Engine Control System Self-Diagnostics: Diagnosis Toyota Prius I рестайлинг

MALFUNCTION INDICATOR LIGHT INSPECTION

Note. Malfunction Indicator Light (MIL) may also be referred to as CHECK ENGINE light. Inspect MIL to ensure it is operational and will come on if a Diagnostic Trouble Code (DTC) is set or problem exists in the Hybrid Vehicle (HV) control system.

1. Turn ignition on. Check that MIL comes on and remains on. MIL is located on instrument cluster at center of instrument panel and is displayed as an engine icon. If MIL comes on and remains on, go to next step. If MIL does not come on, check bulb circuit on instrument cluster and Green/Red wire and electrical connectors between MIL and Engine Control Module (ECM). See WIRING DIAGRAMS article. ECM is located behind the glove box. see scheme 3
2. Start engine and ensure MIL goes off. If MIL goes off, no malfunction is detected at this time. If MIL remains on or blinks with engine running, a malfunction is detected. Proceed to «TESTING PROCEDURE»(ref-97394-S42157890692001050400000).

TESTING PROCEDURE

To ensure correct diagnosis and repair, testing should be done in the following sequence

1. Record Customer Complaint Ensure all customer complaints or observations are recorded. Test drive vehicle with customer when necessary for malfunction verification.
2. Retrieve Diagnostic Trouble Codes Using Toyota hand-held tester or scan tool, retrieve Diagnostic Trouble Codes ( DTC) from Engine Control Module (ECM) and record any freeze frame data (if applicable). See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-97394-S21986087992001050400000) .
3. Clear Diagnostic Trouble Codes Using Toyota hand-held tester or scan tool, clear DTCs and freeze frame data from ECM. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-97394-S14249235912001050400000) .
4. Visual Inspection Inspect all electrical connectors and wiring for suspected circuit or component. Ensure all electrical connections are clean and tight.
5. Confirm Symptoms & Diagnostic Trouble Codes Perform road test. Determine if original symptoms still exists. Using scan tool or Toyota hand-held tester, retrieve DTCs from ECM. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-97394-S21986087992001050400000) .
6. Diagnose & Repair Diagnostic Trouble Codes Perform appropriate DTC test listed under DIAGNOSTIC TESTS as necessary. For DTC descriptions, see «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-97394-S41560385102001050400000) table under DIAGNOSTIC TROUBLE CODE DEFINITIONS. If no DTCs are present and a no start condition exists, proceed to appropriate BASIC DIAGNOSTIC PROCEDURES article. If no DTCs are present and a driveability condition exists, proceed to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, ENGINE STALLS, etc.).
7. Verification Procedure After repairs have been completed, clear all DTCs from ECM. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-97394-S14249235912001050400000) . Perform road test. Ensure no DTCs exist and all symptoms and/or complaints have been repaired.

RETRIEVING DIAGNOSTIC TROUBLE CODES

Note. Before retrieving Diagnostic Trouble Codes (DTC), ensure TESTING PROCEDURE is followed.

Note. Diagnostic Trouble Codes (DTC) may be retrieved using Toyota hand-held tester or On-Board Diagnostic (OBD-II) scan tool that complies with SAE standard J-1978. Toyota hand-held tester or OBD-II scan tool may be operated in NORMAL mode when retrieving DTCs. Only Toyota hand-held tester may be used in CHECK mode when retrieving DTCs.

NORMAL mode is used to retrieve DTCs from Engine Control Module (ECM). CHECK mode is used to check for DTCs when operating vehicle to simulate conditions during which DTC was set. CHECK mode contains a higher sensing ability to detect malfunctions. CHECK mode helps determine malfunctions caused by poor electrical connections or intermittent problems which are difficult to determine using NORMAL mode.

Note. If using Toyota hand-held tester, when ignition switch is turned from ON to ACC or OFF position during CHECK mode, hand-held tester is switched from NORMAL mode to CHECK mode or from CHECK MODE to NORMAL mode, all DTCs and freeze frame data will be erased from ECM. DO NOT switch modes until all DTCs and freeze frame data have been recorded.

NORMAL Mode Diagnostic Trouble Code Retrieval

1. Connect Toyota hand-held tester or scan tool to Data Link Connector (DLC) No. 3. see scheme 2 Turn ignition on with engine off. Turn hand-held tester or scan tool on. Using hand-held tester or scan tool manufacturer's instructions, check for DTCs and freeze frame data.
2. If hand-held tester or scan tool does not display UNABLE TO CONNECT TO VEHICLE, go to next step. If hand-held tester or scan tool displays UNABLE TO CONNECT TO VEHICLE, check DLC No. 3. See «DATA LINK CONNECTOR NO. 3 INSPECTION»(ref-97394-S17849442532001050400000) under SCAN TOOL PROBLEMS.
3. Record any DTCs and freeze frame data displayed for system diagnosis. If driveability problem exists and no DTCs are present, go to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom. If no DTCs are present and no driveability problem exists but Malfunction Indicator Light (MIL) is illuminated, a problem may exist in the Hybrid Vehicle (HV) control system. Consult authorized dealer for diagnosis of HV control system.
4. If any DTCs are present, perform appropriate DTC test listed under DIAGNOSTIC TESTS. For DTC descriptions, see «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-97394-S41560385102001050400000) table under DIAGNOSTIC TROUBLE CODE DEFINITIONS. For information on freeze frame data, see «FREEZE FRAME DATA»(ref-97394-S17214907182001050400000). For information on two-trip detection logic DTCs, see «TWO-TRIP DETECTION LOGIC»(ref-97394-S33185699112001050400000).
5. After repairs for DTC have been completed, DTC must be cleared from ECM. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-97394-S14249235912001050400000). Road test vehicle to ensure all symptoms and/or complaints have been repaired.

CHECK Mode Diagnostic Trouble Code Retrieval (Toyota Hand-Held Tester Only)

Note. If using Toyota hand-held tester, if ignition switch is turned from ON to ACC or OFF position during CHECK mode, all DTCs and freeze frame data will be erased from ECM. DO NOT switch from CHECK mode to NORMAL mode until all DTCs and freeze frame data are recorded.

1. Ensure vehicle battery is fully charged. Apply parking brake. Place transaxle in Park or Neutral. Ensure A/C and ignition are off. Check that throttle valve is fully closed. Connect hand-held tester to Data Link Connector (DLC) No. 3. see scheme 2 Turn ignition on and then turn hand-held tester on.
2. Switch hand-held tester from NORMAL mode to CHECK mode. Ensure Malfunction Indicator Light (MIL) on instrument cluster flashes to indicate CHECK mode operation. Start engine. If no DTCs exist, MIL will turn off. Try to simulate conditions of driveability complaint described by customer.
3. Record any DTCs and freeze frame data displayed for system diagnosis. If driveability problem exists and no DTCs are present, go to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom. If no DTCs are present and no driveability problem exists but MIL is illuminated, a problem may exist in the Hybrid Vehicle (HV) control system. Consult authorized dealer for diagnosis of HV control system.
4. If any DTCs are present, perform appropriate DTC test listed under DIAGNOSTIC TESTS. For DTC description, see «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-97394-S41560385102001050400000) table under DIAGNOSTIC TROUBLE CODE DEFINITIONS. For information on freeze frame data, see «FREEZE FRAME DATA»(ref-97394-S17214907182001050400000). For information on two-trip detection logic codes, see «TWO-TRIP DETECTION LOGIC»(ref-97394-S33185699112001050400000).
5. After repairs for DTC have been completed, DTC must be cleared from ECM. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-97394-S14249235912001050400000). Road test vehicle to ensure all symptoms and/or complaints have been repaired.

CLEARING DIAGNOSTIC TROUBLE CODES

1. After repairs for Diagnostic Trouble Codes (DTC) have been completed, DTCs and freeze frame data should be cleared from Engine Control Module (ECM) memory. Using scan tool or Toyota hand-held tester, follow the manufacturer's instructions and clear DTCs and freeze frame data from ECM.
2. DTCs and freeze frame data may also be cleared by removing EFI fuse. EFI fuse is a 15-amp fuse located in fuse/relay box at driver's side front corner of engine compartment. DTCs and freeze frame data may also be cleared by disconnecting negative battery cable. However, other various memory functions such as the clock, radio, alarm, seats, etc. will be cleared and must be reset.

TEST DRIVE CONFIRMATION

1. On certain Diagnostic Trouble Codes (DTC), once DTC has been cleared from Engine Control Module (ECM) memory, a test drive confirmation test can be performed to verify repairs are made and that DTC does not reset. Test drive confirmation test will duplicate conditions required to set specified DTCs.
2. Test drive confirmation test lists the procedure to be performed to check that DTC does not reset. Test drive confirmation tests apply only to specific DTCs. Test drive confirmation test will be included within proper DTC test under DIAGNOSTIC TESTS.

DATA LINK CONNECTOR NO. 3 INSPECTION

1. If Toyota hand-held tester or scan tool displays UNABLE TO CONNECT TO VEHICLE when hand-held tester or scan tool is connected to Data Link Connector (DLC) No. 3, try hand-held tester or scan tool on another vehicle. If hand-held tester or scan tool operates on another vehicle, go to next step. If hand-held tester or scan tool does not operate on another vehicle, problem is probably with hand-held tester or scan tool.
2. Check DLC No. 3 for loose or damaged terminals. Ensure DLC No. 3 terminals are in correct position in connector. See WIRING DIAGRAMS article. For full wiring diagram of DLC No. 3, it may be necessary to see DATA LINK CONNECTORS article in WIRING DIAGRAMS. If connector and terminals are okay, go to next step. If connector or terminals are defective, repair as necessary.
3. Check voltage and resistance between ground and specified terminal on DLC No. 3. See «DATA LINK CONNECTOR NO. 3 VOLTAGE & RESISTANCE SPECIFICATIONS»(ref-97394-S38657804412001050400000) table. (Scheme 297) If voltage or resistance readings are not within specification, check wiring circuit. See WIRING DIAGRAMS article.

