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Engine Controls - Self-Diagnostics - LS430: Diagnosis Lexus LS III

Testing & Diagnostics 13 illustrations ~13672 words

MALFUNCTION INDICATOR LIGHT (MIL) INSPECTION

Note. CHECK engine light located on instrument cluster is known as Malfunction Indicator Light (MIL). Inspect MIL to ensure it is operational and will come on if a Diagnostic Trouble Code (DTC) is set.

  1. Turn ignition on with engine off. MIL should come on and remain on. If MIL does not come on, check bulb circuit on instrument cluster and wiring circuit between MIL and ECM. See WIRING DIAGRAMS article.
  2. Start engine and ensure MIL goes off. If MIL remains on with engine running, a malfunction is detected. Proceed to «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22522-S10006286822001010300000) .

TESTING PROCEDURE

To ensure correct diagnosis and repair, testing should be done in 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 Connect appropriate OBD-II scan tool. Retrieve codes and record any freeze-frame data. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22522-S10006286822001010300000) .
  3. Clear Trouble Codes Clear DTCs using scan tool. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-22522-S27929095292001010300000) .
  4. Perform Visual Inspection Inspect all connectors of suspect circuit or component. Ensure all connections are clean and tight.
  5. Confirm Symptoms & Trouble Codes Perform road test. Determine if original symptoms are still present. Retrieve codes.
  6. Diagnose & Repair Diagnostic Trouble Codes Perform diagnosis and repair procedures as needed. See «DIAGNOSTIC TESTS»(ref-22522-S19059779852001010300000) . If no codes are present, proceed to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.).
  7. Verification Procedure After repairs have been completed, clear all DTCs. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-22522-S27929095292001010300000) . Perform road test. Ensure no codes are present and all symptoms and/or complaints have been repaired.

RETRIEVING DIAGNOSTIC TROUBLE CODES

Diagnostic Trouble Codes (DTCs) may be retrieved using Lexus scan tool or On-Board Diagnostic (OBD-II) scan tool that complies with SAE standard J-1978. Lexus scan tool or OBD-II scan tool may be operated in NORMAL mode when retrieving trouble codes. If no codes are stored in NORMAL mode, Lexus scan tool may be used in CHECK mode to determine if any first trip DTCs are stored. OBD-II scan tools that comply with SAE standard J-1979 may be used in MODE 7 (CONTINUOUS TEST RESULTS function) to determine if any first trip DTCs are stored. NORMAL mode is used to retrieve DTCs from Engine Control Module (ECM). MODE 7 or CHECK mode is used to check for DTCs when operating vehicle to simulate conditions in which DTC was set. CHECK mode contains a higher sensing ability to detect malfunctions and helps locate problems caused by poor electrical connections, which are difficult to determine using NORMAL mode.

Note. If using Lexus scan tool, when scan tool is switched from NORMAL mode to CHECK mode, all DTCs and freeze-frame data will be erased. DO NOT switch modes until all DTCs and freeze-frame data are recorded.

CHECK Mode Code Retrieval (Lexus Scan Tool Only)

  1. Ensure vehicle battery is fully charged (at least 11 volts). Shift transmission/transaxle into Neutral (M/T) or Park (A/T). Turn A/C and all accessories off. Ensure throttle is in idle position.
  2. Turn ignition off. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 DLC No. 3 connector is located under left side of instrument panel. Turn ignition on with engine off. Turn scan tool on.
  3. Switch scan tool from NORMAL mode to CHECK mode. CHECK mode is operational if MIL on instrument cluster flashes. Start engine. Ensure MIL goes off. Try to simulate conditions of driveability complaint described by customer. NOTE: If ignition is turned from ON to ACC or OFF position, all DTCs and freeze-frame data will be erased. DO NOT switch modes or turn ignition off until all DTCs and freeze-frame data are recorded.
  4. Record any DTCs and freeze-frame data displayed for system diagnosis. If driveability problem exists and no codes are present, go to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom.
  5. If any DTCs are present, perform appropriate circuit test. See «DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION»(ref-22522-S11860364142001010300000) table. For more information on freeze-frame data, see «FREEZE-FRAME DATA»(ref-22522-S18805791892001010300000) under INTRODUCTION. For information on 2-trip detection logic codes, see «TWO-TRIP DETECTION LOGIC»(ref-22522-S08646028112001010300000) under INTRODUCTION.
  6. After repairs for DTC have been completed, DTC must be cleared from ECM memory. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-22522-S27929095292001010300000).

CLEARING DIAGNOSTIC TROUBLE CODES

  1. After performing repairs, clear ECM memory of all stored Diagnostic Trouble Codes (DTCs) and freeze-frame data. DTCs and freeze-frame data may be cleared using scan tool and by following scan tool manufacturer's instructions. NOTE: If using Lexus Scan Tool, DTCs and freeze-frame data may be cleared by switching from CHECK mode to NORMAL mode or from NORMAL mode to CHECK mode.
  2. DTCs and freeze-frame data may also be cleared by removing EFI fuse and ECTS fuses (if equipped with electronic throttle control system) from fuse/relay box located in engine compartment. DTCs and freeze-frame data may also be cleared by disconnecting negative battery cable. However, other memory functions (clock, radio, alarm, seats, etc.) will be cancelled and must be reset.

TROUBLE CODE TEST DRIVE CONFIRMATION

  1. On certain Diagnostic Trouble Codes (DTCs), once DTC has been cleared from ECM memory, a DTC test drive confirmation test can be performed to verify repairs 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 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 with proper DTC diagnostic test in DIAGNOSTIC TESTS.

DLC NO. 3 INSPECTION

  1. If scan tool displays UNABLE TO CONNECT TO VEHICLE when scan tool is connected, try scan tool on another vehicle. If scan tool operates on another vehicle, go to next step. If scan tool does not operate on another vehicle, problem is probably with 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. Repair as necessary. If connector and terminals are okay, go to next step.
  3. Check voltage and resistance between ground and specified terminal on DLC No. 3. See «DLC NO. 3 VOLTAGE & RESISTANCE SPECIFICATIONS»(ref-22522-S16880380212001010300000) table. (Scheme 66) If voltage and resistance readings are not as specified, check wiring circuit. See WIRING DIAGRAMS article.
Terminal No. (Application)Specification
4 (Chassis Ground)One Ohm Or Less
5 (Signal)One Ohm Or Less
7 (BUS+ Line)(1)
16 (Battery Voltage)9-14 Volts
(1) Terminal No. 7 of DLC No. 3 provides a pulse generation during the information transmission from the Engine Control Module (ECM).
(1)Terminal No. 7 of DLC No. 3 provides a pulse generation during the information transmission from the Engine Control Module (ECM).

DLC NO. 3 VOLTAGE & RESISTANCE SPECIFICATIONS

Scheme 66

Scheme 66
Scheme 66

DIAGNOSTIC TESTS

CAUTIONPerform all resistance and voltage tests with a Digital Volt-ohmmeter (DVOM) with minimum 10-megohm impedance, unless stated otherwise in test procedures. Ensure ignition switch is in OFF position when performing resistance tests.

Note. For component locations, see appropriate illustration in THEORY & OPERATION article.

Note. For identification of circuits, terminals and wire colors referenced in following testing, see WIRING DIAGRAMS article.

Diagnosis & Repair

  1. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Turn ignition on. Start engine and allow it to idle. Using scan tool, monitor MAF rate. If scan tool reading is 0.0 gm/sec., go to next step. If reading is 271.0 gm/sec. or more, go to step 5.
  2. Disconnect MAF sensor connector. Turn ignition on. Using DVOM, measure voltage between ground and terminal No. 1 (White wire) at MAF sensor harness connector. If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, locate and repair open in White wire between MAF sensor connector and EFI main relay. EFI main relay is located in engine compartment fuse/relay block on passenger's side firewall.
  3. Access ECM at left front of engine compartment. Start engine. Ensure transmission is in Park or Neutral and A/C is off. Backprobing connector, measure voltage between ground and terminal No. 27 (Blue/Yellow wire) at ECM E4 connector. (Scheme 67) If voltage is.5-3.0 volts, replace ECM and retest. If voltage is not.5-3.0 volts, go to next step.
  4. Check for an open or short in Blue/Yellow wire between MAF sensor and ECM E4 connector. Repair wiring harness as necessary. If wiring is okay, replace MAF sensor and retest.
  5. Turn ignition off. Backprobing connector, check for continuity between ground and terminal No. 26 (Green/White wire) at ECM E4 connector. If continuity does not exist, replace ECM and retest. If continuity exists, go to next step.
  6. Check for open in Green/White wire between MAF sensor and ECM E4 connector. Repair as necessary. If wire is okay, replace MAF sensor.

Scheme 67

Scheme 67
Scheme 67

Retrieve trouble codes. See RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. If only DTC P0101 is displayed, replace MAF sensor and retest. If other codes are displayed, diagnose and repair those codes first and retest.

