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Engine Controls - Tests W/codes: Diagnosis Lexus GS II

Testing & Diagnostics 13 illustrations ~12667 words

MALFUNCTION INDICATOR LIGHT (MIL) INSPECTION

Note. The 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 appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. See «ECM LOCATION»(ref-22508-S41587861882001010300000) .
  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-22508-S22034545892001010300000) .

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 Connect appropriate OBD-II scan tool. Retrieve codes and record any freeze-frame data. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22508-S22034545892001010300000) .
  3. Clear Trouble Codes Clear codes using scan tool. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-22508-S03887009072001010300000) .
  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 TROUBLE CODE (DTC) IDENTIFICATION»(ref-22508-S07549260072001010300000) . If no codes are present, proceed to «TESTS W/O CODES»(ref-22513) article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.).
  7. Verification Procedure After repairs have been completed, clear all diagnostic trouble codes. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-22508-S03887009072001010300000) . Perform road test. Ensure no codes are present and all symptoms and/or complaints have been repaired.

RETRIEVING DIAGNOSTIC TROUBLE CODES

Note. 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. Only Lexus scan tool 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 in which DTC was set. CHECK mode contains a higher sensing ability to detect malfunctions. CHECK mode helps determine malfunctions caused by poor electrical connections, which are difficult to determine using NORMAL mode.

Note. If using Lexus scan tool, when ignition is turned from ON to ACC or OFF position or 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.

Scheme 5

Scheme 5: NORMAL Mode Code Retrieval
Scheme 5: NORMAL Mode Code Retrieval
  1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) DLC No. 3 is located under left side of instrument panel. Turn ignition on with engine off. Turn scan tool on. Using scan tool manufacturer's instructions, check for DTCs and freeze-frame data.
  2. If scan tool displays UNABLE TO CONNECT TO VEHICLE, DLC No. 3 must be checked. See «DLC NO. 3 INSPECTION»(ref-22508-S24102684462001010300000) under SCAN TOOL PROBLEMS. If scan tool does not display UNABLE TO CONNECT TO VEHICLE, go to next step.
  3. Record any DTCs and freeze-frame data displayed for system diagnosis. If driveability problem exists and no DTCs are present, go to «TESTS W/O CODES»(ref-22513) article for diagnosis by symptom.
  4. If any DTCs are present, perform appropriate circuit test. See «DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION»(ref-22508-S07549260072001010300000). For more information on freeze-frame data, see «FREEZE-FRAME DATA»(ref-22508-S31853449672001010300000) under INTRODUCTION. For information on 2-trip detection logic codes, see «DETECTION LOGIC»(ref-22508-S38619850832001010300000) under INTRODUCTION.
  5. After repairs for DTC have been completed, DTCs must be cleared from ECM memory. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-22508-S03887009072001010300000).

CHECK Mode Code Retrieval (Lexus Scan Tool Only)

  1. Ensure vehicle battery is fully charged (at least 11 volts). Apply parking brake. 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. (Scheme 5) 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 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 «TESTS W/O CODES»(ref-22513) article for diagnosis by symptom.
  5. If any DTCs are present, perform appropriate circuit test. See «DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION»(ref-22508-S07549260072001010300000). For more information on freeze-frame data, see «FREEZE-FRAME DATA»(ref-22508-S31853449672001010300000) under INTRODUCTION. For information on 2-trip detection logic codes, see «DETECTION LOGIC»(ref-22508-S38619850832001010300000) under INTRODUCTION.
  6. After repairs for DTC have been completed, DTC must be cleared from ECM memory. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-22508-S03887009072001010300000).

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 by using scan tool and 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 from junction block 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.