DATA LINK CONNECTOR NO. 3 VOLTAGE & RESISTANCE SPECIFICATIONS

Scheme 297

INSPECTION MODE

Note. The engine is shut off when engine is at normal operating temperature and battery is fully charged and A/C is not turned on. It is necessary to put transit in inspection mode so engine will run continuously.

To put transit in inspection mode, perform the following steps within 60 seconds

1. Ensure ignition is off and then turn ignition on.
2. Ensure transaxle is in Park and then fully depress accelerator pedal 2 times.
3. Place transaxle in Neutral and then fully depress accelerator pedal 2 times.
4. Place transaxle back in Park and then fully depress accelerator pedal 2 times.
5. Check that master warning light on instrument cluster at center of instrument panel is flashing to indicate inspection mode operation. (Scheme 298) Master warning light may also be referred to as hybrid system error warning light. Turn ignition switch to START position to start engine. Engine will now start and run continuously.

Scheme 298

DIAGNOSTIC TROUBLE CODE DEFINITIONS

DIAGNOSTIC TROUBLE CODE DEFINITIONS

DIAGNOSTIC TESTS

Note. Before performing any diagnostic test, see SELF-DIAGNOSTIC SYSTEM for diagnostic system functions and system diagnostic procedures. Also check for any related Technical Service Bulletins (TSBs).

Note. When performing diagnostic tests, it may be necessary to put transit in inspection mode so that the engine will run continuously. See INSPECTION MODE .

Note. When performing diagnostic tests, it may be necessary to identify Engine Control Module (ECM) and Hybrid Vehicle Electronic Control Unit (HV ECU) electrical connector terminals which are referenced to in testing procedure. (Scheme 299)and (Scheme 300).

Scheme 299

Scheme 300

Diagnosis & Repair

1. Connect Toyota hand-held tester or scan tool to Data Link Connector (DLC) No. 3. see scheme 2 Turn ignition on and then turn hand-held tester or scan tool on. Start engine and allow engine to idle. Using hand-held tester or scan tool, monitor MAF meter air flow rate. If MAF meter air flow rate is 0.0 gm/sec., go to next step. If MAF meter air flow rate is 271 gm/sec. or more, go to step 5.
2. Turn ignition off. Disconnect electrical connector at MAF meter. MAF meter is bolted to upper cap on air cleaner assembly and contains a Black 5-pin electrical connector. Turn ignition on. Using voltmeter, check voltage between ground and terminal No. 1 (Black wire) on MAF meter electrical connector. (Scheme 301) If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, repair open in Black wire between EFI main relay and MAF meter. See WIRING DIAGRAMS article. EFI main relay may also be referred to as EFI relay. EFI main relay is located in fuse/relay box at driver's side front corner of engine compartment.
3. Turn ignition off. Reinstall electrical connector at MAF meter. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Ensure A/C switch is in OFF position shift lever is in Park. Start engine and allow engine to idle. Using voltmeter, check voltage between body ground and terminal No. 10 (Green wire) at ECM electrical connector E8. (Scheme 299) This is the VG terminal on ECM. Voltage should be 1.1-1.5 volts. If voltage is not within specification, go to next step. If voltage is within specification, replace ECM.
4. Check for open and short in Green wire and electrical connectors between MAF meter and ECM. See WIRING DIAGRAMS article. If wiring harness and electrical connectors are okay, replace MAF meter. If wiring harness or electrical connector is defective, repair as necessary.
5. Turn ignition off. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Using ohmmeter, check resistance between body ground and terminal No. 19 (Red wire) at ECM electrical connector E8. (Scheme 299) This is the EVG terminal on ECM. If resistance is one ohm or less, go to next step. If resistance is greater than one ohm, replace ECM.
6. Check for open in wiring harness and electrical connectors between MAF meter and ECM. See WIRING DIAGRAMS article. If wiring harness and electrical connectors are okay, replace MAF meter. If wiring harness or electrical connector is defective, repair as necessary.

Scheme 301

Using Toyota hand-held tester or scan tool, check for any other DTCs. If other DTCs exists, diagnose and repair those DTCs first and then retest. If only DTC P0101 exists, replace MAF meter. MAF meter is bolted to upper cap on air cleaner assembly and contains a Black 5-pin electrical connector.

1. Connect Toyota hand-held tester or scan tool to Data Link Connector (DLC) No. 3. see scheme 2 Turn ignition on and then turn hand-held tester or scan tool on.
2. Using hand-held tester or scan tool, read engine coolant temperature for ECT sensor. If displayed engine coolant temperature is -40°F (-40°C), go to next step. If displayed engine coolant temperature is 284°F (140°C) or more, go to step 8. If displayed engine coolant temperature is same as actual engine coolant temperature, problem is intermittent. Check for defective connections or intermittent problem in wiring between ECT sensor and ECM. ECT sensor is located on flywheel end of cylinder head and contains a Dark Gray 2-pin electrical connector with White and Brown wires. ECM is located behind glove box. see scheme 3
3. Turn ignition off. Disconnect electrical connector at ECT sensor. ECT sensor is located on flywheel end of cylinder head and contains a Dark Gray 2-pin electrical connector with White and Brown wires. Connect jumper wire between both terminals on electrical connector for ECT sensor. Turn ignition on.
4. Using hand-held tester or scan tool, read engine coolant temperature for ECT sensor. If displayed engine coolant temperature is less than 284°F (140°C), go to next step. If displayed engine coolant temperature is 284°F (140°C) or more, check for defective electrical connections at ECT sensor and electrical connector. If electrical connections are defective, repair as necessary. If electrical connections are okay, replace ECT sensor. Manufacturer states that converter and inverter assembly must be removed for servicing of ECT sensor. The converter and inverter assembly are involved with the high-voltage system used on this vehicle and service procedure should only be performed by authorized dealer.
5. Turn ignition off. Remove jumper wire. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Ensure electrical connectors at ECM are securely installed so all terminals in electrical connectors are contacting terminals in ECM.
6. Ensure electrical connector at ECT sensor is still disconnected. Connect jumper wire between terminals No. 14 (White wire) and No. 18 (Brown wire) at ECM electrical connector E8 with all electrical connectors installed on ECM. (Scheme 299) This is the THW and E2 terminals on ECM.
7. Turn ignition on. Using hand-held tester or scan tool, read engine coolant temperature for ECT sensor. If displayed engine coolant temperature is 284°F (140°C) or more, repair open Brown wire or White wire between ECT sensor and ECM. See WIRING DIAGRAMS article. If displayed engine coolant temperature is not 284°F (140°C) or more, replace ECM.
8. Turn ignition off. Disconnect electrical connector at ECT sensor. ECT sensor is located on flywheel end of cylinder head and contains a Dark Gray 2-pin electrical connector with White and Brown wires. Turn ignition on.
9. Using hand-held tester or scan tool, read engine coolant temperature for ECT sensor. If displayed engine coolant temperature is not -40°F (-40°C), go to next step. If displayed engine coolant temperature is -40°F (-40°C), replace ECT sensor. Manufacturer states that converter and inverter assembly must be removed for servicing of ECT sensor. The converter and inverter assembly are involved with the high-voltage system used on this vehicle and service procedure should only be performed by authorized dealer.
10. Turn ignition off. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Disconnect ECM electrical connector E8. (Scheme 299) Ensure electrical connector is still disconnected at ECT sensor.
11. Turn ignition on. Using hand-held tester or scan tool, read engine coolant temperature for ECT sensor. If displayed engine coolant temperature is -40°F (-40°C), repair short in wiring harness and electrical connectors between ECT sensor and ECM. See WIRING DIAGRAMS article. If displayed engine coolant temperature is not -40°F (-40°C), replace ECM.

1. Using Toyota hand-held tester or scan tool, check for any other DTCs. If only DTC P0116 exists, go to next step. If other DTCs exist, diagnose and repair those DTCs first and then retest.
2. Remove and inspect cooling system thermostat for damage and proper operation. Thermostat is located behind thermostat housing which is located just below the intake manifold.
3. If thermostat is defective, replace thermostat. Ensure proper cooling system bleeding procedure is performed when filling cooling system. See COOLING SYSTEM BLEEDING under COOLING SYSTEM in REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article. If thermostat is okay, replace ECT sensor. Manufacturer states that converter and inverter assembly must be removed for servicing of ECT sensor. The converter and inverter assembly are involved with the high-voltage system used on this vehicle and service procedure should only be performed by authorized dealer.