  1. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Turn ignition on. Turn scan tool on. Using scan tool, monitor IAT sensor temperature. If temperature displayed is same as actual intake air temperature, check IAT sensor and ECM connections. Problem is intermittent. If temperature displayed is -40°F (-40°C), go to next step. If temperature displayed is 284°F (140°C) or more, go to step 4.
  2. Turn ignition off. Disconnect MAF sensor connector. Connect a fused jumper wire between terminals No. 4 (Pink/Blue wire) and No. 5 (Brown wire) at MAF sensor harness connector. Turn ignition on. Using scan tool, monitor IAT sensor temperature. If temperature displayed is 284°F (140°C) or more, check MAF sensor connector for corrosion, damage or loose terminals. If connector is okay, replace MAF sensor and retest. If temperature displayed is less than 284°F (140°C), go to next step.
  3. Turn ignition off. Remove fused jumper wire. Backprobing connector, connect a fused jumper wire between terminals No. 32 (Pink/Blue wire) and No. 31 (Brown wire) at ECM E4 connector. (Scheme 67) If temperature displayed on scan tool is 284°F (140°C) or more, check for an open in Pink/Blue wire or Brown wire between MAF sensor harness connector and ECM E4 connector. If temperature displayed on scan tool is not 284°F (140°C) or more, replace ECM and retest.
  4. Turn ignition off. Disconnect MAF sensor connector. Turn ignition on. If temperature displayed on scan tool is -40°F (-40°C), replace MAF sensor and retest. If temperature displayed is not -40°F (-40°C), turn ignition off and go to next step.
  5. Disconnect E4 connector from ECM. Turn ignition on. If temperature displayed is -40°F (-40°C), locate and repair short in Pink/Blue or Brown wire between MAF sensor and ECM E4 connector. If temperature displayed by scan tool is not -40°F (-40°C), replace ECM and retest.
  1. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Turn ignition on. Turn scan tool on. Using scan tool, monitor ECT sensor temperature. If temperature displayed is same as actual coolant temperature, problem is intermittent. If temperature displayed is -40°F (-40°C), go to next step. If temperature displayed is 284°F (140°C), go to step 4.
  2. Turn ignition off. Disconnect ECT sensor connector. Connect a fused jumper wire between ECT sensor harness connector terminals. Turn ignition on. Using scan tool, monitor ECT sensor temperature. If temperature displayed is 284°F (140°C) or more, check ECT sensor connector for corrosion, damage or loose terminals. If sensor connector is okay, replace ECT sensor and retest. If temperature displayed is not 284°F (140°C) or more, go to next step.
  3. Turn ignition off. Remove fused jumper wire. Backprobing connector, connect fused jumper wire between terminals No. 24 (Red/Blue wire) and No. 25 (Brown wire) at ECM E4 connector. (Scheme 67) If temperature displayed on scan tool is 284°F (140°C) or more, check for an open in Red/Blue wire or Brown wire between ECT sensor harness connector and ECM E4 connector. If temperature displayed on scan tool is not 284°F (140°C) or more, replace ECM and retest.
  4. Turn ignition off. Disconnect ECT sensor connector. Turn ignition on. If temperature displayed on scan tool is -40°F (-40°C), replace ECT sensor and retest. If temperature displayed is not -40°F (-40°C), turn ignition off and go to next step.
  5. Disconnect E4 connector from ECM. Turn ignition on. If temperature displayed is -40°F (-40°C), check for short in Red/Blue or Brown wire between ECT sensor and ECM E4 connector. If temperature displayed by scan tool is not -40°F (-40°C), replace ECM and retest.

Retrieve trouble codes. See RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. If other codes are displayed, diagnose and repair those codes first and retest. If only DTC P0116 is displayed, check thermostat. Replace as necessary. If thermostat is okay, replace ECT sensor and retest.

Diagnosis & Repair (Using Lexus Scan Tool)

  1. Connect Lexus scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Turn ignition on. Turn scan tool on. Using Lexus scan tool, monitor throttle valve opening percentage at VTA circuit and voltage at VTA2 circuit. Depress accelerator pedal to floor (WOT). Opening percentage should be 64-96 percent and voltage should be 4.6-5.1 volts with a fully open throttle. Release accelerator pedal. Opening percentage should be 8-20 percent and voltage should be 2.0-2.9 volts with a fully closed throttle. If readings are within specification, replace ECM and retest. If readings are not within specification, go to next step.
  2. Access ECM at left front of engine compartment. Turn ignition on. Backprobing connector, measure voltage between ECM E5 connector terminals No. 23 (Blue/Red wire) and No. 22 (Brown wire). (Scheme 67) If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, replace ECM and retest.
  3. Turn ignition on. Backprobing connector, measure voltage between terminals No. 22 (Brown wire) and No. 25 (Yellow wire) at ECM E5 connector. Voltage should be.4-1.0 volt with throttle fully closed and 3.2-4.8 volts with throttle fully open. Backprobing connector, measure voltage between terminals No. 22 (Brown wire) and No. 24 (Blue/Black wire) at ECM E5 connector. Voltage should be 2.0-2.9 volts with throttle fully closed and 4.6-5.1 volts with throttle fully open. If voltage is not as specified, go to next step. If voltage is as specified, replace ECM and retest.
  4. Check TP sensor operation. See appropriate SYSTEM & COMPONENT TESTING article. Replace TP sensor as necessary. If TP sensor is okay, check for short or open circuits in wiring harness and sensor connector between ECM E5 connector and TP sensor.

Diagnosis & Repair (Using OBD-II Scan Tool)

  1. Access ECM at left front of engine compartment. Turn ignition on. Backprobing connector, measure voltage between ECM E5 connector terminals No. 22 (Brown wire) and No. 23 (Blue/Red wire). (Scheme 67) If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, replace ECM and retest.
  2. Turn ignition on. Backprobing connector, measure voltage between terminals No. 22 (Brown wire) and No. 25 (Yellow wire) at ECM E5 connector. Voltage should be.4-1.0 volt with throttle fully closed and 3.2-4.8 volts with throttle fully open. Backprobing connector, measure voltage between terminals No. 22 (Brown wire) and No. 24 (Blue/Black wire) at ECM E5 connector. Voltage should be 2.0-2.9 volts with throttle fully closed and 4.6-5.1 volts with throttle fully open. If voltage is not as specified, go to next step. If voltage is as specified, replace ECM and retest.
  3. Check TP sensor operation. See appropriate SYSTEM & COMPONENT TESTING article. Replace TP sensor as necessary. If TP sensor is okay, check for short or open circuit in wiring harness and sensor connector between ECM E5 connector and TP sensor. See WIRING DIAGRAMS article. Repair as necessary.

Replace TP sensor and retest.

  1. Retrieve trouble codes. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22522-S10006286822001010300000) under SELF-DIAGNOSTIC SYSTEM. If any other codes are displayed other than DTC P0125, diagnose and repair those codes first. If only DTC P0125 is displayed, go to next step.
  2. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Start engine and warm to normal operating temperature. Using scan tool, monitor bank No. 1, sensor No. 1 and bank No. 2, sensor No. 1. Snap accelerate engine 3 times to 4000 RPM. Sensors should indicate a rich signal (.45 volt or more) at least once. If a rich signal is indicated for both sensors, go to step 9. If either sensor does not display a rich signal, go to next step.
  3. Check for open or short circuit in wiring harness between ECM and suspect oxygen sensor. See WIRING DIAGRAMS article. Repair wiring as necessary. If wiring harness is okay, go to next step.
  4. Check for misfire. See «DTC P0300: RANDOM CYLINDER MISFIRE DETECTED»(ref-22522-S18238741332001010300000). Repair as necessary and retest system. If misfire is not detected, go to next step.
  5. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, go to next step.
  6. Check fuel pressure. See FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article. If fuel pressure is not within specification, repair as necessary. If fuel pressure is within specification, go to next step.
  7. Check fuel injectors. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  8. Check exhaust system for leaks. If problem exists, repair as necessary. If problem does not exist, replace defective heated oxygen sensor.
  9. Perform test drive confirmation, then go to next step. See «TEST DRIVE CONFIRMATION»(ref-22522-S08314066462001010300000).
  10. Clear and recheck for DTCs. If DTC P0125 is displayed again, replace ECM. If DTC P0125 is not displayed again, go to next step.
  11. Vehicle either ran out of fuel or problem is intermittent. Check component and ECM connections.

Test Drive Confirmation

Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 If using Lexus scan tool, switch to CHECK mode. On both scan tools, start and warm engine to normal operating temperature. Allow engine to idle for 100 seconds or more. Drive vehicle at 24 MPH or more for 20 seconds. Stop vehicle and allow to idle for 20 seconds. Repeat driving and idle part of test 2 more times. At last idle test, allow to idle for 30 seconds. If using OBD-II scan tool, turn engine off. Repeat this procedure. If using either scan tool, if malfunction exists, MIL will illuminate.

  1. Drain cooling system. Remove and test thermostat. Replace thermostat as necessary. If thermostat is okay, install thermostat and refill cooling system. Go to next step.
  2. If any other DTCs are displayed, diagnose and repair those DTCs first and retest system. If only DTC P0128 is displayed, replace ECM and retest system.
  1. Retrieve trouble codes. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22522-S10006286822001010300000) under SELF-DIAGNOSTIC SYSTEM. If any other codes are displayed other than DTC P0130 or P0150, diagnose and repair those codes first. If only DTC P0130 or P0150 is displayed, go to next step.
  2. Start engine and raise engine speed to 2500 RPM for approximately 90 seconds. Let engine idle. Using scan tool, monitor each heated oxygen sensor No. 1 output voltage. Voltage should alternate repeatedly between less than .4 volt and more than .55 volt. If voltage is as specified, go to step 7 . If voltage is not as specified, go to next step.
  3. Check for open or short circuit in wiring harness between ECM and suspect heated oxygen sensor. See WIRING DIAGRAMS article. Repair wiring as necessary. If wiring harness is okay, go to next step.
  4. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, go to next step.
  5. Check fuel pressure. See FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article. If fuel pressure is not within specification, repair as necessary. If fuel pressure is within specification, go to next step.
  6. Check fuel injectors. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. If problem exists, repair as necessary. If problem does not exist, replace suspect heated oxygen sensor.
  7. Perform test drive confirmation, then go to next step. See «TEST DRIVE CONFIRMATION»(ref-22522-S09426287872001010300000) .
  8. Clear and recheck for DTCs. If DTC P0130 or P0150 is displayed again, replace ECM. If DTC P0130 or P0150 is not displayed again, problem is intermittent. Check component and ECM connections.

Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 If using Lexus scan tool, switch to CHECK mode. On both scan tools, start and warm engine to normal operating temperature. Allow engine to idle for 100 seconds or more. Drive vehicle at 24 MPH or more for 20 seconds. Stop vehicle and allow to idle for 20 seconds. Repeat driving and idle part of test 2 more times. At last idle test, allow to idle for 30 seconds. If using OBD-II scan tool, turn engine off. Repeat this procedure. If using either scan tool, if malfunction exists, MIL will illuminate.

