MODE. Make sure the MIL flashes as shown in the illustration.
      Fig 6: Connecting Hand-Held Tester To DLC3

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
      NOTE: All DTCs and freeze frame data recorded will be erased if:

      1. the hand-held tester is used to change the ECM from normal mode to check mode or vice-versa; or 2) during check mode, the ignition switch is turned from ON to ACC or OFF.
      Fig 7: Identifying MIL Flashes
      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   6. Start the engine. The MIL should turn off after the engine starts.
   7. Simulate the conditions of the malfunction described by the customer.
   8. After simulating the malfunction conditions, use the hand-held tester diagnosis selector to check the DTC, freeze frame data and other data.
   9. After checking the DTC, inspect the applicable circuit.
2. Clearing DTCs using the OBD II scan tool or the hand-held 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 hand-held 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. Clearing the DTCs without using the OBD II scan tool or the hand-held tester.

   Remove the EFI or ECD No. 1 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.

If any of the following code is recorded, the ECM enters fail-safe mode.

Fig 8: Fail-Safe Chart

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Hand-held tester only:

Inspect the vehicle's ECM using check mode. Intermittent problems are easier to detect when the ECM is in check mode with hand-held tester. In check mode, the ECM uses 1 trip detection logic, which has a higher sensitivity to malfunctions than normal mode (default), which uses 2 trip detection logic.

1. Clear the DTCs. (See step  2)
2. Set the check mode. (See step  3)
3. Perform a simulation test (See HOW TO PROCEED WITH TROUBLESHOOTING ).
4. Check the connector and terminal (See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE ).
5. Wiggle the harness and connector (See HOW TO USE THE DIAGNOSTIC CHART AND INSPECTION PROCEDURE ).

When the malfunction is not confirmed in the DTC check, troubleshooting should be carried out in all the possible circuits considered as causes of the problem. In many cases, by carrying out the basic engine check shown in the following flowchart, the location causing the problem can be found quickly and efficiently. Therefore, using this check is essential in the engine troubleshooting.

1. Is battery positive voltage 11 V or more when engine stopped? 
   1. NO: Charge or replace battery. 
   2. YES: Go to next step. 
2. Is engine cranked? 
   1. NO: Proceed to  ON-VEHICLE TESTING  and  STARTER RELAY TEST  , and continue to troubleshoot. 
   2. YES: Go to next step. 
3. Does engine start? 
   1. NO: Go to step   6 . 
   2. YES: Go to next step. 
4. Check air filter. 

   PREPARATION: 

   Remove the air filter.

   CHECK: 

   Visual check that the air filter is not excessively dirty or oily.

   1. NG: Repair or replace air filter. 
   2. OK: Go to next step. 
5. Check idle speed. 

   PREPARATION: 

   1. Warm up the engine to the normal operating temperature.
   2. Switch off all the accessories.
   3. Switch off the A/C.
   4. Shift the transmission into the N position.
   5. Connect the OBD II scan tool or hand-held tester to the DLC3 of the vehicle.

   CHECK 

   Use CURRENT DATA to check the idle speed.

   OK: 

   1. Idle speed: 650 to 750 RPM 
   1. NG: Proceed to problem symptoms table on  PROBLEM SYMPTOMS TABLE  . 
   2. OK: Go to next step. 
6. Check fuel pressure. 

   PREPARATION: 

   1. Be sure that enough fuel is in the tank.
   2. Connect the hand-held tester to the DLC3.
   3. Turn the ignition switch ON and push the hand-held tester main switch ON.
   4. Use the ACTIVE TEST mode to operate the fuel pump.
   5. Please refer to the hand-held tester operator's manual for further details.
   6. If you have no hand-held tester, connect the positive (+) and negative (-) leads from the battery to the fuel pump connector (See FUEL PUMP ).
   Fig 9: Checking Fuel Pressure
   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   CHECK: 

   Check that the pulsation damper screw rises up when the fuel pump operation (See FUEL PUMP ).

   HINT:

   At this time, you will hear a fuel flowing noise.

   1. NG: Proceed to page SF-7 and continue to troubleshoot. 
   2. OK: Go to next step. 
7. Check for spark. 

   PREPARATION: 

   1. Disconnect the ignition coil.
   2. Remove the spark plug.
   3. Install the spark plug to the ignition coil.
   4. Disconnect the injector connector.
   5. Ground the spark plug.
   Fig 10: Checking For Spark

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

   CHECK: 

   Check if spark occurs while the engine is being cranked.

   NOTE: To prevent excess fuel from being injected from the injectors during this test, don't crank the engine for more than 5 to 10 seconds at a time.
   1. NG: Proceed to  IGNITION SYSTEM  and continue to troubleshoot. 
   2. OK: Proceed to problem symptoms table on  PROBLEM SYMPTOMS TABLE  . 

HINT:

Using the hand-held tester DATA LIST allows switch, sensor, actuator and other item values to be read without removing any parts. Reading the DATA LIST early in troubleshooting is one way to shorten labor time.

1. Warm up the engine.
2. Turn the ignition switch OFF.
3. Connect the hand-held tester or the OBD II scan tool to the DLC3.
4. Turn the ignition switch ON.
5. Push the "ON" button of the hand-held tester.
6. Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DATA LIST.
7. According to the display on tester, read the "DATA LIST".

Fig 11: Diagnostic Chart (1 Of 3)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 12: Diagnostic Chart (2 Of 3)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 13: Diagnostic Chart (3 Of 3)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT:

Performing the ACTIVE TEST using the hand-held tester or the OBD II scan tool allows the relay, VSV, actuator and so on to operate without parts removal. Performing the ACTIVE TEST as a first step of troubleshooting is one method to shorten diagnostic time.