1. If using Toyota hand-held tester, go to next step. If Toyota hand-held tester is not available, go to step 4.
2. Connect hand-held tester to Data Link Connector (DLC) No. 3. see scheme 2 Turn ignition on and then turn hand-held tester on.
3. Using hand-held tester, monitor throttle valve opening by reading THROTTLE POS (displayed as a percentage) and THROTTLE POS#2 (displayed as a voltage) with accelerator pedal released and with accelerator pedal depressed. THROTTLE POS is the VTA circuit and THROTTLE POS#2 is the VTA2 circuit. With accelerator pedal released, THROTTLE POS should be 64-96 percent and THROTTLE POS#2 should be 4.6-5.1 volts. With accelerator pedal depressed, THROTTLE POS should be 8-20 percent and THROTTLE POS#2 should be 2.0-2.9 volts. If throttle valve opening readings are not within specification, go to next step. If throttle valve opening readings are within specification, replace ECM. ECM is located behind glove box. see scheme 3
4. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3
5. Turn ignition on. Using voltmeter, check voltage between terminals No. 2 (Yellow/Red wire) and No. 18 (Brown wire) at ECM electrical connector E8. (Scheme 299) This is the VC and E2 terminals on ECM. Voltage should be 4.5-5.5 volts. If voltage is specification, go to next step. If voltage is not within specification, replace ECM.
6. Ensure ignition is still on. Using voltmeter, check voltage between terminals No. 18 (Brown wire) and No. 23 (Pink wire) at ECM electrical connector E8 with accelerator pedal released and with accelerator pedal depressed. (Scheme 299) This is the E2 and VTA terminals on ECM. Also, check voltage between terminals No. 18 (Brown wire) and No. 21 (Blue wire) at ECM electrical connector E8 with accelerator pedal released and with accelerator pedal depressed. This is the E2 and VTA2 terminals on ECM. Ensure voltage is within specification. See «TP SENSOR VOLTAGE SPECIFICATIONS AT ECM»(ref-97394-S15585916052001042700000) table. If any voltage reading is not within specification, go to next step. If all voltage readings are within specification, replace ECM. TP SENSOR VOLTAGE SPECIFICATIONS AT ECM Accelerator Pedal Position & Terminals Volts Accelerator Pedal Released VTA & E2.4-1.0 VTA2 & E2 2.0-2.9 Accelerator Pedal Depressed VTA & E2 3.2-4.8 VTA2 & E2 4.6-5.1
7. Turn ignition off. Check TP sensor. See THROTTLE BODY under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If TP sensor is okay, go to next step. If TP sensor is defective, replace TP sensor. See THROTTLE BODY under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article.
8. Check for open and short in wiring harness and electrical connectors between TP sensor and ECM. See WIRING DIAGRAMS article. If wiring harness or electrical connector is defective, repair as necessary.

Using Toyota hand-held tester or scan tool, check for any other DTCs. If other DTCs exists, diagnose and repair those DTCs first and then retest. If only DTC P0121 exists, replace TP sensor. See THROTTLE BODY under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article.

1. Test drive confirmation may be performed to operate vehicle under conditions which may cause DTC to be set. If using Toyota hand-held tester, go to next step. If Toyota hand-held tester is not available, go to step 4.
2. Connect hand-held tester to Data Link Connector (DLC) No. 3. see scheme 2 Switch hand-held tester from NORMAL mode to CHECK mode. Go to next step.
3. Start engine and allow engine to idle for at least 30 seconds. Drive vehicle at a constant speed for at least 36 seconds. Check operation of Malfunction Indicator Light (MIL). If MIL illuminates, malfunction exists and DTC is set. If MIL does not illuminate, malfunction does not exist.
4. Start engine and allow engine to idle for at least 30 seconds. Drive vehicle at a constant speed for at least 36 seconds. Turn ignition off.
5. Start engine and allow engine to idle for at least 30 seconds. Drive vehicle at a constant speed for at least 36 seconds. Check operation of Malfunction Indicator Light (MIL). If MIL illuminates, malfunction exists and DTC is set. If MIL does not illuminate, malfunction does not exist.

1. Using Toyota hand-held tester or scan tool, check for any other DTCs. If only DTC P0125 exists, go to next step. If other DTCs exist, diagnose and repair those DTCs first and retest.
2. With Toyota hand-held tester or scan tool still connected to DLC No. 3, start engine and warm engine to normal operating temperature. Using hand-held tester or scan tool, monitor heated oxygen sensor No. 1 output voltage while suddenly accelerating engine to 4000 RPM for 3 consecutive times. Heated oxygen sensor No. 1 should indicate a rich condition by displaying output voltage of.45 volt or more at least once. If rich condition is not indicated by heated oxygen sensor No. 1 at least once, go to next step. If a rich condition is indicated by heated oxygen sensor No. 1 at least once, go to step 9.
3. Check for open and short in wiring harness and electrical connectors between heated oxygen sensor No. 1 and ECM. See WIRING DIAGRAMS article. Heated oxygen sensor No. 1 is located on exhaust pipe in front of catalytic converter. ECM is located behind glove box. see scheme 3 If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector is defective, repair as necessary.
4. Using hand-held tester or scan tool, check if a misfire has occurred by monitoring DTCs and DATA LIST. If misfire has not occurred, go to next step. If a misfire has occurred, perform «DTC P0300: RANDOM MISFIRE DETECTED»(ref-97394-S30478329162001050400000) or «DTCS P0301-P0304: CYLINDERS NO. 1-4 MISFIRE DETECTED»(ref-97394-S03856619492001050400000).
5. Ensure engine oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem does not exist, go to next step. If problem exists, repair as necessary.
6. Check fuel pressure. See FUEL PRESSURE under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4-CYLINDER article. Fuel pressure should be 44-50 psi (3.1-3.5 kg/cm 2 ) with engine idling and should remain at least 21 psi (1.5 kg/cm 2 ) for a minimum of 5 minutes after engine is shut off. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, repair fuel system as necessary.
7. Check operation of fuel injectors. See FUEL CONTROL under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. Fuel injector volume should be 36-46 cc (2.1-2.8 cu. in.) within 15 seconds and difference in volume between each fuel injector should be less than 10 cc (.6 cu. in.). Fuel injectors should not leak more than one drop every 12 minutes. If fuel injectors are okay, go to next step. If fuel injectors are defective, replace fuel injectors as necessary.
8. Check exhaust system for leaks. If no exhaust leak exists, replace heated oxygen sensor No. 1. If exhaust leak exists, repair exhaust system as necessary.
9. Using Toyota hand-held tester or scan tool, clear DTCs from ECM. Perform test drive confirmation and then go to next step. See «TEST DRIVE CONFIRMATION»(ref-97394-S37803382312001052100000).
10. Recheck for DTCs. If DTC P0125 does not exist, go to next step. If DTC P0125 exists, replace ECM. ECM is located behind glove box. ECM is located behind glove box. see scheme 3
11. Verify if vehicle ran out of fuel. If vehicle ran out of fuel, DTC P0125 was caused by the vehicle running out of fuel. If vehicle did not run out of fuel, problem is intermittent. Check for defective connections or intermittent problem in wiring. ECM is located behind glove box. see scheme 3

1. Remove and inspect cooling system thermostat for damage and proper operation. Thermostat is located behind thermostat housing which is located just below the intake manifold.
2. If thermostat is okay, ensure proper cooling system bleeding procedure is performed when filling cooling system. See COOLING SYSTEM BLEEDING under COOLING SYSTEM in REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article. Go to next step. If thermostat is defective, replace thermostat as necessary and retest system. Ensure proper cooling system bleeding procedure is performed when filling cooling system. See COOLING SYSTEM BLEEDING under COOLING SYSTEM in REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article.
3. Using Toyota hand-held tester or scan tool, check for any other DTCs. If other DTCs exist, diagnose and repair those DTCs first and retest. If only DTC P0128 exists, replace ECM. ECM is located behind glove box. see scheme 3

1. Test drive confirmation may be performed to operate vehicle under conditions which may cause DTC to be set. If using Toyota hand-held tester, go to next step. If Toyota hand-held tester is not available, go to step 4.
2. Connect hand-held tester to Data Link Connector (DLC) No. 3. see scheme 2 Switch hand-held tester from NORMAL mode to CHECK mode. Go to next step.
3. Start engine and allow engine to idle for at least 30 seconds. Drive vehicle at a constant speed for at least 36 seconds. Check operation of Malfunction Indicator Light (MIL). If MIL illuminates, malfunction exists and DTC is set. If MIL does not illuminate, malfunction does not exist.
4. Start engine and allow engine to idle for at least 30 seconds. Drive vehicle at a constant speed for at least 36 seconds. Turn ignition off.
5. Start engine and allow engine to idle for at least 30 seconds. Drive vehicle at a constant speed for at least 36 seconds. Check operation of Malfunction Indicator Light (MIL). If MIL illuminates, malfunction exists and DTC is set. If MIL does not illuminate, malfunction does not exist.