TEST PREPARATION

  1. Manufacturer recommends using Check Harness "A" (SST 09990-01000) when using circuit tests to diagnose malfunctions. Check harness "A" is a test harness that is installed between Electronic Control Module (ECM) and ECM connectors. (Scheme 6) Voltage and resistance readings are taken at check harness connectors. NOTE: Always check and note diagnostic trouble codes prior to disconnecting ECM connector. Disconnecting ECM connector will erase codes from memory.
  2. To install check harness "A", ensure ignition switch is in the OFF position. Disconnect ECM connector. ECM is located behind glove box.
  3. Connect check harness "A" between ECM and ECM connector. Terminal arrangement of check connector is the same as those on the ECM. Wire colors that are specified in procedures apply to ECM connectors, but may not apply to check harness connectors. Proceed to appropriate circuit test.

Scheme 6

Scheme 6
Scheme 6

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. The test drive confirmation test will duplicate the 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 with proper DTC circuit test.

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 appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) 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-22508-S28545331412001010300000) table. (Scheme 7) If voltage and resistance readings are not as specified, check wiring circuit. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article.

Note. Terminal No. 2 on DLC No. 3 provides the pulse generation during the information transmission from the Engine Control Module (ECM).

Pin No. (Application)Specification
4 (Chassis Ground)One Ohm or Less
5 (Signal)One Ohm or Less
16 (Battery Voltage)9-14 Volts

DLC NO. 3 VOLTAGE & RESISTANCE SPECIFICATIONS

Scheme 7

Scheme 7
Scheme 7

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 SYSTEM/COMPONENT TESTS article.

Note. For for identification of circuits, terminals and wire colors referenced in the following testing, see appropriate wiring diagram in SYSTEM WIRING DIAGRAMS article.

CAUTIONIf ECM replacement is instructed in following testing, always ensure ECM harness connector and ground circuit are okay. If either are suspect, repair as necessary and repeat testing to confirm ECM malfunction.

Circuit Description

MAF sensor uses a platinum hot wire maintained at a constant temperature. Airflow past sensor affects temperature and current flow through sensor. If DTC P0100 is set, ECM will operate in fail-safe mode (ignition timing fixed at 5 degrees BTDC). DTC P0100 is set when ECM detects a open or short circuit for 3 seconds, with engine speed around 4000 RPM. Possible causes are

  1. MAF circuit open or shorted.
  2. MAF sensor.
  3. ECM.

Diagnosis & Repair

  1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) Turn ignition on. Turn scan tool 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 once engine is at normal operating temperature, go to step 5).
  2. Disconnect MAF sensor connector. Turn ignition on. Using DVOM, measure voltage between ground and terminal No. 4 (Black/Red 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 Black/Red wire between MAF sensor connector and EFI main relay. EFI main relay is located in engine compartment junction block, at right side of engine compartment.
  3. Access ECM at left front of engine compartment. Start engine. Backprobing, measure voltage between ground and terminal No. 10 (Red/Blue wire) at ECM E3 connector. (Scheme 8) If voltage is 1.1-1.5 volts, replace ECM and retest.
  4. If voltage is not 1.1-1.5 volts, check for an open or short in Red/Blue wire between MAF sensor and ECM E3 connector. If wiring is okay, replace MAF sensor and retest.
  5. Access ECM at left front of engine compartment. Turn ignition off. Backprobing, check for continuity between ground and terminal No. 19 (Gray wire) at ECM E3 connector. If continuity does not exist, replace ECM and retest. If continuity exists, go to next step.
  6. Check for open in Gray wire between MAF sensor and ECM E3 connector. Repair as necessary. If wire is okay, replace MAF sensor.

Scheme 8

Scheme 8
Scheme 8

MAF sensor uses a platinum hot wire maintained at a constant temperature. Airflow past sensor affects temperature and current flow through sensor. ECM will operate in fail-safe mode if DTC P0101 is set. DTC P0101 is set when throttle valve is fully closed, MAF sensor output is more than 2.2 volts, and engine is at operating temperature for 10 seconds or more at engine speed of 900 RPM or less.