  1. Retrieve trouble codes. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22522-S10006286822001010300000) under SELF-DIAGNOSTIC SYSTEM. If any other codes are displayed other than DTC P0133 or P0153, diagnose and repair those codes first. If only DTC P0133 or P0153 is displayed, go to next step.
  2. Start engine and raise engine speed to 2500 RPM for approximately 90 seconds. Let engine idle. Using scan tool, monitor each heated oxygen sensor No. 1 output voltage. Voltage should alternate repeatedly between less than .4 volt and more than .55 volt. If voltage is as specified, go to step 7 . If voltage is not as specified, go to next step.
  3. Check for open or short circuit in wiring harness between ECM and suspect heated oxygen sensor. See WIRING DIAGRAMS article. Repair wiring as necessary. If wiring harness is okay, go to next step.
  4. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, go to next step.
  5. Check fuel pressure. See FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article. If fuel pressure is not within specification, repair as necessary. If fuel pressure is within specification, go to next step.
  6. Check fuel injectors. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. If problem exists, repair as necessary. If problem does not exist, replace suspect heated oxygen sensor.
  7. Perform test drive confirmation, then go to next step. See «TEST DRIVE CONFIRMATION»(ref-22522-S19396285562001010300000) .
  8. Clear and recheck for DTCs. If DTC P0133 or P0153 is displayed again, replace ECM. If DTC P0133 or P0153 is not displayed again, problem is intermittent. Check component and ECM connections.

Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 If using Lexus scan tool, switch to CHECK mode. On both scan tools, start and warm engine to normal operating temperature. Allow engine to idle for 100 seconds or more. Drive vehicle at 24 MPH or more for 20 seconds. Stop vehicle and allow to idle for 20 seconds. Repeat driving and idle part of test 2 more times. At last idle test, allow to idle for 30 seconds. If using OBD-II scan tool, turn engine off. Repeat this procedure. If using either scan tool, if malfunction exists, MIL will illuminate.

  1. Access ECM at left front of engine compartment. Turn ignition on. Using DVOM, backprobe ECM harness connector. Measure voltage between ground and following ECM terminal: For DTC P0135, terminal No. 9 (Blue/Yellow wire) of ECM connector E6. For DTC P0141, terminal No. 7 (Black/White wire) of ECM connector E2. For DTC P0155, terminal No. 30 (Green/Yellow wire) of ECM connector E4. For DTC P0161, terminal No. 8 (Gray wire) of ECM connector E2. For ECM terminal identification (Scheme 67) Voltage should be 9-14 volts at each terminal. If voltage is as specified, replace ECM. If voltage is not as specified, go to next step.
  2. Disconnect suspect heated oxygen sensor harness connector. Measure resistance between following heated oxygen sensor connector terminals B+ and HT (component side): For DTC P0135, bank No. 1 sensor No. 1, measure resistance between White and Blue/Yellow wires. For DTC P0141, bank No. 1 sensor No. 2, measure resistance between White and Black/White wires. For DTC P0155, bank No. 2 sensor No. 1, measure resistance between White and Green/Yellow wires. For DTC P0161, bank No. 1 sensor No. 1, measure resistance between White and Gray wires. Resistance should be 11-16 ohms at 68°F (20°C). If resistance is not as specified, replace appropriate heated oxygen sensor. If resistance is as specified, go to next step.
  3. Repair wiring between ECM and appropriate heated oxygen sensor or between appropriate heated oxygen sensor and EFI main relay. See WIRING DIAGRAMS article.
  1. Retrieve trouble codes. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22522-S10006286822001010300000) under SELF-DIAGNOSTIC SYSTEM. If any other codes are displayed other than DTC P0136 or P0156, diagnose and repair those codes first. If only DTC P0136 or P0156 are displayed, go to next step.
  2. Check for open or short circuit in wiring harness between ECM and suspect oxygen sensor. See WIRING DIAGRAMS article. Repair wiring as necessary. If wiring harness is okay, go to next step.
  3. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Start and warm engine to normal operating temperature. Monitor bank No. 1 and No. 2, sensor No. 2. Raise engine speed to 2500 RPM for 3 minutes. Return engine to idle. Quickly raise engine speed to 4000 RPM 3 times. Voltage should fluctuate from.4 volt or less to.5 volt or more. If voltage responds correctly, check wiring harness connections. Problem may be intermittent. If voltage does not respond correctly, replace appropriate oxygen sensor and retest.
  1. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, go to next step.
  2. Check fuel injectors. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  3. Check Mass Airflow (MAF) meter and Engine Coolant Temperature (ECT) sensor. See ENGINE SENSORS & SWITCHES in appropriate SYSTEM & COMPONENT TESTING article. If problem exists, replace appropriate sensor(s). If problem does not exist, go to next step.
  4. Check spark and ignition system. See IGNITION CHECKS in BASIC DIAGNOSTIC PROCEDURES article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  5. Check fuel pressure. See FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article. If fuel pressure is not within specification, repair as necessary. If fuel pressure is within specification, go to next step.
  6. Check exhaust system for leaks. If problem exists, repair as necessary. If problem does not exist, go to next step.
  7. Connect scan tool to Data Link Connector (DLC) No. 3. Start engine and raise engine speed to 2500 RPM for approximately 90 seconds. Let engine idle. Using scan tool, monitor each heated oxygen sensor No. 1 output voltage. Voltage should alternate repeatedly between less than .4 volt to more than .55 volt. If voltage is as specified, go to step 9 . If voltage is not as specified, go to next step.
  8. Check for open or short in wiring between ECM and suspect heated oxygen sensor No. 1. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace appropriate heated oxygen sensor No. 1.
  9. Perform test drive confirmation, then go to next step. See «TEST DRIVE CONFIRMATION»(ref-22522-S15564682252001010300000) .
  10. Clear and recheck for DTCs. If DTCs P0171, P0172 P0174 or P0175 are displayed again, replace ECM. If DTCs P0171, P0172 P0174 or P0175 are not displayed, go to next step.
  11. Vehicle either ran out of fuel or problem is intermittent. Check component and ECM connections.

Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 If using Lexus scan tool, switch to CHECK mode. On both scan tools, start and warm engine to normal operating temperature. Allow engine to idle for 100 seconds or more. Drive vehicle at 24 MPH or more for 20 seconds. Stop vehicle and allow to idle for 20 seconds. Repeat driving and idle part of test 2 more times. At last idle test, allow to idle for 30 seconds. If using OBD-II scan tool, turn engine off. Repeat this procedure. If using either scan tool, if malfunction exists, MIL will illuminate.

Circuit Description

ECM uses signals provided by crankshaft and camshaft position sensors. If engine speed rate has changed enough to equal a preset number, a misfire is detected and MIL is illuminated. If misfire rate is high enough, and driving conditions will cause catalytic converter damage or overheating, MIL blinks when a misfire is occurring. DTC is set when misfiring of random cylinders is detected during any particular 200 or 1000 revolutions. Possible causes are

  1. Open or short in wiring.
  2. Poor connector contact at ECM.
  3. Vacuum hose leaking or misrouted.
  4. Faulty ignition system.
  5. Faulty fuel injector(s).
  6. Improper fuel pressure.
  7. Faulty Mass Airflow (MAF) meter.
  8. Faulty Engine Coolant Temperature (ECT) sensor.
  9. Faulty engine compression.
  10. Improper valve clearance.
  11. Improper valve timing.
  12. Faulty ECM.

Diagnostic Aids

When 2 or more codes for a misfiring cylinder are recorded repeatedly, but DTC P0300 is not recorded, it indicates that misfires were detected and stored into ECM memory at different times. If misfire cannot be reproduced, reason may be because of driving with lack of fuel, improper fuel, fouled spark plug, etc. Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.

  1. Check vacuum hoses for leaks, blockage and proper routing. Also, check wiring and connectors for damage or poor connections. If problem exists, repair as necessary and perform «TEST DRIVE CONFIRMATION»(ref-22522-S31549528062001010300000). If problem does not exist, go to next step.
  2. Check spark and ignition system. See IGNITION CHECKS in BASIC DIAGNOSTIC PROCEDURES article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  3. Access ECM at left front of engine compartment. Turn ignition on. Using DVOM, backprobe ECM connector and measure voltage between ground and fuel injector terminals at specified ECM connector. See «IDENTIFYING FUEL INJECTOR TERMINALS»(ref-22522-S18107766382001010300000) table. (Scheme 67) If voltage is 9-14 volts at each terminal, go to step 5. If voltage is not 9-14 volts at each terminal, go to next step. IDENTIFYING FUEL INJECTOR TERMINALS Fuel Injector No. Terminal No. Wire Color 1 15 (1) Blue 2 17 (2) White 3 14 (1) Green/Yellow 4 16 (2) Green 5 13 (1) Green 6 15 (2) Brown 7 12 (1) Brown 8 14 (2) Yellow/Black (1) Terminal is located in ECM harness connector E5. (Scheme 67) (2) Terminal is located in ECM harness connector E4. (Scheme 67)
  4. Disconnect fuel injector harness connector at misfiring cylinder. Measure resistance between fuel injector terminals (component side). Resistance should be 13.4-14.2 ohms at 68°F (20°C). If resistance is as specified, repair open or short in power circuit to fuel injector or in wiring harness between ECM and fuel injector. See WIRING DIAGRAMS article. If resistance is not as specified, replace fuel injector.
  5. Check fuel pressure. See FUEL SYSTEM in BASIC DIAGNOSTIC PROCEDURES article. If fuel pressure is not within specification, repair as necessary. If fuel pressure is within specification, go to next step.
  6. Check fuel injectors. See FUEL SYSTEM in appropriate SYSTEM & COMPONENT TESTING article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  7. Check Mass Airflow (MAF) meter and Engine Coolant Temperature (ECT) sensor. See ENGINE SENSORS & SWITCHES in appropriate SYSTEM & COMPONENT TESTING article. If problem exists, replace appropriate sensor(s). If problem does not exist, go to next step.
  8. Check engine compression. See BASIC DIAGNOSTIC PROCEDURES article. If engine compression is okay, check valve clearance. See ON-VEHICLE ADJUSTMENTS article. If valve clearance is okay, it may be necessary to check valve timing. See appropriate article in ENGINES.
  1. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Record any DTCs and freeze frame data. Switch scan tool to CHECK mode (Lexus scan tool only). 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 scan tool data list.
  2. Drive vehicle at specified engine speeds. See «DRIVING PATTERN»(ref-22522-S31091641602001010300000) table. Turn ignition off after symptom is simulated the first time, then repeat test drive again (OBD-II scan tool only). 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 (1) Minutes Idling 3 1/2 1000 3 2000 1 1/2 3000 1 (1) Minimum specification given.