1. Using Toyota hand-held tester or scan tool, check for any other DTCs. If only DTC P0130 exists, go to next step. If other DTCs exist, diagnose and repair those DTCs first and retest.
2. With hand-held tester or scan tool still connected to DLC No. 3, start engine and increase engine speed to 2500 RPM for approximately 90 seconds and then allow engine to idle. Using hand-held tester or scan tool, monitor heated oxygen senor No. 1 output voltage. Heated oxygen senor No. 1 output voltage should alternate repeatedly between less than.42 volt and more than.48 volt. If output voltage is not within specification, go to next step. If output voltage is as within specification, go to step 7.
3. Check for open and short in wiring harness and electrical connectors between heated oxygen sensor No. 1 and ECM. See WIRING DIAGRAMS article. Heated oxygen sensor No. 1 is located on exhaust pipe in front of catalytic converter. ECM is located behind glove box. see scheme 3 If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector is defective, repair as necessary.
4. Ensure engine oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem does not exist, go to next step. If problem exists, repair as necessary.
5. Check fuel pressure. See FUEL PRESSURE under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4-CYLINDER article. Fuel pressure should be 44-50 psi (3.1-3.5 kg/cm 2 ) with engine idling and should remain at least 21 psi (1.5 kg/cm 2 ) for a minimum of 5 minutes after engine is shut off. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, repair fuel system as necessary.
6. Check operation of fuel injectors. See FUEL CONTROL under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. Fuel injector volume should be 36-46 cc (2.1-2.8 cu. in.) within 15 seconds and difference in volume between each fuel injector should be less than 10 cc (.6 cu. in.). Fuel injectors should not leak more than one drop every 12 minutes. If fuel injectors are okay, replace heated oxygen sensor No. 1. If fuel injectors are defective, replace fuel injectors as necessary.
7. Using Toyota hand-held tester or scan tool, clear DTCs from ECM. Perform test drive confirmation, then go to next step. See «TEST DRIVE CONFIRMATION»(ref-97394-S12815964782001051100000).
8. Recheck for DTCs. If DTC P0130 does not exist, replace ECM. ECM is located behind glove box. ECM is located behind glove box. see scheme 3 If DTC P0130 exists, problem is intermittent. Check for defective connections or intermittent problem in wiring between heated oxygen sensor No. 1 and electrical connectors. ECM is located behind glove box. see scheme 3

1. Test drive confirmation may be performed to operate vehicle under conditions which may cause DTC to be set. If using Toyota hand-held tester, go to next step. If Toyota hand-held tester is not available, go to step 4.
2. Connect hand-held tester to Data Link Connector (DLC) No. 3. see scheme 2 Switch hand-held tester from NORMAL mode to CHECK mode.
3. Start engine and allow engine to idle for at least 30 seconds. Drive vehicle at a constant speed for at least 36 seconds. Check operation of Malfunction Indicator Light (MIL). If MIL illuminates, malfunction exists and DTC is set. If MIL does not illuminate, malfunction does not exist.
4. Start engine and allow engine to idle for at least 30 seconds. Drive vehicle at a constant speed for at least 36 seconds. Turn ignition off.
5. Start engine and allow engine to idle for at least 30 seconds. Drive vehicle at a constant speed for at least 36 seconds. Check operation of Malfunction Indicator Light (MIL). If MIL illuminates, malfunction exists and DTC is set. If MIL does not illuminate, malfunction does not exist.

1. Using Toyota hand-held tester or scan tool, check for any other DTCs. If only DTC P0133 exists, go to next step. If other DTCs exist, diagnose and repair those DTCs first and retest.
2. With hand-held tester or scan tool still connected to DLC No. 3, start engine and increase engine speed to 2500 RPM for approximately 90 seconds and then allow engine to idle. Using hand-held tester or scan tool, monitor heated oxygen senor No. 1 output voltage. Heated oxygen senor No. 1 output voltage should alternate repeatedly between less than.42 volt and more than.48 volt. If output voltage is not within specification, go to next step. If output voltage is within specification, go to step 7.
3. Check for open and short in wiring harness and electrical connectors between heated oxygen sensor No. 1 and ECM. See WIRING DIAGRAMS article. Heated oxygen sensor No. 1 is located on exhaust pipe in front of catalytic converter. ECM is located behind glove box. see scheme 3 If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector is defective, repair as necessary.
4. Ensure engine oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem does not exist, go to next step. If problem exists, repair as necessary.
5. Check fuel pressure. See FUEL PRESSURE under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4-CYLINDER article. Fuel pressure should be 44-50 psi (3.1-3.5 kg/cm 2 ) with engine idling and should remain at least 21 psi (1.5 kg/cm 2 ) for a minimum of 5 minutes after engine is shut off. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, repair fuel system as necessary.
6. Check operation of fuel injectors. See FUEL CONTROL under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. Fuel injector volume should be 36-46 cc (2.1-2.8 cu. in.) within 15 seconds and difference in volume between each fuel injector should be less than 10 cc (.6 cu. in.). Fuel injectors should not leak more than one drop every 12 minutes. If fuel injectors are okay, replace heated oxygen sensor No. 1. If fuel injectors are defective, replace fuel injectors as necessary.
7. Using Toyota hand-held tester or scan tool, clear DTCs from ECM. Perform test drive confirmation and then go to next step. See «TEST DRIVE CONFIRMATION»(ref-97394-S28307566252001052100000).
8. Recheck for DTCs. If DTC P0133 does not exist, replace ECM. ECM is located behind glove box. see scheme 3 If DTC P0133 exists, problem is intermittent. Check for defective connections or intermittent problem in wiring and electrical connectors between heated oxygen sensor No. 1 and ECM. ECM is located behind glove box. see scheme 3

1. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Turn ignition on. Using voltmeter, check voltage between body ground and terminal No. 1 (Pink/Blue wire) at ECM electrical connector E10. (Scheme 299) This is the HT1A terminal on ECM. Voltage should be 9-14 volts. If voltage is not within specification, go to next step. If voltage is within specification, replace ECM.
2. Disconnect electrical connector for heated oxygen sensor No. 1. Heated oxygen sensor No. 1 is located on exhaust pipe in front of catalytic converter. Using ohmmeter, check resistance between +B and HT terminals on electrical connector for heated oxygen sensor No. 1. (Scheme 302) Resistance should be 11-16 ohms at 68°F (20°C). If resistance is within specification, go to next step. If resistance is not within specification, replace heated oxygen sensor No. 1.
3. Check wiring harness and electrical connectors between ECM and heated oxygen sensor No. 1, and between heated oxygen sensor No. 1 and EFI main relay. See WIRING DIAGRAMS article. EFI main relay may also be referred to as EFI relay. EFI main relay is located in fuse/relay box at driver's side front corner of engine compartment. Repair wiring harness or electrical connectors as necessary.

Scheme 302

1. Using Toyota hand-held tester or scan tool, check for any other DTCs. If only DTC P0136 exists, go to next step. If other DTCs exist, diagnose and repair those DTCs first and retest.
2. Check for open and short in wiring harness and electrical connectors between heated oxygen sensor No. 2 and ECM. See WIRING DIAGRAMS article. Heated oxygen sensor No. 2 is located on exhaust pipe behind catalytic converter. ECM is located behind glove box. see scheme 3 If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector is defective, repair as necessary.
3. With Toyota hand-held tester or scan tool still connected to DLC No. 3, start engine and warm engine to normal operating temperature. Using hand-held tester or scan tool, monitor heated oxygen sensor No. 2 output voltage while suddenly accelerating engine to 2000 RPM for 3 consecutive times.
4. Heated oxygen sensor No. 2 output voltage should alternate from.40 volt or less to.50 volt or more. If output voltage is not within specification, replace heated oxygen sensor No. 2. If output voltage is within specification, problem is intermittent. Check for defective connections or intermittent problem in wiring and electrical connectors between heated oxygen sensor No. 2 and ECM. See WIRING DIAGRAMS article. ECM is located behind glove box.

1. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Turn ignition on. Using voltmeter, check voltage between body ground and terminal No. 7 (Green/Yellow wire) at ECM electrical connector E10. (Scheme 299) This is the HT1B terminal on ECM. Voltage should be 9-14 volts. If voltage is not within specification, go to next step. If voltage is within specification, replace ECM.
2. Disconnect electrical connector for heated oxygen sensor No. 2. Heated oxygen sensor No. 2 is located on exhaust pipe behind catalytic converter and electrical connector is located below passenger's side carpet, near center console. (Scheme 303)
3. Using ohmmeter, check resistance between +B and HT terminals on electrical connector for heated oxygen sensor No. 2. (Scheme 303) Resistance should be 11-16 ohms at 68°F (20°C). If resistance is within specification, go to next step. If resistance is not within specification, replace heated oxygen sensor No. 2.
4. Check wiring harness and electrical connectors between ECM and heated oxygen sensor No. 2, and between heated oxygen sensor No. 2 and EFI main relay. See WIRING DIAGRAMS article. EFI main relay may also be referred to as EFI relay. EFI main relay is located in fuse/relay box at driver's side front corner of engine compartment. Repair wiring harness or electrical connectors as necessary.

Scheme 303

1. Test drive confirmation may be performed to operate vehicle under conditions which may cause DTC to be set. If using Toyota hand-held tester, go to next step. If Toyota hand-held tester is not available, go to step 4.
2. Connect hand-held tester to Data Link Connector (DLC) No. 3. see scheme 2 Switch hand-held tester from NORMAL mode to CHECK mode.
3. Start engine and allow engine to idle for at least 30 seconds. Drive vehicle at a constant speed for at least 36 seconds. Check operation of Malfunction Indicator Light (MIL). If MIL illuminates, malfunction exists and DTC is set. If MIL does not illuminate, malfunction does not exist.
4. Start engine and allow engine to idle for at least 30 seconds. Drive vehicle at a constant speed for at least 36 seconds. Turn ignition off.
5. Start engine and allow engine to idle for at least 30 seconds. Drive vehicle at a constant speed for at least 36 seconds. Check operation of Malfunction Indicator Light (MIL). If MIL illuminates, malfunction exists and DTC is set. If MIL does not illuminate, malfunction does not exist.