DTC P0101 will also set when Throttle Position (TP) sensor output is .63 volt or more, and MAF sensor output is less than 1.0 volt for 6 seconds or more at engine speed of 1500 or more. Possible cause is

  1. MAF sensor.

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. (Scheme 5) 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.
  2. If temperature displayed is 284°F (140°C) or more, go to step 5). If temperature displayed is -40°F (-40°C), turn ignition off. Disconnect MAF sensor connector. Connect a fuse jumper wire between terminals No. 1 (White/Red wire) and No. 2 (Brown wire) at MAF sensor harness connector. Turn ignition on. Using scan tool, monitor IAT sensor temperature.
  3. 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), turn ignition off. Remove fuse jumper wire. Access ECM at left front of engine compartment. Backprobing, connect fuse jumper wire between terminals No. 22 (White/Red) wire and No. 18 (Brown wire) at ECM E3 connector. (Scheme 8)
  4. If temperature displayed on scan tool is 284°F (140°C) or more, check and repair White/Red wire and Brown wire between MAF sensor harness connector and ECM E3 connector. If temperature displayed on scan tool is not 284°F (140°C) or more, replace ECM and retest.
  5. 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.
  6. Access ECM at left front of engine compartment. Disconnect E3 connector from ECM. Turn ignition on. If the temperature displayed is -40°F (-40°C), locate and repair short in White/Red wire and Brown wire between MAF sensor and ECM E3 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. (Scheme 5) 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.
  2. If temperature displayed is 284°F (140°C), go to step 5). If temperature displayed is -40°F (-40°C), 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.
  3. 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, turn ignition off. Remove fused jumper wire. Access ECM at left front of engine compartment. Backprobing, connect fuse jumper wire between terminals No. 14 (Black/Red) and No. 18 (Brown wire) at ECM E3 connector. (Scheme 8)
  4. If temperature displayed on scan tool is 284°F (140°C) or more, check for an open in Red/Black wire and Brown wire between ECT harness connector and ECM E3 connector. If temperature displayed on scan tool is not 284°F (140°C) or more, replace ECM and retest.
  5. 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.
  6. Access ECM at left front of engine compartment. Disconnect E3 connector from ECM. Turn ignition on. If the temperature displayed is -40°F (-40°C), check for short in Red/Black wire and Brown wire between ECT sensor and ECM E3 connector. If temperature displayed by scan tool is not -40°F (-40°C), replace ECM and retest.

The ECT sensor is a thermistor that monitors coolant temperature. DTC P0116 is set when after engine has been running for 20 minutes ECM detects a temperature of less than 20.5°F (-6.4°C) on THW or THA circuit, and actual engine coolant temperature is 68°F (20°C) or less. DTC P0116 is also set when after engine has been running for 5 minutes ECM detects a temperature of 20.5°F (-6.4°C) or more, and less than 50°F (10°C) on THW or THA, and actual engine coolant temperature is 68°F (20°C) or less. DTC P0116 is also set when after engine has been running for 2 minutes ECM detects a temperature of 50°F (10°C) or more on THW or THA circuit, and actual engine coolant temperature is 68°F (20°C) or less. Possible causes are

  1. ECT sensor.
  2. Engine cooling system.

Note. If DTCs P0115 and P0116 are output together, inspect ECT circuits for an open. Repair as necessary. See appropriate wiring diagram in SYSTEM WIRING DIAGRAMS article. Repair DTC P0115 fist.