It is possible to display the DATA LIST during the ACTIVE TEST.

1. Warm up the engine.
2. Turn the ignition switch OFF.
3. Connect the hand-held tester or the OBD II scan tool to the DLC3.
4. Turn the ignition switch ON.
5. Push the "ON" button of the hand-held tester or the OBD II scan tool.
6. Enter the following menus: DIAGNOSIS / ENHANCED OBD II / ACTIVE TEST.
7. According to the display on tester, perform the "ACTIVE TEST".

Fig 14: Diagnostic Chart (Active Test)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

This reference list indicates the part names used in this manual along with their definitions.

Fig 16: Toyota/Lexus Reference Chart

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

HINT:

This table indicates ECM monitoring status for the items in the upper columns if the DTCs in each line on the left are being set.

As for the "X" mark, when the DTC on the left is stored, detection of the DTC in the upper column is not performed.

Fig 17: Monitor Detected Malfunction Chart (1 Of 6)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 18: Monitor Detected Malfunction Chart (2 Of 6)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 19: Monitor Detected Malfunction Chart (3 Of 6)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 20: Monitor Detected Malfunction Chart (4 Of 6)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 21: Monitor Detected Malfunction Chart (5 Of 6)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

Fig 22: Monitor Detected Malfunction Chart (6 Of 6)

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

INTRODUCTION 

The O2S TEST RESULT refers to the results of the engine control module (ECM) when it monitors the oxygen sensor (O2S), and it can be read using the hand-held tester or the generic OBD II scan tool. Based on this, you can find the O2S's conditions.

The ECM monitors the O2S in the various items. You can read the monitor result (TEST DATA) of each monitor item using the O2S TEST RESULT. However, the output value of the TEST DATA is the latest "snapshot" value that is taken after monitoring and therefore is not dynamic.

In this repair manual, the description of the O2S TEST RESULT (for O2S related DTCs) are written in a table.

This table consists of 5 items:

1. TEST ID (a code applied to each TEST DATA)
2. Description of TEST DATA
3. Conversion Factor (When Conversion Factor has a value written in the table, multiply the TEST DATA value appearing on the scan tool by the Conversion Factor value. The result will be the required value.)
4. Unit
5. Standard Value

If the TEST DATA value appearing on the scan tool is out of the standard value, the O2S is malfunctioning. If it is within the standard value, the O2S is functioning normally. However, if the value is on the borderline of the standard value, the O2S may malfunction very soon.

HOW TO READ O2S TEST RESULT USING HAND-HELD TESTER 

1. Connect the hand-held tester to the DLC3.
2. On the tester screen, select the following menus: DIAGNOSIS/CARB OBDII/O2S TEST RESULT. A list of the O2S equipped on the vehicle will be displayed.
   Fig 23: Diagnosis/CARB OBDII/O2S Test Result Display

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
3. Select the desired O2S and press ENTER. The following screen will appear.
4. Press HELP and * simultaneously. More information will appear.
5. Example:
   1. The hand-held tester displays "17" as a value of the "TIME $81" (see Fig 24).
   2. Find the Conversion Factor value of "TIME $81" in the O2S TEST RESULT chart below. 0.3906 is specified for $81 in this chart.
   3. Multiply "17" in step (1) by 0.3906 (Conversion Factor) in the step (2).
      1. 17 x 0.3906 = 6.6% 
   4. If the answer is within the standard value, the "TIME $81" can be confirmed to be normal.
   Fig 24: Test Data Screen

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

O2S TEST RESULT Chart 

HINT:

"MONITOR RESULT" indicates normal or malfunction of each component and system when judgment has done.

1. HOW TO READ DATA (using the hand-held tester)
   1. Connect the hand-held tester to the DLC3.
   2. Enter the following menus:

      "MONITOR RESULT" from "DIAGNOSIS / ENHANCED OBD II / MONITOR INFO / MONITOR RESULT" the Test ID will appear at the beginning of each line, following by INCMP, PASS or FAIL.

      Fig 26: Monitor Result Display

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      HINT:

      • INCMP: Stands for "incomplete" the diagnosis is incomplete.
      • PASS: The component or system is operating normally.
      • FAIL: A malfunction has been detected.
   3. Select a Test ID that you want from the list and press the "ENTER" button. You will see the following screen:
      • VAL (TEST VALUE) [Test Data] [Unit]
      • LMT (TEST LIMIT) [Test Limit] [Unit]
      • TLT [Test Limit Type]
      Fig 27: Thermostat Malfunction Display

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   4. By pressing the "HELP" button, you can see more information.

   HINT:

   • Monitor test results can be viewed in the MONITOR RESULT screen.
   • Monitor test results indicate the latest malfunction judgement result of this diagnostic.
   • TEST VALUE indicates the detection parameter value (Example: P0128 Thermostat Malfunction = Engine coolant temperature) at the time of malfunction (or normal) judgement is done.
   • TEST LIMIT indicates a threshold of malfunction judgement (Example: P0128 Thermostat Malfunction = 75°C (167°F)).
   • When the monitor runs, the monitored Parameter's VALUE is recorded. The value is then compared to the TEST LIMIT to determine if the result is PASS or FAIL.
   • By comparing the Parameter VALUE to the TEST LIMIT, it is possible to determine the degree of failure.
   • In rare cases, the monitor may have passed even with a DTC set and MIL illuminated. The monitor may have failed on a previous trip, and then passed on the most recent trip. This would indicated an intermittent problem may be the cause of the DTC.
   Fig 28: Information Display

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002