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

  1. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Disconnect EC1 Black 3-pin connector. EC1 connector is a wire-to-wire connector located at center rear of engine, near starter. Using a fused jumper wire, connect terminal No. 3 (Gray wire) on male part of connector to terminal No. 2 (Black wire) on female part of connector. Connect another jumper wire between terminal No. 2 (Black wire) on male part of connector to terminal No. 3 (White wire) on female part of connector.
  2. Turn ignition on. Turn scan tool on. Allow engine to reach its normal operating temperature. Snap throttle 3 times to 4000 RPM. Retrieve trouble codes. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22522-S10006286822001010300000) under SELF-DIAGNOSTIC SYSTEM. If same DTC is repeated, go to next step. If DTC changed, go to step 4.
  3. Check for short or open in Black or White wires between EC1 harness connector and ECM. Repair as necessary. If wiring harness is okay, replace ECM.
  4. Check for short or open in Black or Gray wires between EC1 harness connector and knock sensor. Repair as necessary. If wiring harness is okay, replace knock sensor.

The Crankshaft Position (CKP) sensor consists of a pick-up coil and signal plate. CKP sensor is located on oil pump body. Signal plate has 34-teeth and is mounted on timing belt guide. DTC P0335 is set if no signal is received by ECM from CKP sensor while cranking. DTC P0335 is also set if no signal is received by ECM from CKP sensor with engine speed of 450 RPM of more. DTC P1335 is set if no signal is received by ECM from CKP sensor with engine speed of 1000 RPM or more. Possible causes are

  1. CKP sensor open or short circuit.
  2. Faulty CKP sensor.
  3. Faulty signal plate.
  4. Faulty ECM.

Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.

  1. Disconnect CKP sensor connector. Using ohmmeter, measure resistance between CKP sensor terminals. Resistance should be 1630-2740 ohms with engine temperature at 14-122°F (-10-50°C) or 2065-3225 ohms with engine temperature at 122-212°F (50-100°C). If resistance is as specified, go to next step. If resistance is not as specified, replace CKP sensor.
  2. Check for short or open circuit in wiring harness between ECM E5 connector and CKP sensor. See WIRING DIAGRAMS article. Repair wiring as necessary. If wiring harness is okay, go to next step.
  3. Check CKP sensor for proper installation. Also inspect signal plate. Repair or replace as necessary. If CKP sensor and signal plate are okay, replace ECM and retest.

The CMP sensor consists of a one-tooth signal plate and a pick-up coil. Sensor is mounted in No. 3 timing belt cover in left front of engine. Signal plate is mounted to front of left bank camshaft. DTC P0340 is set when no camshaft position signal is received by ECM from CMP sensor during cranking. DTC P0340 is also set when no camshaft position signal is received by ECM from CMP sensor with engine speed of 600 RPM or more. Possible causes are

  1. Open or short in CMP sensor circuit.
  2. Faulty CMP sensor.
  3. Faulty left bank camshaft pulley.
  4. Faulty ECM.

Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.