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. 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. (Scheme 5) Turn ignition on. Turn scan tool on. Using Lexus scan tool, monitor throttle valve opening percentage at VTA circuit and voltage at VTA2 circuit. Opening percentage should be 64-96 and voltage should be 4.6-5.1 volts with a fully closed throttle. Depress accelerator pedal to floor (WOT). Opening percentage should be 8-20 and voltage should be 2-2.9 volts with a fully open 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, measure voltage between ECM E3 connector terminals No. 2 (Blue/Yellow wire) and No. 18 (Brown wire). (Scheme 8) 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, measure voltage between ECM E3 connector terminals No. 23 (Yellow/Green wire), No. 24 (Yellow/Red wire) and No. 18 (Brown wire). With fully closed throttle, VTA circuit voltage should be.4-1 volt and VTA2 circuit voltage should be 2-2.9 volts. With fully open throttle, VTA circuit voltage should be 3.2-4.8 volts and VTA2 circuit voltage should be 4.6-5.1 volts. 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 «SYSTEM/COMPONENT TESTS»(ref-22514) 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 E3 connector and TP sensor.

Diagnosis & Repair (Using OBD-II Scan Tool)

  1. Access ECM at left front of engine compartment. Turn ignition on. Backprobing, measure voltage between ECM E3 connector terminals No. 2 (Blue/Yellow wire) and No. 18 (Brown wire). (Scheme 8) 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, measure voltage between ECM E3 connector terminals No. 23 (Yellow/Green wire), No. 24 (Yellow/Red wire) and No. 18 (Brown wire). With fully closed throttle, VTA circuit voltage should be.4-1 volt and VTA2 circuit voltage should be 2-2.9 volts. With fully open throttle, VTA circuit voltage should be 3.2-4.8 volts and VTA2 circuit voltage should be 4.6-5.1 volts. 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 «SYSTEM/COMPONENT TESTS»(ref-22514) 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 E3 connector and TP sensor. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair as necessary.

The TP sensor is a 2 variable resistor sensor that monitors throttle opening and TP sensor malfunction. Based on the TP sensor signal, the ECM determines vehicle driving condition and adjusts air/fuel mixture accordingly. DTC is set when VTA and VTA2 circuit voltage on TP sensor is out of range for 2 seconds. Possible cause is

  1. TP sensor.
  2. ECM.

Replace TP sensor and retest.

  1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) 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.
  2. If a rich signal is indicated for both sensors, replace ECM and retest. If either sensor does not display a rich signal, check for open or short circuit in wiring harness between ECM and suspect sensor. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair as necessary. If wiring harness is okay, check for misfire. See «DTCS P0300-P0306»(ref-22508-S36284227792001010300000) RANDOM MISFIRE DETECTED. If misfire is not detected, check for exhaust leaks. If exhaust leaks are not detected, replace oxygen sensor and retest.

Confirmation Test

  1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) If using OBD-II scan tool, go to next step. If using Lexus scan tool, switch to CHECK mode. Ensure all accessories are off. Start and warm engine to normal operating temperature. Drive vehicle at 31-40 MPH for 1-3 minutes. Stop vehicle and allow to idle for one minute. Repeat driving and idle part of test 3 more times. If malfunction exists, MIL will illuminate.
  2. If using OBD-II scan tool, ensure all accessories are off. Start and warm engine to normal operating temperature. Drive vehicle at 31-40 MPH for 1-3 minutes. Stop vehicle and allow to idle for one minute. Turn engine off. Repeat driving and idle part of test. If malfunction exists, MIL will illuminate.
  1. Check for open or short circuit in connector or in wiring harness between ECM and oxygen sensor. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair as necessary. If wiring harness is okay, connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 5)
  2. Start engine and warm to normal operating temperature. Using scan tool, monitor heated oxygen sensor output voltage and short-term fuel trim. If scan tool indicates a lean condition (voltage fluctuates around.55 volt or less, and short term fuel trim fluctuates around +20 trim) or rich condition (voltage fluctuates around.35 volt or more, and short term fuel trim fluctuates around -20 trim), see «DTC P0171 OR P0172»(ref-22508-S31731500132001010300000) FUEL TRIM circuit test.
  3. If scan tool indicates specifications are other than in step 2), operate engine at 2500 RPM for 90 seconds. Using scan tool, monitor oxygen sensor voltage. If voltage constantly fluctuates between.35-.55 volt, repeat CONFIRMATION TEST. If voltage does not fluctuate between.35-.55 volt, replace oxygen sensor and retest.