1. Ensure engine oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem does not exist, go to next step. If problem exists, repair as necessary.
2. Check operation of fuel injectors. See FUEL CONTROL under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. Fuel injector volume should be 36-46 cc (2.1-2.8 cu. in.) within 15 seconds and difference in volume between each fuel injector should be less than 10 cc (.6 cu. in.). Fuel injectors should not leak more than one drop every 12 minutes. If fuel injectors are okay, go to next step. If fuel injectors are defective, replace fuel injectors as necessary.
3. Check Mass Airflow (MAF) meter and Engine Coolant Temperature (ECT) sensor. MAF meter may also be referred to as airflow meter. See AIRFLOW METER and ENGINE COOLANT TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If MAF meter and ECT sensor are okay, go to next step. If MAF meter or ECT sensor is defective, replace components as necessary.
4. Check ignition system by performing spark test. See SPARK TEST under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4-CYLINDER article. If ignition system operates properly and spark exists, go to next step. If ignition does not operate properly and spark does not exist, repair ignition system as necessary.
5. Check fuel pressure. See FUEL PRESSURE under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4-CYLINDER article. Fuel pressure should be 44-50 psi (3.1-3.5 kg/cm 2 ) with engine idling and should remain at least 21 psi (1.5 kg/cm 2 ) for a minimum of 5 minutes after engine is shut off. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, repair fuel system as necessary.
6. Check exhaust system for leaks. If no exhaust leak exists, go to next step. If exhaust leak exists, repair exhaust system as necessary.
7. Connect Toyota hand-held tester or scan tool to Data Link Connector (DLC) No. 3. see scheme 2 Start engine and increase engine speed to 2500 RPM for approximately 90 seconds and then allow engine to idle. Using hand-held tester or scan tool, monitor heated oxygen sensor No. 1 output voltage with engine idling. Output voltage should alternate repeatedly from less than.40 volt to more than.55 volt. If output voltage is not as specified, go to next step. If output voltage is as specified, go to step 9.
8. Check for open and short in wiring harness and electrical connectors between heated oxygen sensor No. 1 and ECM. See WIRING DIAGRAMS article. Heated oxygen sensor No. 1 is located on exhaust pipe in front of catalytic converter. ECM is located behind glove box. see scheme 3 If wiring harness and electrical connectors are okay, replace heated oxygen sensor No. 1. If wiring harness or electrical connector is defective, repair as necessary.
9. Using Toyota hand-held tester or scan tool, clear DTCs from ECM. Perform test drive confirmation and then go to next step. See «TEST DRIVE CONFIRMATION»(ref-97394-S41542015172001042700000).
10. Recheck for DTCs. If DTC P0171 or P0172 does not exist, go to next step. If DTC P0171 and/or P0172 exists, replace ECM. ECM is located behind glove box. see scheme 3
11. Verify if vehicle ran out of fuel. If vehicle ran out of fuel, DTC P0171 and/or P0172 was caused by the vehicle running out of fuel. If vehicle did not run out of fuel, problem is intermittent. Check for defective connections or intermittent problem in wiring. ECM is located behind glove box. see scheme 3

1. Test drive confirmation may be performed to operate vehicle under conditions which may cause DTC to be set. Connect Toyota hand-held tester or scan tool to Data Link Connector (DLC) No. 3. see scheme 2 Check for any DTCs and read FREEZE FRAME data. Record DTCs and freeze frame data. If using hand-held tester, switch hand-held tester to CHECK mode.
2. Drive vehicle several times with engine speed, load and its surrounding range shown with ENGINE SPD, CALC LOAD in freeze frame data or MISFIRE RPM and MISFIRE LOAD in the data list on hand-held tester or scan tool.
3. Drive vehicle at specified engine speeds for specified amount of time. See «DRIVING PATTERN»(ref-97394-S24301851252001050400000) table. If using scan tool, turn ignition off after symptom is simulated the first time, then repeat test drive again. If using hand-held tester or scan tool, if a misfire is detected, a DTC will set and misfire will be indicated in freeze frame data. Turn ignition off and wait a minimum of 5 seconds. DRIVING PATTERN RPM Specified Time 1000 3 Minutes Or More 2000 1 1/2 Minutes Or More 3000 1 Minute Or More

Scheme 304

1. Check vacuum hoses for leaks, restrictions and proper routing. See VACUUM DIAGRAMS article for proper vacuum hose routing. Also, check engine wiring harness and electrical connectors for damage or poor connections. If no problems exist, go to next step. If problem exists, repair as necessary and perform «TEST DRIVE CONFIRMATION»(ref-97394-S36725816142001050400000).
2. Remove spark plug for misfiring cylinder. Ensure no carbon deposits exist, spark plug is not fouled and spark plug gap is.039-.047" (1.00-1.20 mm). Check ignition system by performing spark test. See SPARK TEST under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4-CYLINDER article. If ignition system operates properly and spark exists, go to next step. If ignition does not operate properly and spark does not exist, repair ignition system as necessary.
3. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Turn ignition on. Using voltmeter, check voltage between body ground and fuel injector driver terminal for misfiring cylinder at appropriate ECM electrical connector. See «IDENTIFYING ECM FUEL INJECTOR DRIVER TERMINALS»(ref-97394-S08650199162001050400000) table. For ECM electrical connector terminal identification (Scheme 299) If voltage is not 9-14 volts at fuel injector driver terminal, go to next step. If voltage is 9-14 volts at fuel injector driver terminal, go to step 6. IDENTIFYING ECM FUEL INJECTOR DRIVER TERMINALS Fuel Injector No. (1) ECM Electrical Connector & Terminal Wire Color 1 E8 Terminal No. 5 Yellow 2 E8 Terminal No. 6 Black/Red 3 E7 Terminal No. 1 Blue/White 4 E7 Terminal No. 2 Red/White (1) For ECM electrical connector terminal identification (Scheme 299)
4. Disconnect electrical connector at fuel injector on misfiring cylinder. Using ohmmeter, check resistance between electrical terminals on fuel injector. Resistance should be 13.40-14.20 ohms at 68°F (20°C). If resistance is within specification, go to next step. If resistance is not within specification, replace fuel injector.
5. Check for open and short in wiring harness and electrical connectors between fuel injector on misfiring cylinder and ECM. See WIRING DIAGRAMS article. If wiring harness or electrical connector is defective, repair as necessary. If wiring harness and electrical connectors are okay, it may be necessary to check for open and short in wiring harness and electrical connectors in fuel injector power supply circuit. See WIRING DIAGRAMS article.
6. Check fuel pressure. See FUEL PRESSURE under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4-CYLINDER article. Fuel pressure should be 44-50 psi (3.1-3.5 kg/cm 2 ) with engine idling and should remain at least 21 psi (1.5 kg/cm 2 ) for a minimum of 5 minutes after engine is shut off. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, repair fuel system as necessary.
7. Check operation of fuel injector on misfiring cylinder. See FUEL CONTROL under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. Fuel injector volume should be 36-46 cc (2.1-2.8 cu. in.) within 15 seconds and difference in volume between each fuel injector should be less than 10 cc (.6 cu. in.). Fuel injectors should not leak more than one drop every 12 minutes. If fuel injectors are okay, go to next step. If fuel injectors are defective, replace fuel injectors as necessary.
8. Check Mass Airflow (MAF) meter and Engine Coolant Temperature (ECT) sensor. MAF meter may also be referred to as airflow meter. See AIRFLOW METER and ENGINE COOLANT TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If MAF meter and ECT sensor are okay, go to next step. If MAF meter or ECT sensor is defective, replace components as necessary.
9. Check engine compression on misfiring cylinder. See MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 4-CYLINDER article. Check valve clearance on misfiring cylinder. See VALVE CLEARANCE under ENGINE MECHANICAL in ON-VEHICLE ADJUSTMENTS - 4-CYLINDER article. Check valve timing. See appropriate article in ENGINES. Repair engine as necessary.

Circuit Description

Engine Control Module (ECM) uses input signals provided by crankshaft and camshaft position sensors to monitor the changes in crankshaft rotation. If engine speed rate changes enough to equal a preset number, a misfire is detected and Malfunction Indicator Light (MIL) is illuminated. If misfire rate is great enough and driving conditions will cause catalytic converter damage or overheating, the MIL will blink when misfire is occurring. DTC is set when misfiring of any cylinder is detected during any particular 200 revolutions. Possible causes are

1. Open or short in engine wiring harness.
2. Defective connections at ECM or component.
3. Disconnected, restricted or damaged vacuum hose(s).
4. Ignition system malfunction.
5. Defective fuel injector(s).
6. Improper fuel pressure.
7. Defective Mass Airflow (MAF) meter.
8. Defective Engine Coolant Temperature (ECT) sensor.
9. Improper engine compression.
10. Improper valve clearance.
11. Improper valve timing.

Diagnostic Aids

If misfire cannot be reproduced, the reason may be because vehicle was driven with a lack of fuel, improper fuel, fouled spark plug or etc. Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected. If COOLANT TEMP displayed in freeze frame data is less than 176°F (80°C), there is a possibility that misfire only exists during warm-up.

For diagnosis and repair procedure, see DTC P0300: RANDOM MISFIRE DETECTED .

1. Disconnect electrical connector at camshaft position sensor. Camshaft position sensor is located on end of cylinder head at flywheel end of engine and contains a Black 2-pin electrical connector with Green and Red wires.
2. Using ohmmeter, check resistance between electrical terminals on camshaft position sensor. Resistance should be 1630-2740 ohms with sensor temperature of 14-122°F (-10-50°C) and 2065-3225 ohms with sensor temperature of 122-212°F (50-100°C). If resistance is within specification, go to next step. If resistance is not within specification, replace camshaft position sensor. Manufacturer states that converter and inverter assembly must be removed for servicing of camshaft position sensor. The converter and inverter assembly are involved with the high-voltage system used on this vehicle and service procedure should only be performed by authorized dealer.
3. Check for open and short in wiring harness and electrical connectors between camshaft position sensor and ECM. See WIRING DIAGRAMS article. ECM is located behind glove box. see scheme 3 If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector is defective, repair as necessary.
4. Camshaft position sensor should be removed so the sensor and tooth on signal plate on outer circumference of intake camshaft may be inspected. Manufacturer states that converter and inverter assembly must be removed for servicing of camshaft position sensor. The converter and inverter assembly are involved with the high-voltage system used on this vehicle and service procedure should only be performed by authorized dealer. Inspect camshaft position sensor and tooth on signal plate for damage. If camshaft position sensor or signal plate is damaged, replace components as necessary. If camshaft position sensor and signal plate are okay, replace ECM.

1. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Turn ignition on. Using voltmeter, check voltage between terminals No. 2 (Yellow/Red wire) and No. 18 (Brown wire) at ECM electrical connector E8. (Scheme 299) This is the VC and E2 terminals on ECM. Voltage should be 4.5-5.5 volts. If voltage is within specification, go to next step. If voltage is not within specification, replace ECM.
2. Turn ignition off. Connect voltmeter between terminals No. 18 (Brown wire) at ECM electrical connector E8 and No. 22 (Blue/Red wire) at ECM electrical connector E9. (Scheme 299) This is the E2 and PTNK terminals on ECM. Remove fuel tank cap. Turn ignition on and note voltage. Voltage should be 3.0-3.6 volts. If voltage is not within specification, go to next step. If voltage is within specification, replace ECM.
3. Check for open and short in wiring harness and electrical connectors between vapor pressure sensor and ECM. See WIRING DIAGRAMS article. Vapor pressure sensor is located on corner of fuel tank. see scheme 18 If wiring harness and electrical connectors are okay, replace vapor pressure sensor. See VAPOR PRESSURE SENSOR under EMISSION SYSTEMS & SUB-SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article. If wiring harness or electrical connector is defective, repair as necessary.

1. Test drive vehicle and check operation of speedometer. If speedometer operates properly, go to next step. If speedometer does not operate properly, repair speedometer as necessary. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Speedometer may not operate, as input signal from brake ECU may not be input to instrument cluster or defective brake ECU.
2. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Turn ignition on. Using voltmeter, check voltage between body ground and terminal No. 5 (Violet/White wire) at ECM electrical connector E10 while slowly driving vehicle. (Scheme 299) This is the SPD terminal on ECM. Voltage should pulse between zero volts and 4.5-5.5 volts. If voltage is within specification, replace ECM. If voltage is not within specification, repair open or short in wiring between instrument cluster and ECM. See WIRING DIAGRAMS article.

1. Using Toyota hand-held tester or scan tool, check for any other DTCs. If only DTC P0505 exists, go to next step. If other DTCs exists, diagnose and repair those DTCs first and then retest.
2. Ensure engine oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem does not exist, go to next step. If problem exists, repair as necessary.
3. Check throttle body and components for ETCS. See THROTTLE BODY under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article.

1. Check throttle control motor. See THROTTLE BODY under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If throttle control motor is okay, go to next step. If throttle control motor is defective, replace throttle body with throttle control motor as an assembly. See THROTTLE BODY under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article.
2. Remove air intake hose and inspect throttle valve in throttle body for foreign matter between throttle valve and surface of throttle body which may restrict movement of the throttle valve. If foreign material exists, remove foreign material and clean throttle body. If foreign material exist does not exist, replace throttle body. See THROTTLE BODY under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article.

Replace ECM. ECM is located behind glove box. see scheme 3 Using Toyota hand-held tester or scan tool, clear DTCs from ECM. Recheck for DTCs. If DTC P1129 still exists, replace throttle body. See THROTTLE BODY under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article.

1. Check for spark at cylinder No. 1 by performing spark test. See SPARK TEST under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4-CYLINDER article. Cylinder No. 1 is the front cylinder at timing chain end of engine and uses the ignition coil No. 1. If spark exists, go to next step. If spark does not exist, go to step 4.
2. Check for open and short in Yellow/Green and Black/Red wires and electrical connectors between ECM and ignition coil No. 1. See WIRING DIAGRAMS article. ECM is located behind glove box. see scheme 3 If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector is defective, repair as necessary.
3. Disconnect electrical connector at ignition coil No. 1. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Turn ignition on. Using voltmeter, check voltage between body ground and terminal No. 25 (Black/Red wire) at ECM electrical connector E7. (Scheme 299) This is the IGF terminal on ECM. Voltage should 4.5-5.5 volts. If voltage is within specification, replace ignition coil No. 1. If voltage is not within specification, replace ECM.
4. Check for open and short in Yellow/Green wire and electrical connectors between ECM and ignition coil No. 1. See WIRING DIAGRAMS article. ECM is located behind glove box. see scheme 3 If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector is defective, repair as necessary.
5. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Using voltmeter, check voltage between body ground and terminal No. 11 (Yellow/Green wire) at ECM electrical connector E7 while cranking engine. (Scheme 299) This is the IGT1 terminal on ECM. Voltage should be more than.1 volt and less than 4.5 volts. If voltage is not within specification, go to next step. If voltage is within specification, go to step 7.
6. Disconnect electrical connector at ignition coil No. 1. Using voltmeter, check voltage between body ground and terminal No. 11 (Yellow/Green wire) at ECM electrical connector E7 while cranking engine. (Scheme 299) This is the IGT1 terminal on ECM. Voltage should be more than.1 volt and less than 4.5 volts. If voltage is within specification, replace ignition coil No. 1. If voltage is not within specification, replace ECM.
7. Using voltmeter, check voltage between body ground and terminal No. 1 (Black/White wire) at electrical connector for ignition coil No. 1 with ignition switch in ON and START positions. (Scheme 305) Voltage should be 9-14 volts. If voltage is within specification, go to next step. If voltage is not within specification, check power supply circuit between ignition switch, IG2 relay and ignition coil No. 1. See WIRING DIAGRAMS article. IG2 relay provides voltage for power supply circuit to ignition coil No. 1. IG2 relay is located in fuse/relay box at driver's side front corner of engine compartment.
8. Check for open in White/Black wire and electrical connectors between ground and ignition coil No. 1. See WIRING DIAGRAMS article. If wiring harness and electrical connectors are okay, replace ignition coil No. 1. If wiring harness or electrical connector is defective, repair as necessary.

Scheme 305

1. Check for spark at cylinder No. 2 by performing spark test. See SPARK TEST under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4-CYLINDER article. Cylinder No. 2 is second cylinder from timing chain end of engine and uses the ignition coil No. 2. If spark exists, go to next step. If spark does not exist, go to step 4.
2. Check for open and short in White and Black/Red wires and electrical connectors between ECM and ignition coil No. 2. See WIRING DIAGRAMS article. ECM is located behind glove box. see scheme 3 If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector is defective, repair as necessary.
3. Disconnect electrical connector at ignition coil No. 2. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Turn ignition on. Using voltmeter, check voltage between body ground and terminal No. 25 (Black/Red wire) at ECM electrical connector E7. (Scheme 299) This is the IGF terminal on ECM. Voltage should 4.5-5.5 volts. If voltage is within specification, replace ignition coil No. 2. If voltage is not within specification, replace ECM.
4. Check for open and short in White wire and electrical connectors between ECM and ignition coil No. 2. See WIRING DIAGRAMS article. ECM is located behind glove box. see scheme 3 If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector is defective, repair as necessary.
5. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Using voltmeter, check voltage between body ground and terminal No. 12 (White wire) at ECM electrical connector E7 while cranking engine. (Scheme 299) This is the IGT2 terminal on ECM. Voltage should be more than.1 volt and less than 4.5 volts. If voltage is not within specification, go to next step. If voltage is within specification, go to step 7.
6. Disconnect electrical connector at ignition coil No. 2. Using voltmeter, check voltage between body ground and terminal No. 12 (White wire) at ECM electrical connector E7 while cranking engine. (Scheme 299) This is the IGT2 terminal on ECM. Voltage should be more than.1 volt and less than 4.5 volts. If voltage is within specification, replace ignition coil No. 2. If voltage is not within specification, replace ECM.
7. Using voltmeter, check voltage between body ground and terminal No. 1 (Black/White wire) at electrical connector for ignition coil No. 2 with ignition switch in ON and START positions. (Scheme 305) Voltage should be 9-14 volts. If voltage is within specification, go to next step. If voltage is not within specification, check power supply circuit between ignition switch, IG2 relay and ignition coil No. 2. See WIRING DIAGRAMS article. IG2 relay provides voltage for power supply circuit to ignition coil No. 2. IG2 relay is located in fuse/relay box at driver's side front corner of engine compartment.
8. Check for open in White/Black wire and electrical connectors between ground and ignition coil No. 2. See WIRING DIAGRAMS article. If wiring harness and electrical connectors are okay, replace ignition coil No. 2. If wiring harness or electrical connector is defective, repair as necessary.