  1. Disconnect CMP sensor harness connector. Measure resistance between CMP sensor connector terminals (component side). Resistance should be 835-1400 ohms with engine temperature at 14-122°F (-10-50°C), or 1060-1645 ohms with engine temperature at 122-212°F (50-100°C). If resistance is as specified, go to next step. If resistance is not as specified, replace CMP sensor.
  2. Check for short or open circuit in wiring harness between ECM E5 connector and CMP sensor. See WIRING DIAGRAMS article. Repair wiring as necessary. If wiring harness is okay, go to next step.
  3. Remove and inspect CMP sensor. Also inspect signal plate. If problem exists, replace CMP sensor and/or signal plate as necessary. If problem does not exist, replace ECM.
  1. Retrieve trouble codes. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22522-S10006286822001010300000) under SELF-DIAGNOSTIC SYSTEM. If only DTC P0420 or P0430 is displayed, go to next step. If other codes are displayed, diagnose and repair those codes first and retest.
  2. Check for exhaust leaks. Repair as necessary. If exhaust system is okay, check heated oxygen sensor circuits (bank No. 1, sensor No. 1 and bank No. 2, sensor No. 1). See «DTC P0130 OR DTC P0150: HEATED OXYGEN SENSOR CIRCUIT MALFUNCTION»(ref-22522-S40970981442001010300000) test. Repair as necessary. If no problems are indicated, go to next step.
  3. Check heated oxygen sensor circuits (bank No. 1, sensor No. 2 and bank No. 2, sensor No. 2). See «DTC P0136 OR P0156: HEATED OXYGEN SENSOR CIRCUIT MALFUNCTION»(ref-22522-S40502618302001010300000) test. Repair as necessary. If oxygen sensor circuits are okay, replace catalytic converter and retest.
  1. Check with vehicle driver if fuel tank cap was found loose at any time. If fuel tank cap was loose, it probably was cause of DTC P0440 setting. If fuel tank cap was not loose, check for cracks, deformations or loose connections in following: Fuel tank. Charcoal canister. Fuel tank filler pipe. Hose and tubes around fuel tank and charcoal canister. Repair as necessary. If components are okay, go to next step.
  2. Check if fuel tank cap is an original manufacturer's cap. If fuel tank cap is an original manufacturer's cap, go to next step. If fuel tank cap is not an original manufacturer's cap, replace cap with a manufacturer's cap.
  3. Check if fuel cap is installed properly. Reinstall cap as necessary. If fuel cap is installed properly, go to next step.
  4. Check for damaged fuel tank cap and gasket. Replace fuel cap as necessary. If fuel tank cap and gasket are okay, go to next step.
  5. Remove fuel tank cap. Visually inspect fuel tank filler neck for damage. Replace filler neck as necessary. If filler neck is okay, go to next step.
  6. Check vacuum hoses between vapor pressure sensor and fuel tank, and between pressure switching valve VSV and charcoal canister. Check hoses for correct installation, looseness and damage. Repair as necessary. If vacuum hoses are okay, go to next step.
  7. Check hose and tube between fuel tank and charcoal canister for correct installation and damage. Repair as necessary. If hose and tube are okay, go to next step.
  8. Visually inspect charcoal canister for cracks or damage. Replace canister as necessary. If canister is okay, go to next step.
  9. Access ECM at left front of engine compartment. Turn ignition on. Backprobing connector, measure voltage between terminals No. 27 (Orange wire) and No. 26 (Brown/White wire) at ECM E2 connector. (Scheme 67) If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, replace ECM and retest system. NOTE: DO NOT apply more than 19.7 in. Hg of vacuum to vapor pressure sensor.
  10. Backprobing ECM harness connector, measure voltage between terminals No. 25 (Green/Red wire) and No. 26 (Brown/White wire) at ECM E2 connector. Disconnect vacuum supply hose (hose closest to electrical connector) from vapor pressure sensor. Sensor is mounted on charcoal canister and is located next to fuel tank. Connect a vacuum pump to sensor. If voltage is 2.9-3.7 volts without vacuum applied, and.5 volt or less with 1.2 in. Hg of vacuum applied, go to step 12. If voltage is not as specified, go to next step.
  11. Check for an open or short circuit in wiring harness between vapor pressure sensor and ECM. See WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace vapor pressure sensor.
  12. Fuel tank or fuel tank overfill check valve may be defective. Check fuel evaporation system. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. Repair as necessary. If no problem is indicated, probable cause of DTC P0440 to set was an incorrectly installed fuel tank cap.
  1. Check for cracks, deformations or loose connections in following: Fuel tank. Charcoal canister. Fuel tank filler pipe. Hose and tubes around fuel tank and charcoal canister. Repair as necessary. If components are okay, go to next step.
  2. Check if fuel tank cap is an original manufacturer's cap. If fuel tank cap is an original manufacturer's cap, go to next step. If fuel tank cap is not an original manufacturer's cap, replace cap with a manufacturer's cap.
  3. Check if fuel cap is installed properly. Reinstall cap as necessary. If fuel cap is installed properly, go to next step.
  4. Check for damaged fuel tank cap and gasket. Replace fuel tank cap as necessary. If fuel tank cap and gasket are okay, go to next step.
  5. Remove fuel tank cap. Visually inspect fuel tank filler neck for damage. Replace filler neck as necessary. If filler neck is okay, go to next step.
  6. Check vacuum hoses between vapor pressure sensor and fuel tank, and between pressure switching valve VSV and charcoal canister. Check hoses for correct installation, looseness and damage. Repair as necessary. If vacuum hoses are okay, go to next step.
  7. Check hose and tube between fuel tank and charcoal canister for correct installation and damage. Repair as necessary. If hose and tube are okay, go to next step.
  8. Check EVAP VSV, canister closed valve VSV, pressure switching valve VSV and vapor pressure sensor wiring harness connectors for damaged pins, corrosion and loose wires. Repair as necessary. If connectors are okay, go to next step. For component locations, see appropriate illustration in THEORY & OPERATION article.
  9. Check all EVAP related vacuum hoses between fuel tank and charcoal canister, and between fuel tank and fuel tank overfill check valve for damage, blockage, looseness and correct routing. Repair as necessary. If vacuum hoses are okay, go to next step. For proper vacuum hose routing, see appropriate illustration in VACUUM DIAGRAMS article.
  10. Access ECM at left front of engine compartment. Turn ignition on. Backprobing connector, measure voltage between terminals No. 27 (Orange wire) and No. 26 (Brown/White wire) at ECM E2 connector. (Scheme 67) If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, replace ECM and retest system. NOTE: DO NOT apply more than 19.7 in. Hg of vacuum to vapor pressure sensor.
  11. Backprobing ECM harness connector, measure voltage between terminals No. 25 (Green/Red wire) and No. 26 (Brown/White wire) at ECM E2 connector. Disconnect vacuum supply hose (hose closest to electrical connector) from vapor pressure sensor. Sensor is mounted on charcoal canister and is located next to fuel tank. Connect a vacuum pump to sensor. If voltage is 2.9-3.7 volts without vacuum applied, and.5 volt or less with 1.2 in. Hg of vacuum applied, go to step 13. If voltage is not as specified, go to next step.
  12. Check for an open or short circuit in wiring harness and connector between vapor pressure sensor and ECM. See WIRING DIAGRAMS article. Repair as necessary. If wiring harness and connector are okay, replace vapor pressure sensor and retest.
  13. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Using scan tool, select ACTIVE TEST mode. Disconnect vacuum hose from charcoal canister at EVAP VSV. (Scheme 68) Start engine. Using scan tool, activate EVAP VSV. When EVAP VSV is activated, vacuum should be present. When EVAP VSV is not activated, no vacuum should be present. If vacuum is as specified, go to step 17. If vacuum is not as specified, go to next step.
  14. Turn ignition off. Check for correct routing, damage, looseness and blockage in vacuum hoses between throttle body and EVAP VSV, and between EVAP VSV and charcoal canister. Repair as necessary. If vacuum hoses are okay, go to next step.
  15. Check EVAP VSV. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If EVAP VSV is not okay, replace EVAP VSV and charcoal canister. Also clean vacuum hoses between throttle body and EVAP VSV, and EVAP VSV and charcoal canister. If EVAP VSV is okay, go to next step.
  16. Check for open or short circuit in wiring harness and connector between EFI main relay, EVAP VSV and ECM. See WIRING DIAGRAMS article. Repair as necessary. If wiring harness and connector are okay, replace ECM and retest.
  17. Turn ignition off. Disconnect canister closed valve VSV vacuum hose. VSV is mounted on back of intake air baffle and has a Black 2-pin connector with White and Yellow wires. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Turn ignition on. Select ACTIVE TEST mode on scan tool. Using scan tool, turn canister closed valve VSV on. Air should not flow through canister closed valve VSV. Using scan tool, turn canister closed valve VSV off. Air should now flow through canister closed valve VSV. If VSV operates correctly, go to step 20. If VSV does not operate correctly, go to next step.
  18. Check canister closed valve VSV. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If canister closed valve VSV is not okay, replace canister closed valve VSV and charcoal canister. Also clean vacuum hoses between charcoal canister and canister closed valve VSV. If canister closed valve VSV is okay, check vacuum hose between canister closed valve VSV and charcoal canister for looseness, damage and blockage. Replace vacuum hose as necessary. If vacuum hose is okay, go to next step.
  19. Check for an open or short in wiring harness between EFI main relay, canister closed valve VSV and ECM. See WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace ECM and retest system.
  20. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Ensure ignition is on. Select ACTIVE TEST mode on scan tool. Locate pressure switching valve VSV on charcoal canister, mounted next to fuel tank. Pressure switching valve VSV has 2 vacuum ports and a Blue 2-pin connector with White and Black/Blue wires. Disconnect vacuum hoses from pressure switching valve VSV. Using scan tool, activate pressure switching valve VSV. Apply compressed air to port "E" of pressure switching valve VSV. Air should flow from port "F". (Scheme 69) Using scan tool, turn pressure switching valve VSV off. Air should not flow from port "F". If VSV operates correctly, go to step 23. If VSV does not operate correctly, go to next step.
  21. Check pressure switching valve VSV. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If pressure switching valve VSV is not okay, replace pressure switching valve VSV and charcoal canister. Also clean vacuum hose between charcoal canister and pressure switching valve VSV, and between pressure switching valve VSV and fuel tank. If pressure switching valve VSV is okay, go to next step.
  22. Check for an open or short in wiring harness between EFI main relay, pressure switching valve VSV and ECM. See WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace ECM and retest system.
  23. Access ECM under protective cover, behind left headlight in engine compartment. Backprobing ECM harness connector, connect DVOM between terminal No. 25 (Green/Red wire) and terminal No. 26 (Brown/White wire) at ECM E2 connector. (Scheme 67) Select ACTIVE TEST mode on scan tool. Start engine. EVAP VSV, canister closed valve VSV and pressure switching valve VSV should all be on. Observing DVOM, when voltage reaches 1.2 volts, switch EVAP VSV and pressure switching valve VSV off. (Scheme 70) Wait 30 seconds and note DVOM voltage reading. If voltage stays at 1.2 volts, fuel tank is okay. Go to next step. If voltage does not stay at 1.2 volts, replace fuel tank.
  24. Access ECM at left front of engine compartment. Backprobing ECM harness connector, connect DVOM between terminal No. 25 (Green/Red wire) and terminal No. 26 (Brown/White wire) at ECM E2 connector. (Scheme 67) Select ACTIVE TEST mode on scan tool. Start engine. EVAP VSV, canister closed valve VSV and pressure switching valve VSV should all be on. Observing DVOM, when voltage reaches 1.2 volts, switch EVAP VSV off. (Scheme 71) Wait 30 seconds and note DVOM voltage reading. If voltage stays at 1.2 volts, go to next step. If voltage does not stay at 1.2 volts, replace charcoal canister.
  25. Charcoal canister or fuel tank overfill check valve maybe defective. Check fuel evaporation system. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. Repair as necessary. If no problem is indicated, replace charcoal canister.