Retrieve trouble codes. See RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. If only DTC P0133 or P0153 is displayed, replace appropriate oxygen sensor and retest. If other codes are displayed, diagnose and repair those codes first and retest.

  1. Access ECM at left front of engine compartment. Turn ignition on. If DTC P0135 is set, backprobing, measure voltage between ground and terminal No. 4 (Red wire) at ECM E3 connector. (Scheme 8) If DTC P0141 is set, backprobing, measure voltage between ground and terminal No. 26 (Gray wire) at ECM E7 connector. If DTC P0155 is set, backprobing, measure voltage between ground and terminal No. 3 (Yellow wire) at ECM E3 connector. If DTC P0161 is set, backprobing, measure voltage between ground and terminal No. 25 (Gray/Black wire) at ECM E7 connector.
  2. If voltage is 9-14 volts at any circuit, replace ECM and retest. If voltage is not 9-14 volts at any circuit, turn ignition off. Disconnect appropriate oxygen sensor harness connector. Using ohmmeter, measure resistance between terminals No. 1 and 2 at oxygen sensor connector. See «IDENTIFYING OXYGEN SENSOR HEATER TERMINALS»(ref-22508-S17154145342001010300000) table. IDENTIFYING OXYGEN SENSOR HEATER TERMINALS Application Pin No. 1 Wire Color Pin No. 2 Wire Color Bank 1, Sensor 1 Red Wire Black/Red Wire Bank 1, Sensor 2 Gray Wire Black/Red Wire Bank 2, Sensor 1 Yellow Wire Black/Red Wire Bank 2, Sensor 2 Gray/Black Wire Black/Red Wire
  3. With sensor temperature at 68°F (20°C), resistance should be 11-16 ohms. If resistance is as specified, check wiring harness between EFI main relay, oxygen sensor and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair as necessary. If resistance is not as specified, replace appropriate sensor and retest.
  1. Retrieve trouble codes. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22508-S22034545892001010300000) 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 and P0156 are displayed, check for open or short circuit in wiring harness between ECM and suspect oxygen sensor. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair wiring as necessary.
  2. If wiring harness is okay, connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) 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. Raise engine speed to 4000 RPM for 3 minutes. Voltage should fluctuate from.4 volt or less to.5 volt or more.
  3. 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. Check with vehicle owner if vehicle has run out of fuel. If vehicle has run out of fuel, clear DTCs and retest for DTC PO171. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-22508-S03887009072001010300000) under SELF-DIAGNOSTIC SYSTEM and «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22508-S22034545892001010300000) under SELF-DIAGNOSTIC SYSTEM. If vehicle has not run out of fuel, go to next step.
  2. Check all air induction components. Repair as necessary. If air induction components are okay, connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) Start engine and warm to normal operating temperature. Monitor bank No. 1 and No. 2 heated oxygen sensor No. 1 output voltage and short-term fuel trim.
  3. If scan tool indicates a lean condition (voltage fluctuates around.55 volt or less, short-term will fluctuate around +20 trim) or rich condition (voltage fluctuates around.35 volt or more, and short-term will fluctuate around -20 trim), go to next step. If results are other than specified, see «DTC P0130 OR P0150»(ref-22508-S02626575712001010300000) HEATED OXYGEN SENSOR circuit test.
  4. Check fuel pressure. See «BASIC TESTING»(ref-22506) article. Repair as necessary. If fuel pressure is okay, check fuel injectors. See «SYSTEM/COMPONENT TESTS»(ref-22514) article. Replace injectors as necessary.
  5. If all injectors are okay, check MAF and ECT sensors. See «SYSTEM/COMPONENT TESTS»(ref-22514) article. If MAF and ECT sensors are okay, check primary and secondary ignition systems for proper operation. Repair as necessary. If primary and secondary ignition systems are okay, go to next step.
  6. Check for exhaust system leakage. Repair as necessary. If exhaust system is okay, replace ECM and retest.