1. Check for spark at cylinder No. 3 by performing spark test. See SPARK TEST under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4-CYLINDER article. Cylinder No. 3 is third cylinder from timing chain end of engine and uses the ignition coil No. 3. If spark exists, go to next step. If spark does not exist, go to step 4.
2. Check for open and short in Green and Black/Red wires and electrical connectors between ECM and ignition coil No. 3. See WIRING DIAGRAMS article. ECM is located behind glove box. see scheme 3 If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector is defective, repair as necessary.
3. Disconnect electrical connector at ignition coil No. 3. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Turn ignition on. Using voltmeter, check voltage between body ground and terminal No. 25 (Black/Red wire) at ECM electrical connector E7. (Scheme 299) This is the IGF terminal on ECM. Voltage should 4.5-5.5 volts. If voltage is within specification, replace ignition coil No. 3. If voltage is not within specification, replace ECM.
4. Check for open and short in Green wire and electrical connectors between ECM and ignition coil No. 3. See WIRING DIAGRAMS article. ECM is located behind glove box. see scheme 3 If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector is defective, repair as necessary.
5. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Using voltmeter, check voltage between body ground and terminal No. 13 (Green wire) at ECM electrical connector E7 while cranking engine. (Scheme 299) This is the IGT3 terminal on ECM. Voltage should be more than.1 volt and less than 4.5 volts. If voltage is not within specification, go to next step. If voltage is within specification, go to step 7.
6. Disconnect electrical connector at ignition coil No. 3. Using voltmeter, check voltage between body ground and terminal No. 13 (Green wire) at ECM electrical connector E7 while cranking engine. (Scheme 299) This is the IGT3 terminal on ECM. Voltage should be more than.1 volt and less than 4.5 volts. If voltage is within specification, replace ignition coil No. 3. If voltage is not within specification, replace ECM.
7. Using voltmeter, check voltage between body ground and terminal No. 1 (Black/White wire) at electrical connector for ignition coil No. 3 with ignition switch in ON and START positions. (Scheme 305) Voltage should be 9-14 volts. If voltage is within specification, go to next step. If voltage is not within specification, check power supply circuit between ignition switch, IG2 relay and ignition coil No. 3. See WIRING DIAGRAMS article. IG2 relay provides voltage for power supply circuit to ignition coil No. 3. IG2 relay is located in fuse/relay box at driver's side front corner of engine compartment.
8. Check for open in White/Black wire and electrical connectors between ground and ignition coil No. 3. See WIRING DIAGRAMS article. If wiring harness and electrical connectors are okay, replace ignition coil No. 3. If wiring harness or electrical connector is defective, repair as necessary.

1. Check for spark at cylinder No. 4 by performing spark test. See SPARK TEST under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4-CYLINDER article. Cylinder No. 4 is fourth cylinder from timing chain end of engine and uses the ignition coil No. 4. If spark exists, go to next step. If spark does not exist, go to step 4.
2. Check for open and short in Yellow and Black/Red wires and electrical connectors between ECM and ignition coil No. 4. See WIRING DIAGRAMS article. ECM is located behind glove box. see scheme 3 If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector is defective, repair as necessary.
3. Disconnect electrical connector at ignition coil No. 4. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Turn ignition on. Using voltmeter, check voltage between body ground and terminal No. 25 (Black/Red wire) at ECM electrical connector E7. (Scheme 299) This is the IGF terminal on ECM. Voltage should 4.5-5.5 volts. If voltage is within specification, replace ignition coil No. 4. If voltage is not within specification, replace ECM.
4. Check for open and short in Yellow wire and electrical connectors between ECM and ignition coil No. 4. See WIRING DIAGRAMS article. ECM is located behind glove box. see scheme 3 If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector is defective, repair as necessary.
5. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Using voltmeter, check voltage between body ground and terminal No. 14 (Yellow wire) at ECM electrical connector E7 while cranking engine. (Scheme 299) This is the IGT4 terminal on ECM. Voltage should be more than.1 volt and less than 4.5 volts. If voltage is not within specification, go to next step. If voltage is within specification, go to step 7.
6. Disconnect electrical connector at ignition coil No. 4. Using voltmeter, check voltage between body ground and terminal No. 14 (Yellow wire) at ECM electrical connector E7 while cranking engine. (Scheme 299) This is the IGT4 terminal on ECM. Voltage should be more than.1 volt and less than 4.5 volts. If voltage is within specification, replace ignition coil No. 4. If voltage is not within specification, replace ECM.
7. Using voltmeter, check voltage between body ground and terminal No. 1 (Black/White wire) at electrical connector for ignition coil No. 4 with ignition switch in ON and START positions. (Scheme 305) Voltage should be 9-14 volts. If voltage is within specification, go to next step. If voltage is not within specification, check power supply circuit between ignition switch, IG2 relay and ignition coil No. 4. See WIRING DIAGRAMS article. IG2 relay provides voltage for power supply circuit to ignition coil No. 4. IG2 relay is located in fuse/relay box at driver's side front corner of engine compartment.
8. Check for open in White/Black wire and electrical connectors between ground and ignition coil No. 4. See WIRING DIAGRAMS article. If wiring harness and electrical connectors are okay, replace ignition coil No. 4. If wiring harness or electrical connector is defective, repair as necessary.

Check valve timing while checking for loose, stretched or jumped teeth on timing chain. See appropriate article in ENGINES. If no problem exist, replace ECM. ECM is located behind glove box. see scheme 3 If problem exists, repair or replace components as necessary.

1. Check valve timing. See appropriate article in ENGINES. If no problem exist, go to next step. If problem exists, repair or replace components as necessary.
2. If using Toyota hand-held tester, go to next step. If Toyota hand-held tester is not available, go to step 11.
3. Connect hand-held tester to Data Link Connector (DLC) No. 3. see scheme 2 Start engine and warm engine to normal operating temperature. Allow engine to idle.
4. Select ACTIVE TEST mode and then VVT on hand-held tester to operate the VVT OCV. Note engine idle when VVT OCV is operated by hand-held tester. Engine idle should be normal with VVT OCV off and should become rough or engine may stall when VVT OCV is on. If engine idle does not function as specified, shut engine off. Go to next step. If engine idle is as specified, VVT OCV is functioning properly at this time. DTC may have been set because of a foreign object that was temporarily caught in engine oil system but after a short time system returned to normal.
5. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Connect oscilloscope between terminals No. 23 (Yellow/Red wire) and No. 24 (White/Green wire) at ECM electrical connector E7. (Scheme 299)This is the OCV+ and OCV- terminals on ECM.
6. Start engine and allow engine to idle. Ensure VVT OCV signal waveform pattern is as shown in illustration. (Scheme 306) As engine speed is increased, waveform pattern frequency "A" should lengthen. If signal waveform pattern is as shown, shut engine off. Go to next step. If signal waveform pattern is not as shown, Shut engine off. Replace ECM.
7. Check VVT controller assembly for proper operation. If VVT controller assembly operates properly, go to next step. If VVT controller assembly does not operate properly, replace VVT controller assembly and go to next step.
8. Check VVT OCV resistance and operation. See VARIABLE VALVE TIMING CAMSHAFT TIMING OIL CONTROL VALVE under VARIABLE VALVE TIMING SYSTEM in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If VVT OCV is okay, go to next step. If VVT OCV is defective, replace VVT OCV and go to next step.
9. Check for restrictions in VVT OCV, oil filter for VVT OCV and oil passage for VVT OCV. Oil filter for VVT OCV is located behind plug, just below VVT OCV. (Scheme 308) If no problem exist, go to next step. If problem exists, repair or replace components as necessary.
10. Using hand-held tester, clear DTCs from ECM. Start engine and allow engine to idle. Shut engine off. Turn ignition on. Using hand-held tester, check for DTCs. If DTC P1349 exists, replace ECM. If DTC P1349 does not exist, no problem is indicated at this time. DTC may have been set because of a foreign object that was temporarily caught in engine oil system but after a short time system returned to normal.
11. Start engine and warm engine to normal operating temperature. Allow engine to idle. Note engine idle while disconnecting electrical connector at VVT OCV. VVT OCV is located at intake manifold side of cylinder head, near timing chain end of engine. (Scheme 307) Engine idle should not change. Using jumper wires, apply battery voltage and ground to electrical terminals on VVT OCV. Engine should idle rough or stall. If VVT OCV operates as specified, shut engine off. Go to next step. If VVT OCV does not operate as specified, shut engine off. Go to step 14.
12. Reinstall electrical connector on VVT OCV. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Connect oscilloscope between terminals No. 23 (Yellow/Red wire) and No. 24 (White/Green wire) at ECM electrical connector E7. (Scheme 299) This is the OCV+ and OCV- terminals on ECM.
13. Start engine and allow engine to idle. Ensure VVT OCV signal waveform pattern is as shown in illustration. (Scheme 306) As engine speed is increased, waveform pattern frequency "A" should lengthen. If signal waveform pattern is not as shown, shut engine off. Replace ECM. If signal waveform pattern is as shown, shut engine off. VVT OCV is functioning properly at this time. DTC may have been set because of a foreign object that was temporarily caught in engine oil system but after a short time system returned to normal.
14. Check VVT controller assembly for proper operation. If VVT controller assembly operates properly, go to next step. If VVT controller assembly does not operate properly, replace VVT controller assembly and go to next step.
15. Check VVT OCV resistance and operation. See VARIABLE VALVE TIMING CAMSHAFT TIMING OIL CONTROL VALVE under VARIABLE VALVE TIMING SYSTEM in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If VVT OCV is okay, go to next step. If VVT OCV is defective, replace VVT OCV. and go to next step.
16. Check for blockage in VVT OCV, oil filter for VVT OCV and oil passage for VVT OCV. Oil filter for VVT OCV is located behind plug, just below VVT OCV. (Scheme 308) If no problem exist, go to next step. If problem exists, repair or replace components as necessary.
17. Using scan tool, clear DTCs from ECM. Start engine and allow engine to idle. Shut engine off. Turn ignition on. Using scan tool, check for DTCs. If DTC P1349 exists, replace ECM. If DTC P1349 does not exist, no problem is indicated at this time. DTC may have been set because of a foreign object that was temporarily caught in engine oil system but after a short time system returned to normal.

Scheme 306

Scheme 307

Scheme 308

1. Using Toyota hand-held tester or scan tool, check for any other DTCs. If only DTC P1431 exists, go to next step. If other DTCs exists, diagnose and repair those DTCs first and then retest.
2. Check operation of vacuum sensor. See VACUUM SENSOR FOR HYDROCARBON ADSORBER CATALYST SYSTEM under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If vacuum sensor operates properly, check for restricted vacuum line to vacuum sensor and repair as necessary. If vacuum sensor does not operate properly, replace vacuum sensor.