Scheme 68

Scheme 68
Scheme 68

Scheme 69

Scheme 69
Scheme 69

Scheme 70

Scheme 70
Scheme 70

Scheme 71

Scheme 71
Scheme 71

Scheme 72

Scheme 72: Diagnosis & Repair (Using OBD-II Scan Tool)
Scheme 72: Diagnosis & Repair (Using OBD-II Scan Tool)
  1. Check for cracks, deformations or loose connections in following: Fuel tank. Charcoal canister. Fuel tank filler pipe. Hose and tubes around fuel tank and charcoal canister. Repair as necessary. If components are okay, go to next step.
  2. Check if fuel tank cap is an original manufacturer's cap. If fuel tank cap is an original manufacturer's cap, go to next step. If fuel tank cap is not an original manufacturer cap, replace cap with a manufacturer's cap.
  3. Check if fuel cap is installed properly. Reinstall cap as necessary. If fuel cap is installed properly, go to next step.
  4. Check for damaged fuel tank cap and gasket. Replace fuel tank cap as necessary. If fuel tank cap and gasket are okay, go to next step.
  5. Remove fuel tank cap. Visually inspect fuel tank filler neck for damage. Replace filler neck as necessary. If filler neck is okay, go to next step.
  6. Check vacuum hoses between vapor pressure sensor and fuel tank, and between pressure switching valve VSV and charcoal canister. Check hoses for correct installation, looseness and damage. Repair as necessary. If vacuum hoses are okay, go to next step.
  7. Check hose and tube between fuel tank and charcoal canister for correct installation and damage. Repair as necessary. If hose and tube are okay, go to next step.
  8. Check EVAP VSV, canister closed valve VSV, pressure switching valve VSV and vapor pressure sensor wiring harness connectors for damaged pins, corrosion and loose wires. Repair as necessary. If connectors are okay, go to next step. For component locations, see appropriate illustration in THEORY & OPERATION article.
  9. Check all EVAP related vacuum hoses between fuel tank and charcoal canister, and between fuel tank and fuel tank overfill check valve for damage, blockage, looseness and correct routing. Repair as necessary. If vacuum hoses are okay, go to next step. For proper vacuum hose routing, see appropriate illustration in VACUUM DIAGRAMS article.
  10. Turn ignition on. Backprobing connector, measure voltage between terminals No. 27 (Orange wire) and No. 26 (Brown/White wire) at ECM E2 connector. (Scheme 67) If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, replace ECM and retest system. NOTE: DO NOT apply more than 19.7 in. Hg of vacuum to vapor pressure sensor.
  11. Backprobing ECM harness connector, measure voltage between terminals No. 25 (Green/Red wire) and No. 26 (Brown/White wire) at ECM E2 connector. Disconnect vacuum supply hose (hose closest to electrical connector) from vapor pressure sensor. Sensor is mounted on charcoal canister and is located next to fuel tank. Connect a vacuum pump to sensor. If voltage is 2.9-3.7 volts without vacuum applied, and.5 volt or less with 1.2 in. Hg of vacuum applied, go to step 13. If voltage is not as specified, go to next step.
  12. Check for an open or short circuit in wiring harness and connector between vapor pressure sensor and ECM. See WIRING DIAGRAMS article. Repair as necessary. If wiring harness and connector are okay, replace vapor pressure sensor and retest.
  13. Turn ignition on. Disconnect EVAP VSV vacuum hoses. VSV is located on top of air intake chamber, near PCV valve. Backprobing connector, connect fused jumper wire between ground and terminal No. 11 (Green/Black wire) at ECM E5 connector. Apply compressed air to EVAP VSV port "E". (Scheme 72) Air should flow from port "F". Disconnect fused jumper wire. Air should not flow from port "F". If EVAP VSV does not function as specified, go to next step. If EVAP VSV functions as specified, go to step 16.
  14. Remove EVAP VSV. Using ohmmeter, measure resistance between VSV terminals. With VSV temperature at 68°F (20°C), resistance should be 30-34 ohms. Measure resistance between each terminal and body of valve. Resistance should be infinite. If resistance is as specified, using fused jumper wires, apply battery voltage and ground to EVAP VSV terminals. Apply compressed air to EVAP VSV port "E". Air should flow from port "F". (Scheme 72) Disconnect fused jumper wires. Air should not flow from port "F". If EVAP VSV does not operate as specified, or if resistance was not as specified, replace EVAP VSV and charcoal canister. After replacing components, clean vacuum hoses between EVAP VSV and throttle body, and between EVAP VSV and charcoal canister. If EVAP VSV operates as specified, go to next step.
  15. Check for open or short circuit in wiring harness and connector between EFI main relay, EVAP VSV and ECM. See WIRING DIAGRAMS article. Repair as necessary. If wiring harness is okay, replace ECM and retest.
  16. Turn ignition off. Disconnect canister closed valve VSV vacuum hose. VSV is mounted on back of intake air baffle and has a Black 2-pin connector with White and Yellow wires. Access ECM under protective cover, behind left headlight in engine compartment. Turn ignition on. Backprobing connector, connect a fused jumper wire between ground and terminal No. 22 (Red wire) at ECM E4 connector. (Scheme 67) Air should not flow through canister closed valve VSV. Disconnect fused jumper wire. Air should flow through canister closed valve VSV. If VSV does not function as specified, go to next step. If VSV functions as specified, go to step 19.
  17. Check canister closed valve VSV. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If VSV is okay, go to next step. If VSV is not okay, replace canister closed VSV and charcoal canister. Also clean vacuum hose between charcoal canister and canister closed valve VSV.
  18. Check for an open or short circuit in wiring harness between EFI main relay, canister closed valve VSV and ECM. See WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace ECM and retest system.
  19. Turn ignition on. Access ECM under protective cover, behind left headlight in engine compartment. Backprobing connector, connect a fused jumper wire between ground and terminal No. 10 (Black/Blue wire) at ECM E2 connector. (Scheme 67) Locate pressure switching valve VSV on charcoal canister, mounted next to tank. Pressure switching valve VSV has 2 vacuum ports and a Blue 2-pin connector with White and Black/Blue wires. Apply compressed air to port "E" of pressure switching valve VSV. Air should flow from port "F". (Scheme 69) Remove fused jumper wire. Air should not flow from port "F". If VSV functions as specified, go to step 22. If VSV does not function as specified, go to next step.
  20. Check pressure switching valve VSV. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If pressure switching valve VSV is not okay, replace pressure switching valve VSV and charcoal canister. Also clean vacuum hose between charcoal canister and pressure switching valve VSV, and between pressure switching valve VSV and fuel tank. If pressure switching valve VSV is okay, go to next step.
  21. Check for an open or short in wiring harness between EFI main relay, pressure switching valve VSV and ECM. See WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace ECM and retest system.
  22. Charcoal canister or fuel tank overfill check valve may be defective. Check fuel evaporation system. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. Repair as necessary.
  1. Access ECM at left front of engine compartment. Turn ignition on. Backprobing connector, measure voltage between terminals No. 27 (Orange wire) and No. 26 (Brown/White wire) at ECM E2 connector. (Scheme 67) If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, replace ECM and retest system. NOTE: DO NOT apply more than 19.7 in. Hg of vacuum to vapor pressure sensor.
  2. Backprobing ECM harness connector, measure voltage between terminals No. 25 (Green/Red wire) and No. 26 (Brown/White wire) at ECM E2 connector. Disconnect vacuum supply hose (hose closest to electrical connector) from vapor pressure sensor. Sensor is mounted on charcoal canister and is located next to fuel tank. Connect a vacuum pump to sensor. If voltage is 2.9-3.7 volts without vacuum applied, and.5 volt or less with 1.2 in. Hg of vacuum applied, replace ECM and retest system. If voltage is not as specified, go to next step.
  3. Check for an open or short circuit in wiring harness and connectors between vapor pressure sensor and ECM. See WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace vapor pressure sensor and retest system.
  1. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Turn ignition on. Turn scan tool on. Test drive vehicle and compare scan tool displayed speed with actual vehicle speed. If scan tool indicated speed matches actual vehicle speed, go to next step. If scan tool indicated speed does not match actual vehicle speed, replace ECM and retest system.
  2. Check speedometer operation. Repair speedometer circuit as necessary. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. If speedometer operation is okay, go to next step.
  3. Access ECM at left front of engine compartment. Disconnect ECM E6 connector. Using an ohmmeter, measure resistance between terminals No. 23 (Green wire) and No. 22 (Red wire) at ECM E6 connector. (Scheme 67) If resistance is 560-680 ohms, replace ECM and retest system. If resistance is not 560-680 ohms, go to next step.
  4. Remove VSS from rear of transmission. Using an ohmmeter, measure resistance between VSS connector terminals. Resistance should be 560-680 ohms. Using a voltmeter set to AC voltage, measure voltage between VSS connector terminals. Place a magnet close to front of VSS and quickly remove (to generate a voltage pulse). If voltage pulse is not generated, replace VSS and retest. If voltage pulse is generated, check wiring harness between VSS and ECM. See WIRING DIAGRAMS article. Repair wiring as necessary.
  1. Retrieve trouble codes. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22522-S10006286822001010300000) under SELF-DIAGNOSTIC SYSTEM. If only DTC P0505 is displayed, go to next step. If other codes are displayed, diagnose and repair those codes first and retest.
  2. Check for loose, damaged or cracked air intake hose between throttle body and air cleaner. Check for loose or damaged dipstick, oil fill cap or PCV hose. Repair as necessary. If all components are okay, go to next step.
  3. Check throttle control system. See THROTTLE CONTROLS in appropriate SYSTEM & COMPONENT TESTING article. Repair as necessary.
  1. Connect Lexus scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Turn ignition on. Turn scan tool on. Using Lexus scan tool, monitor accelerator pedal position sensor voltage at VPA and VPA2 circuits. Accelerator pedal position sensor voltage should be.5-1.1 volt at VPA circuit and.9-2.3 volts at VPA2 circuit with a fully closed throttle. Depress accelerator pedal to floor (WOT). Accelerator pedal position sensor voltage should be 3.0-4.6 volts at VPA circuit and 3.4-5.0 volts at VPA2 circuit with a fully open throttle. If voltages are within specification, replace ECM and retest. If voltages are not within specification, go to next step.
  2. Access ECM at left front of engine compartment. Turn ignition on. Backprobing connector, measure voltage between terminals No. 35 (Blue/Red wire) and No. 34 (Brown/Yellow wire) at ECM E2 connector. (Scheme 67) Measure voltage between terminals No. 27 (Orange wire) and No. 26 (Brown/White wire) at ECM E2 connector. If voltage reading is 4.5-5.5 volts at both circuits, go to next step. If voltage is not 4.5-5.5 volts at both circuits, replace ECM and retest.
  3. Backprobing connector, measure voltage between terminals No. 33 (Red/Yellow wire) and No. 26 (Brown/White wire) at ECM E2 connector. With fully closed throttle, voltage should be.5-1.1 volt. With Wide Open Throttle (WOT), voltage should be 3.0-4.6 volts. Measure voltage between terminals No. 34 (Brown/Yellow wire) and No. 32 (Red/Black wire) at ECM E2 connector. With fully closed throttle, voltage should be.9-2.3 volts. With WOT, voltage should be 3.4-5.0 volts. If voltage is not as specified, go to next step. If voltage is as specified, replace ECM and retest.
  4. Check accelerator pedal position sensor operation. See ENGINE SENSORS & SWITCHES in appropriate SYSTEM & COMPONENT TESTING article. Replace accelerator pedal position sensor as necessary. If accelerator pedal position sensor is okay, check for short or open circuit in wiring harness between ECM E2 connector and accelerator pedal position sensor. See WIRING DIAGRAMS article. Repair wiring as necessary.
  1. Access ECM at left front of engine compartment. Turn ignition on. Backprobing connector, measure voltage between terminals No. 35 (Blue/Red wire) and No. 34 (Brown/Yellow wire) at ECM E2 connector. (Scheme 67) Measure voltage between terminals No. 27 (Orange wire) and No. 26 (Brown/White wire) at ECM E2 connector. If voltage reading is 4.5-5.5 volts at both circuits, go to next step. If voltage is not 4.5-5.5 volts at both circuits, replace ECM and retest.
  2. Backprobing connector, measure voltage between terminals No. 33 (Red/Yellow wire) and No. 26 (Brown/White wire) at ECM E2 connector. With fully closed throttle, voltage should be.5-1.1 volt. With Wide Open Throttle (WOT), voltage should be 3.0-4.6 volts. Measure voltage between terminals No. 34 (Brown/Yellow wire) and No. 32 (Red/Black wire) at ECM E2 connector. With fully closed throttle, voltage should be.9-2.3 volts. With WOT, voltage should be 3.4-5.0 volts. If voltage is not as specified, go to next step. If voltage is as specified, replace ECM and retest.
  3. Check accelerator pedal position sensor operation. See ENGINE SENSORS & SWITCHES in appropriate SYSTEM & COMPONENT TESTING article. Replace accelerator pedal position sensor as necessary. If accelerator pedal position sensor is okay, check for short or open circuit in wiring harness between ECM E2 connector and accelerator pedal position sensor. See WIRING DIAGRAMS article. Repair wiring as necessary.

Replace accelerator pedal position sensor and retest.

Note. If using Lexus scan tool, go to step 1 . If not using Lexus scan tool, go to step 2 .