A misfire is determined by the ECM. The ECM uses signals provided by the crankshaft and camshaft position sensors. If the engine speed rate has changed enough to equal a preset number, a misfire is detected and the MIL is illuminated. If the misfire rate is high enough, and driving conditions will cause catalytic converter damage or overheating, the MIL blinks when a misfire is occurring.

DTC P0300 is set when misfiring of random cylinders is detected during any particular 200 or 1000 revolutions of engine. DTC P0301-306 are set when any particular 200 revolutions of engine, misfiring is detected which can cause catalytic converter overheating and/or damage.

DTC P0301-306 are also set when any particular 1000 revolutions of engine, misfiring is detected which can cause a deterioration in emission levels. Possible causes are

  1. Ignition system.
  2. Injector(s).
  3. Fuel pressure.
  4. Engine compression.
  5. Valve clearance.
  6. Valve timing.
  7. Mass Airflow (MAF) sensor.
  8. Engine Coolant Temperature (ECT) sensor.
  9. Open or short in engine wiring.
  10. Pure connector connection.
  11. ECM.
  1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) Check for any DTCs and freeze frame data. If any other DTCs are set diagnose them first. If using Lexus scan tool, switch to CHECK mode. Drive vehicle several times within freeze frame data parameters. If using OBD-II scan tool, turn engine off after driving vehicle.
  2. If freeze frame data is not available, start engine and allow to idle for 3.5 minutes or more. Increase engine speed to 1000 RPM for 3 minutes or more. Increase engine speed to 2000 RPM for 1.5 minutes or more. Increase engine speed to 3000 RPM for 1 minute or more. Check for any DTCs and freeze frame data. Turn ignition off for 5 seconds.

Note. If any other DTCs are output, repair those DTCs first.