1. Using Toyota hand-held tester or scan tool, check for any other DTCs. If only DTC P1455 exists, go to next step. If other DTCs exists, diagnose and repair those DTCs first and then retest.
2. Remove fuel tank. See FUEL PUMP under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article for fuel tank servicing procedures. Turn fuel tank upside down and check that fuel does not come out of fuel tank from any other areas than the main fuel hose.
3. If fuel does not come out of fuel tank in any other areas than the main fuel, replace ECM. ECM is located behind glove box. see scheme 3 If fuel comes out of fuel tank in any other areas than the main fuel hose, replace fuel tank. It may be necessary to check and replace charcoal canister and hoses to intake manifold. Charcoal canister is located near fuel tank. see scheme 18

1. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Connect voltmeter between body ground and terminal No. 10 (Orange wire) at ECM electrical connector E9. (Scheme 299) This is the SPHV terminal on ECM. Drive vehicle at 12 MPH and note voltage. Voltage should pulsate between zero volts and 4.5-5.5 volts. If voltage does not pulsate as specified, go to next step. If voltage pulsates as specified, replace ECM.
2. Check for open and short in Orange wire and electrical connectors between terminal No. 10 at ECM electrical connector E9 and terminal No. 6 at HV ECU electrical connector H14. For HV ECU electrical terminal identification (Scheme 300) HV ECU is located below carpet on floor panel, just below passenger's side of instrument panel. see scheme 4
3. If wiring harness or electrical connector is defective, repair as necessary. If wiring harness and electrical connectors are okay, replace HV ECU. If HV ECU is replaced, the HV ECU must be reprogrammed for the engine immobilizer system. Engine immobilizer system may also be referred to as Hybrid Vehicle (HV) immobilizer system. For programming procedures, see «HYBRID VEHICLE ELECTRONIC CONTROL UNIT PROGRAMMING»(ref-97394-S29189789812001042700000) under PROGRAMMING.

1. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Ensure ignition is off. Using voltmeter, check voltage between body ground and terminal No. 3 (Red/White wire) at ECM electrical connector E8. (Scheme 299) This is the BATT terminal on ECM. Voltage should be 9-14 volts. If voltage is not within specification, go to next step. If voltage is within specification, replace ECM.
2. Remove EFI fuse (15-amp) from fuse/relay box at driver's side front corner of engine compartment. see scheme 25 Check EFI fuse. If EFI fuse is okay, reinstall EFI fuse. Check wiring harness and electrical connectors between EFI fuse and ECM. See WIRING DIAGRAMS article. It may be necessary to check wiring between battery and EFI fuse. For additional wiring for EFI fuse to the battery, see POWER DISTRIBUTION article in WIRING DIAGRAMS. If EFI fuse is defective, replace fuse and check for short in wiring harness and components connected to EFI fuse. See WIRING DIAGRAMS article. Repair wiring harness or electrical connectors as necessary.

If DTC P1633 exists, replace ECM. ECM is located behind glove box. see scheme 3

1. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Start engine and allow engine to idle. Using voltmeter, check voltage between body ground and terminal No. 16 (Red/Yellow wire) at ECM electrical connector E9. (Scheme 299) This is the ESTP terminal on ECM. Voltage should be 9-14 volts. Shut engine off. If voltage is not within specification, go to next step. If voltage is within specification, replace ECM.
2. Check for open and short in Red/Yellow wire and electrical connectors between terminal No. 16 at ECM electrical connector E9 and terminal No. 8 at HV ECU electrical connector H14. This is the ESTP terminal on ECM. For HV ECU electrical terminal identification (Scheme 300) HV ECU is located below carpet on floor panel, just below passenger's side of instrument panel. see scheme 4
3. If wiring harness or electrical connector is defective, repair as necessary. If wiring harness and electrical connectors are okay, replace HV ECU. If HV ECU is replaced, the HV ECU must be reprogrammed for the engine immobilizer system. Engine immobilizer system may also be referred to as Hybrid Vehicle (HV) immobilizer system. For programming procedures, see «HYBRID VEHICLE ELECTRONIC CONTROL UNIT PROGRAMMING»(ref-97394-S29189789812001042700000) under PROGRAMMING.

1. If using Toyota hand-held tester, go to next step. If Toyota hand-held tester is not available, go to step 4.
2. Connect hand-held tester to Data Link Connector (DLC) No. 3. see scheme 2 Start engine and warm engine to normal operating temperature. Allow engine to idle.
3. Select ACTIVE TEST mode and then VVT on hand-held tester to operate the VVT OCV. Note engine idle when VVT OCV is operated by hand-held tester. Engine idle should be normal with VVT OCV off and should become rough or engine may stall when VVT OCV is on. If engine idle does not function as specified, shut engine off. Go to next step. If engine idle is as specified, VVT OCV is functioning properly at this time. DTC may have been set due to intermittent problem in wiring harness or electrical connectors between ECM and VVT OCV.
4. Disconnect electrical connector at VVT OCV. VVT OCV is located at intake manifold side of cylinder head, near timing chain end of engine. (Scheme 307) Start engine and allow engine to idle. With engine idling, using jumper wires, apply battery voltage and ground to electrical terminals on VVT OCV. Engine should idle rough or stall. If VVT OCV operates as specified, shut engine off. Go to next step. If VVT OCV does not operate as specified, shut engine off. Replace VVT OCV. See VARIABLE VALVE TIMING CAMSHAFT TIMING OIL CONTROL VALVE under VARIABLE VALVE TIMING SYSTEM in REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article.
5. Reinstall electrical connector on VVT OCV. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 3 Connect oscilloscope between terminals No. 23 (Yellow/Red wire) and No. 24 (White/Green wire) at ECM electrical connector E7. (Scheme 299) This is the OCV+ and OCV- terminals on ECM.
6. Start engine and allow engine to idle. Ensure VVT OCV signal waveform pattern is as shown in illustration. (Scheme 306) As engine speed is increased, waveform pattern frequency "A" should lengthen. If signal waveform pattern is as shown, shut engine off. Go to next step. If signal waveform pattern is not as shown, shut engine off. Replace ECM.
7. Check for open and short in wiring harness and electrical connectors between VVT OCV and ECM. See WIRING DIAGRAMS article. If wiring harness and electrical connectors are okay, problem is intermittent. Check for defective connections or intermittent problem in wiring between VVT OCV and ECM. If wiring harness or electrical connector is defective, repair as necessary.

1. Using Toyota hand-held tester or scan tool, check for any other DTCs. If only DTC P3190 or DTC P3191 exists, go to next step. If other DTCs exists, diagnose and repair those DTCs first and then retest.
2. Check vehicle for being out of fuel. If vehicle is not out of fuel, go to next step. If vehicle is out of fuel, add fuel.
3. Ensure engine oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem does not exist, go to next step. If problem exists, repair as necessary.
4. Check for unusual noise or vibration when starting or accelerating the engine. If no unusual noise or vibration exists, go to next step. If unusual noise or vibration exists, repair or replace engine as necessary.
5. Check fuel pressure. See FUEL PRESSURE under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4-CYLINDER article. Fuel pressure should be 44-50 psi (3.1-3.5 kg/cm 2 ) with engine idling and should remain at least 21 psi (1.5 kg/cm 2 ) for a minimum of 5 minutes after engine is shut off. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, repair fuel system as necessary.
6. Check Mass Airflow (MAF) meter and Engine Coolant Temperature (ECT) sensor. MAF meter may also be referred to as airflow meter. See AIRFLOW METER and ENGINE COOLANT TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If MAF meter and ECT sensor are okay, go to next step. If MAF meter or ECT sensor is defective, replace components as necessary.
7. Remove passenger's side lower engine cover for access to crankshaft position sensor. Crankshaft position sensor is located on front of engine, near crankshaft pulley. see scheme 15 Disconnect electrical connector at crankshaft position sensor.
8. Using ohmmeter, check resistance between electrical terminals on crankshaft position sensor. Resistance should be 985-1600 ohms with sensor temperature of 14-122°F (-10-50°C) and 1265-1890 ohms with sensor temperature of 122-212°F (50-100°C). If resistance is within specification, go to next step. If resistance is not within specification, replace crankshaft position sensor. See CRANKSHAFT POSITION SENSOR under IGNITION SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article.
9. Disconnect electrical connector at camshaft position sensor. Camshaft position sensor is located on end of cylinder head at flywheel end of engine and contains a Black 2-pin electrical connector with Green and Red wires.
10. Using ohmmeter, check resistance between electrical terminals on camshaft position sensor. Resistance should be 1630-2740 ohms with sensor temperature of 14-122°F (-10-50°C) and 2065-3225 ohms with sensor temperature of 122-212°F (50-100°C). If resistance is within specification, go to next step. If resistance is not within specification, replace camshaft position sensor. Manufacturer states that converter and inverter assembly must be removed for servicing of camshaft position sensor. The converter and inverter assembly are involved with the high-voltage system used on this vehicle and service procedure should only be performed by authorized dealer.
11. Check throttle control motor. See THROTTLE BODY under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If throttle control motor is okay, go to next step. If throttle control motor is defective, replace throttle body with throttle control motor as an assembly. See THROTTLE BODY under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article.
12. Check Throttle Position (TP) sensor. See THROTTLE BODY under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - 4-CYLINDER article. If TP sensor is okay, replace ECM. ECM is located behind glove box. see scheme 3 If TP sensor is defective, replace TP sensor. See THROTTLE BODY under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - 4-CYLINDER article.