  1. Connect Lexus scan tool to DLC 3. see scheme 1 Turn ignition on. Turn scan tool on. Start engine and allow to idle. Monitor throttle motor current value on scan tool. If current draw is less than 7 amps, replace ECM and retest system. If current draw is 7 amps or more, go to step 3.
  2. Using an oscilloscope, Backprobing connector, connect oscilloscope between terminal No. 7 (Brown wire) at ECM E6 connector and terminal No. 3 (Black wire, M+ circuit) or No.2 (White wire, M- circuit) at ECM E5 connector. Start engine and allow it to idle. Waveforms should be as illustrated. (Scheme 73) If waveforms are not as illustrated, replace ECM and retest. If waveforms are as illustrated, go to next step. NOTE: Throttle control motor circuit waveform frequency will vary depending on throttle valve opening.
  3. Turn ignition off. Disconnect throttle control motor connector. Throttle control motor is located between accelerator cable and throttle body. Using an ohmmeter, measure resistance between throttle control motor connector terminals No. 1 (White wire) and No. 2 (Black wire). Resistance should be.3-100.0 ohms at 68°F (20°C). If resistance is not as specified, replace throttle control motor. If resistance is as specified, go to next step.
  4. Check for open or short circuit in wiring harness or connector between throttle control motor and ECM. See WIRING DIAGRAMS article. Repair wiring as necessary. If wiring and connectors are okay, replace ECM and retest.

Scheme 73

Scheme 73
Scheme 73
  1. Check ETCS fuse (15-amp) located in engine compartment fuse/relay box on driver's side wheel well. If ETCS fuse is okay, go to next step. If ETCS fuse is blown, check for short circuit in wiring harness between ETCS fuse and ECM. See WIRING DIAGRAMS article. Repair wiring as necessary.
  2. Backprobing connector, measure voltage between ground and terminal No. 7 (Yellow/Black wire) at ECM E3 connector. (Scheme 67) If voltage is 9-14 volts, replace ECM and retest. If voltage is not 9-14 volts, check circuits in wiring harness between battery, ETCS fuse and ECM. See WIRING DIAGRAMS article. Repair wiring as necessary.
  1. Disconnect throttle control motor connector. Throttle control motor is located between accelerator cable and throttle body. Using an ohmmeter, measure resistance between throttle control motor connector terminals No. 1 (White wire) and No. 2 (Black wire). Resistance should be .3-100.0 ohms at 68°F (20°C). If resistance is not as specified, replace throttle control motor. If resistance is as specified, go to next step.
  2. Visually inspect throttle valve for foreign material. Clean throttle valve as necessary. If throttle valve is clean, replace throttle body.

Retrieve trouble codes. See RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. If other codes are displayed, diagnose and repair those codes first and retest. If only DTC P1129 is displayed, replace ECM. Clear and retrieve trouble codes. If DTC P1129 is displayed again, replace throttle body and retest.

A 2-speed fuel pump is used to control fuel pressure. During engine cranking, ECM turns on control circuit of fuel pump relay in order to apply battery voltage to fuel pump and increase fuel pressure. Once engine starts, or while running under light load conditions, ECM opens fuel pump relay control circuit. Fuel pump voltage is then fed through fuel pump resistor, which lowers fuel pump voltage and reduces fuel pressure. Under heavy load conditions, ECM turns fuel pump relay back on to increase fuel pressure.

Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.

Note. This diagnostic procedure assumes that engine will start and run. If engine does not start, see DOES NOT START under SYMPTOMS in TROUBLE SHOOTING - NO CODES article.

  1. Access ECM at left front of engine compartment. Backprobing connector, measure voltage at ECM terminal No. 15 (Yellow wire) of ECM connector E3. When engine is idling or under light load, voltage should be 0-3 volts. When engine is cranking or under heavy load, voltage should be 9-14 volts. If voltage is as specified, replace ECM and retest system. If voltage is not as specified, go to next step.
  2. Check fuel pump relay operation. See RELAYS under MOTORS, RELAYS & SOLENOIDS in appropriate SYSTEM & COMPONENT TESTING article. Replace fuel pump relay as necessary. If fuel pump relay is okay, locate and repair open or short circuit in wiring or connectors between fuel pump relay and ECM connector E3. See WIRING DIAGRAMS article.
  1. Check for spark at misfiring cylinder. See IGNITION CHECKS in BASIC DIAGNOSTIC PROCEDURES article. If spark is present, go to next step. If spark is not present, go to step 4.
  2. Check for open or short in IGF and IGT circuits between ECM E2 or E4 connector and suspect coil/ignitor. See WIRING DIAGRAMS article. Repair as necessary. If circuits are okay, go to next step.
  3. Disconnect suspect ignition coil/ignitor connector. Turn ignition on. Backprobing connector, measure voltage between ground and appropriate ECM connector E4 terminal as follows: For cylinders No. 1 or 7, measure voltage at terminal No. 6 (Light Green wire). For cylinders No. 2 or 8, measure voltage at terminal No. 5 (Blue/Black wire). For cylinders No. 3 or 5, measure voltage at terminal No. 4 (Green/Black wire). For cylinders No. 4 or 6, measure voltage at terminal No. 7 (Green wire). (Scheme 67) If voltage is 4.5-5.5 volts, replace suspect ignition coil/ignitor. If voltage is not 4.5-5.5 volts, replace ECM and retest.
  4. Check for open or short in IGT circuit between suspect ignition coil/ignitor and appropriate ECM connector terminal. See «IGT CIRCUIT TERMINAL IDENTIFICATION»(ref-22522-S19500115492001010300000) table. Repair as necessary. If circuit is okay, go to next step. IGT CIRCUIT TERMINAL IDENTIFICATION Cylinder No. ECM Connector Terminal No. Wire Color 1 E5 17 Green/White 2 E4 13 Blue/Red 3 E5 16 Blue/Yellow 4 E4 12 Light Green 5 E5 27 Red 6 E4 11 Red/Blue 7 E5 26 Pink/Blue 8 E4 10 Black/White
  5. If using an oscilloscope, go to next step. If not using an oscilloscope, access ECM at left front of engine compartment. Backprobing connector, measure voltage between ground and each IGT circuit terminal at appropriate ECM connector while cranking engine. See «IGT CIRCUIT TERMINAL IDENTIFICATION»(ref-22522-S19500115492001010300000) table. If voltage is.1-4.5 volts, go to step 7. If voltage is not.1-4.5 volts, replace ECM and retest.
  6. Backprobing connector, connect oscilloscope between terminal No. 7 (Brown wire) of ECM E6 connector and each IGT circuit terminal at appropriate ECM connector. See «IGT CIRCUIT TERMINAL IDENTIFICATION»(ref-22522-S19500115492001010300000) table. Crank engine. Waveforms should be as illustrated. (Scheme 74) If waveforms are as illustrated, go to next step. If waveforms are not as illustrated, replace ECM and retest.
  7. Disconnect ignition coil connectors. Backprobing connector, measure voltage between ground and each IGT circuit terminal of appropriate ECM connector while cranking engine. See «IGT CIRCUIT TERMINAL IDENTIFICATION»(ref-22522-S19500115492001010300000) table. If voltage is.1-4.5 volts, go to next step. If voltage is not.1-4.5 volts, replace ECM and retest.
  8. Disconnect suspect ignition coil/ignitor connector. Measure voltage between ground and suspect coil/ignitor harness connector terminal No. 1 (Red wire). Turn ignition switch to ON position, then to START position. If voltage is not 9-14 volts, repair ignition coil/ignitor power source circuit. If voltage is 9-14 volts, go to next step.
  9. Check for open in White/Black wire between suspect ignition coil/ignitor connector terminal No. 4 and ground. See WIRING DIAGRAMS article. Repair as necessary. If circuit is okay, replace suspect ignition coil/ignitor.

Scheme 74

Scheme 74
Scheme 74
  1. Disconnect suspect VVT sensor connector. Measure resistance between VVT sensor harness connector terminals. Resistance should be 835-1400 ohms at 14-122°F (-10-50°C) or 1060-1645 ohms at 122-212°F (50-100°C). If using an oscilloscope, access ECM at left front of engine compartment. Backprobing connector, connect oscilloscope to following ECM terminals: For DTC P1345, connect between terminals No. 18 (Red wire) and No. 19 (Green wire) at ECM connector E5. For DTC P1350, connect between terminals No. 19 (Yellow wire) and No. 18 (Blue wire) at ECM connector E4. (Scheme 67) Start engine and allow to idle. Compare to specified oscilloscope pattern. (Scheme 75) If sensor resistance and/or oscilloscope pattern is as specified, go to next step. If sensor resistance or oscilloscope pattern is not as specified, replace VVT sensor.
  2. Check for open or short circuit in wire harness and connector between appropriate ECM connector and VVT sensor. Repair as necessary. If circuit is okay, inspect VVT sensor installation. Tighten sensor as necessary. If VVT sensor is installed properly, replace ECM and retest.

Scheme 75

Scheme 75
Scheme 75

Check valve timing. Check for damaged (missing teeth) timing belt. See appropriate article in ENGINES. Repair or adjust as necessary. If valve timing is okay, replace ECM and retest.