  1. Check for misfire during engine warm up only. Check for use of improper fuel. Check proper connector connections. Also check for proper vacuum hose connection. Repair as necessary. If connector connections and vacuum hoses are okay, go to next step.
  2. Check spark plugs and check for spark. See «BASIC TESTING»(ref-22506) article. Repair as necessary. If spark plugs are okay and spark exists, go to next step.
  3. Access ECM at left front of engine compartment. Turn ignition on. Backprobing, measure voltage between ground and injector terminals at ECM E3 or E2 connector. (Scheme 8) See «IDENTIFYING INJECTOR TERMINALS»(ref-22508-S31195825112001010300000) table. If voltage is 9-14 volts for each circuit, go to step 5). If voltage is not 9-14 volts, go to next step. IDENTIFYING INJECTOR TERMINALS Injector Terminal No. Wire Color 1 5 (1) Yellow 2 6 (1) Black/White 3 1 (2) Blue 4 2 (2) Red 5 3 (2) White 6 4 (2) Red/Blue (1) Terminals are located in ECM E3 connector. (Scheme 8) (2) Terminals are located in ECM E2 connector. (Scheme 8)
  4. Disconnect injector of misfiring cylinder. Using ohmmeter, measure resistance between injector terminals. With injector temperature at 68°F (20°C), resistance should be 13.4-14.2 ohms. If resistance is as specified, check for open or short circuit in wiring harness between ECM E3 or E2 connector and injector. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair as necessary. If resistance is not as specified, replace suspect injector.
  5. Check fuel pressure. See «BASIC TESTING»(ref-22506) article. Repair as necessary. If fuel pressure is okay, check fuel injectors. See «SYSTEM/COMPONENT TESTS»(ref-22514) article. Replace as necessary.
  6. If all injectors are okay, check MAF sensor or ECT sensor. See «SYSTEM/COMPONENT TESTS»(ref-22514) article. Replace as necessary. If MAF sensor and ECT sensor are okay, check engine compression, valve clearance and valve timing. See «BASIC TESTING»(ref-22506) article. Repair as necessary.
  1. Access ECM at left front of engine compartment. Disconnect ECM E2 connector. Measure resistance between ground and terminals No. 28 (Black wire) and No. 27 (Gray wire) at ECM E2 harness connector. (Scheme 8) If both readings are infinite, go to step 3). If any reading is not infinite, go to next step.
  2. Disconnect suspect knock sensor connector. Using an ohmmeter, check for continuity between suspect knock sensor terminal and knock sensor body. If continuity exists, replace sensor. If continuity does not exist, go to next step.
  3. Check for an open or short in Black wire or Gray wire between knock sensor and ECM E2 connector. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair as necessary. If wiring is okay, go to next step.
  4. Substitute knock sensor with a known-good sensor and retest. If malfunction is corrected, replace knock sensor. If malfunction is still present, replace ECM and retest.
  1. Access ECM at left front of engine compartment. Disconnect ECM E2 connector. (Scheme 8) Using ohmmeter, measure resistance between ECM E2 harness connector terminals No. 23 (White wire) and No. 22 (Blue wire). (Scheme 8) Measured resistance should be 1630-2740 ohms with the engine temperature at 14-122°F (-10-50°C), or 2065-3225 ohms with engine temperature at 122-212°F (50-100°C).
  2. If resistance is not as specified, check for short or open circuits in wire harness between ECM E2 connector and CKP. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair as necessary. If circuits are okay, replace CKP sensor. If resistance is as specified, go to next step.
  3. Check CKP sensor and signal plate for proper installation and looseness. Ensure CKP sensor and signal plate are not loose. Replace as necessary. If CKP sensor and signal plate are okay, replace ECM and retest.
  1. Access ECM at left front of engine compartment. Disconnect ECM E2 connector. (Scheme 8) Using ohmmeter, measure resistance between ECM E2 connector terminals No. 10 (Yellow wire) and No. 22 (Blue wire). (Scheme 8) 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).
  2. If resistance is not as specified, check for open or short circuits in wire harness between ECM E2 connector and CMP. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair as necessary. If wiring harness is okay, replace CMP sensor. If resistance is as specified, go to next step.
  3. Check CMP sensor for proper installation and loosens. If CMP sensor is okay, replace ECM and retest.

Connect Lexus scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) Ensure all accessories are turned off. Start and warm engine to normal operating temperature. Increase engine speed to 2500-3000 RPM for 3 minutes. Using Lexus scan tool, ensure heated oxygen sensors (bank 1 and 2 sensor 1 and 2) feedback to ECM fluctuates around.5 volts.