  1. Check valve timing. See appropriate article in ENGINES. Repair as necessary. If valve timing is okay, go to next step.
  2. Start and run engine. Allow engine to reach normal operating temperature. Connect Lexus scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Select VVT from scan tool ACTIVE TEST menu. Using scan tool, turn OCV on and off. If idle speed is normal with OCV off and engine idles rough or stalls when OCV is on, VVT 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. If idle speed does not function as specified, go to next step.
  3. Start engine. For left OCV, using oscilloscope, check waveform pattern between terminals No. 6 (Blue/Yellow wire) and No. 5 (Green/White wire) at ECM E5 connector. (Scheme 67) For right OCV, using oscilloscope, check waveform pattern between terminals No. 9 (Blue/White wire) and No. 8 (Blue/Black wire) at ECM E4 connector. On either application, slowly increase engine speed. Waveform frequency "A" should lengthen as engine speed increases. (Scheme 76) If readings are not as specified, replace ECM and retest. If readings are as specified, go to next step.
  4. Remove timing belt cover, timing belt and appropriate valve cover. See appropriate article in ENGINES. Remove suspect OCV from cylinder head. Place a shop towel under OCV cylinder head opening. Rotate appropriate VVT pulley from left to right about 25 degrees, 2-3 times. Oil should drain from OCV cylinder head opening. If oil does not drain from opening, replace suspect VVT pulley/gear assembly and go to next step. If oil drains from opening, go to next step.
  5. With suspect OCV removed, connect fused jumper wires between positive battery terminal and OCV connector terminal No. 1, and negative battery terminal and OCV connector terminal No. 2. (Scheme 77) OCV plunger should move away from connector. Remove fused jumper wires. OCV plunger should move back in direction of connector. If OCV plunger does not move as specified, replace suspect OCV and go to next step. If OCV plunger moves as specified, go to next step.
  6. Check for blockage in suspect OCV. Check oil check valve and oil passage located under suspect OCV. Repair as necessary. If components are okay, go to next step.
  7. Clear DTCs. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-22522-S27929095292001010300000) under SELF-DIAGNOSTIC SYSTEM. Duplicate driving conditions under which DTC P1349 or P1354 was set. Retrieve DTCs. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22522-S10006286822001010300000) under SELF-DIAGNOSTIC SYSTEM. If DTC P1349 or P1354 is set, replace ECM and retest. If DTC P1349 or P1354 is not set, VVT system 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.

Scheme 76

Scheme 76
Scheme 76

Scheme 77

Scheme 77
Scheme 77
  1. Check valve timing. See appropriate article in ENGINES. Repair as necessary. If valve timing is okay, go to next step.
  2. Start and run engine. Allow engine to reach normal operating temperature. Disconnect suspect OCV connector. Connect fused jumper wires between positive battery terminal and suspect OCV connector terminal No. 1, and negative battery terminal and OCV connector terminal No. 2. (Scheme 77) If engine speed does not change with OCV disconnected and changes (rough idle or stalls) with fused jumper wires connected, go to next step. If results are not as specified, go to step 4.
  3. Start engine. Backprobe ECM connector. For left OCV, using oscilloscope, check waveform pattern between terminals No. 6 (Blue/Yellow wire) and No. 5 (Green/White wire) at ECM E5 connector. (Scheme 67) For right OCV, using oscilloscope, check waveform pattern between terminals No. 9 (Blue/White wire) and No. 8 (Blue/Black wire) at ECM E4 connector. Slowly increase engine speed. Waveform frequency "A" should lengthen as engine speed increases. (Scheme 76) If readings are not as specified, replace ECM and retest. If readings are as specified, go to next step.
  4. Remove timing belt cover, timing belt and appropriate valve cover. See appropriate article in ENGINES. Remove suspect OCV from cylinder head. Place a shop towel under OCV cylinder head opening. Rotate appropriate VVT pulley from left to right about 30 degrees, 2-3 times. Oil should drain from OCV cylinder head opening. If oil does not drain from opening, replace suspect VVT pulley/gear assembly and go to next step. If oil drains from head openings, go to next step.
  5. With suspect OCV removed, connect fused jumper wires between positive battery terminal and OCV connector terminal No. 1, and negative battery terminal and OCV connector terminal No. 2. (Scheme 77) OCV plunger should move away from connector. Remove fused jumper wires. OCV plunger should move back in direction of connector. If OCV plunger does not move as specified, replace suspect OCV and go to next step. If OCV plunger moves as specified, go to next step.
  6. Check for blockage in suspect OCV. Check oil check valve and oil passage located under suspect OCV. Repair an necessary. If components are okay, go to next step.
  7. Clear DTCs. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-22522-S27929095292001010300000) under SELF-DIAGNOSTIC SYSTEM. Duplicate driving conditions under which DTC P1349 or P1354 was set. Retrieve DTCs. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22522-S10006286822001010300000) under SELF-DIAGNOSTIC SYSTEM. If DTC P1349 or P1354 is set, replace ECM and retest. If DTC P1349 or P1354 is not set, VVT system is okay 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.
  1. Check stoplights. If stoplights do not function properly, repair as necessary and retest system. See EXTERIOR LIGHTS article in ACCESSORIES & EQUIPMENT. If stoplights function properly, go to next step.
  2. If using Lexus scan tool, go to next step. If not using Lexus scan tool, go to step 4.
  3. Connect Lexus scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Turn ignition on. Using scan tool, read STP signal while depressing and releasing brake pedal. STP signal should be on when brake pedal is depressed. STP signal should be off when brake pedal is released. If STP signal does not operate as specified, go to step 5. If STP signal operates as specified, check wire harness and connectors. Problem is intermittent.
  4. Access ECM at left front of engine compartment. Turn ignition on. Backprobing connector, measure voltage between ground and terminal No. 4 (Green/Orange wire) at ECM E2 connector. (Scheme 67) With brake pedal depressed, voltage should be 7.5-14.0 volts. With brake pedal released, voltage should be less than 1.5 volts. If voltage is not as specified, go to next step. If voltage is as specified, check wire harness and connectors. Problem is intermittent.
  5. Check for short circuit in wiring harness between ECM and stoplight switch. See WIRING DIAGRAMS article. Repair as necessary and retest system. If wiring harness is okay, replace ECM. Retest system.
  1. Backprobing connector, measure voltage between ground and terminal No. 4 (Black/Red wire) at ECM E3 connector. (Scheme 67) If voltage is not 9-14 volts, go to next step. If voltage is 9-14 volts, replace ECM and retest.
  2. Remove and inspect EFI NO.1 fuse (30-amp) from fuse/relay block located in front of driver's side wheel well. If fuse is blown, check cause of blown fuse and repair as necessary. If fuse is okay, check and repair wiring harness or connector between battery, EFI fuse and ECM. See WIRING DIAGRAMS article.

Replace ECM.

See appropriate MULTIPLEX CONTROL SYSTEMS article in ACCESSORIES & EQUIPMENT.

Note. If using Lexus scan tool, go to step 1 . If not using Lexus scan tool, go to step 2 .

  1. Start and run engine. Allow engine to reach normal operating temperature. Connect Lexus scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Select VVT from scan tool ACTIVE TEST menu. Using scan tool, turn OCV on and off. If idle speed is normal with OCV off and engine idles rough or stalls when OCV is on, VVT is functioning properly at this time. Fault is intermittent. 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. If idle speed does not function as specified, go to next step.
  2. With engine running. Disconnect suspect OCV electrical connector. Connect fused jumper wires between positive battery terminal and OCV connector terminal No. 1, and negative battery terminal and OCV connector terminal No. 2. (Scheme 77) Engine should idle rough or stall. If OCV operates as specified, go to next step. If OCV does not operate as specified, replace OCV.
  3. Start engine. Backprobe ECM connector. For left OCV, using oscilloscope, check waveform pattern between terminals No. 6 (Blue/Yellow wire) and No. 5 (Green/White wire) at ECM E5 connector. (Scheme 67) For right OCV, using oscilloscope, check waveform pattern between terminals No. 9 (Blue/White wire) and No. 8 (Blue/Black wire) at ECM E4 connector. Slowly increase engine speed. Waveform frequency "A" should lengthen as engine speed increases. (Scheme 76) If readings are not as specified, replace ECM and retest. If readings are as specified, go to next step.
  4. Check for an open or short circuit in wire harness and connector between suspect OCV and ECM E5 or ECM E4 connector. Repair as necessary. If circuit and connector are okay, problem is intermittent.
  1. If using OBD-II scan tool, go to next step. If using Lexus scan tool, connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Turn ignition on. Turn scan tool on. Move shift lever through all gear positions one at a time. Read PNP, REVERSE, DRIVE, "4", "3", "2" and LOW signals on scan tool. If all signals switch from OFF to ON, replace ECM and retest. If all signals do not switch from OFF to ON, go to step 3.
  2. Access ECM at left front of engine compartment. Turn ignition on. Move shift lever through all gear positions one at a time. Backprobing connector, check for battery voltage between ground and appropriate ECM connector terminal at each gear position. (Scheme 67) See «IDENTIFYING ECM CONNECTORS & TERMINALS»(ref-22522-S39797216282001010300000) table. If battery voltage exists as specified, replace ECM and retest. If battery voltage does not exist as specified, go to next step. IDENTIFYING ECM CONNECTORS & TERMINALS Gear Position ECM Connector Terminal No. (Wire Color) Park E6 6 (White) Reverse (1) E6 5 (Green) Neutral E6 3 (Green/Red) Drive E2 13 (Green/Yellow) 4 E2 14 (Blue/Yellow) 3 E6 4 (Blue/Yellow) 2 E2 12 (Green/Black) Low E2 15 (Yellow/Black) (1) Voltage should be less due to back-up light illuminating.
  3. Raise and support vehicle. Disconnect PNP switch Gray 9-pin connector. Move shift lever through all gear positions one at a time. Check for continuity between appropriate terminals at PNP switch Gray 9-pin connector at each gear position. (Scheme 78) See «IDENTIFYING PARK/NEUTRAL POSITION SWITCH TERMINALS»(ref-22522-S09959712172001010300000) table. If continuity does not exist as specified, replace PNP switch and retest. If continuity exists as specified, check for short or open circuit in wire harness and connector between battery and PNP switch, and PNP switch and ECM. See WIRING DIAGRAMS article. Repair as necessary.
Gear PositionTerminals No.
Park1-3 & 6-9
Reverse2-3
Neutral3-5 & 6-9
Drive3-7
23-4
Low3-8

IDENTIFYING PARK/NEUTRAL SWITCH TERMINALS

Scheme 78

Scheme 78
Scheme 78

More articles — Engine Controls - Self-Diagnostics - LS430