  1. Retrieve trouble codes. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22508-S22034545892001010300000) 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 P0150»(ref-22508-S02626575712001010300000) HEATED OXYGEN SENSOR circuit 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»(ref-22508-S40644240802001010300000) HEATED OXYGEN SENSOR circuit 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 to set. If fuel tank cap was not loose, check for cracks, deformations or loose connections in the 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 vapor pressure sensor VSV, and between vapor pressure sensor 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, measure voltage between terminals No. 2 (Blue/Yellow wire) and No. 18 (Brown wire) at ECM E3 connector. (Scheme 8) 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.
  10. Backprobing ECM harness connector, measure voltage between terminals No. 18 (Blue/Yellow wire) at ECM E5 connector and No. 18 (Brown wire) at ECM E3 connector. Disconnect vacuum hose from vapor pressure sensor. Sensor is located next 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 1.2-19.7 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 in wiring harness between vapor pressure sensor and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair as necessary. If wiring is okay, replace vapor pressure sensor.
  12. Disconnect fuel tank-to-charcoal canister vacuum hose from charcoal canister. Ensure fuel tank cap is installed properly. Using compressed air, apply.71 psi (.05 kg/cm 2 ) to fuel tank. If tank does not hold pressure for a minimum of one minute, replace fuel tank. If tank holds pressure, no fault is indicated at this time. Probable cause of DTC P0440 to set was an incorrectly installed fuel tank cap.
  1. Check for loose or disconnected connectors at EVAP VSV, vapor pressure sensor VSV and vapor pressure sensor. Repair as necessary. If all connectors are okay, go to next step.
  2. Check for correct routing, damage, looseness and blockage in vacuum hoses between vapor pressure sensor and vapor pressure sensor VSV, and between vapor pressure sensor VSV and charcoal canister. Also check vacuum hoses between EVAP VSV and charcoal canister, between EVAP VSV and air resonator, and between intake manifold and charcoal canister. Repair as necessary. If vacuum hoses are okay, go to next step.
  3. Access ECM at left front of engine compartment. Turn ignition on. Backprobing, measure voltage between terminals No. 2 (Blue/Yellow wire) and No. 18 (Brown wire) at ECM E3 connector. (Scheme 8) 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.
  4. Backprobing, measure voltage between terminals No. 18 (Blue/Yellow wire) at ECM E5 connector and No. 18 (Brown wire) at ECM E3 connector. (Scheme 8) Disconnect vacuum hose from vapor pressure sensor. Sensor is located next 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 1.2-19.7 in. Hg applied, go to step 6). If voltage is not as specified, go to next step.
  5. Check for an open or short circuit in wiring harness and connector between vapor pressure sensor and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair as necessary. If wiring harness and connector are okay, replace vapor pressure sensor and retest.
  6. Connect Lexus scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) Using scan tool, select ACTIVE TEST mode. Disconnect EVAP VSV vacuum hose from charcoal canister. Start and run engine.
  7. Connect vacuum gauge to disconnect EVAP VSV vacuum hose. Check for vacuum at vacuum hose when EVAP VSV is activated by scan tool. Vacuum should exist with EVAP VSV switched on. Vacuum should not exist with EVAP VSV switched off. If EVAP VSV operates as specified, go to step 12). If EVAP VSV does not operate as specified, go to next step.
  8. 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.
  9. Remove EVAP VSV. Using ohmmeter, measure resistance between VSV terminals. With VSV temperature at 68°F (20°C), resistance should be 33-39 ohms. Measure resistance between each terminal and body of valve. Resistance should be infinite. If resistance is as specified, go to next step. If resistance is not as specified, replace EVAP VSV and charcoal canister. After replacing components clean vacuum hoses between throttle body and EVAP VSV, and between EVAP VSV and charcoal canister.
  10. 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 9) Disconnect fused jumper wires. Air should not flow from port "F". If EVAP VSV does not operate 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.
  11. Check for open or short circuit in wiring harness and connector between EFI main relay, EVAP VSV and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair as necessary. If wiring harness is okay, replace ECM and retest.
  12. Turn ignition on. Turn Lexus scan tool on. Using scan tool, select ACTIVE TEST mode. Using scan tool turn vapor pressure sensor VSV on. Apply air pressure to VSV port "E". Air should flow from port "F". (Scheme 10) Using scan tool turn vapor pressure sensor VSV off. Air should flow from port "G". If vapor pressure sensor VSV does not operate as specified, go to next step. If vapor pressure sensor VSV operates as specified, go to step 16).
  13. Remove charcoal canister assembly. Remove vapor pressure sensor VSV. Using ohmmeter, measure resistance between vapor pressure sensor VSV terminals. With vapor pressure sensor VSV temperature at 68°F (20°C), resistance should be 33-39 ohms. Measure resistance between each terminal and body of valve. Resistance should be infinite. If resistance is as specified, go to next step. If resistance is not as specified, replace vapor pressure sensor VSV and charcoal canister. After replacing components clean vacuum hoses between vapor pressure sensor VSV and vapor pressure sensor, and between vapor pressure sensor VSV and charcoal canister.
  14. Using fused jumper wires, apply battery voltage and ground to vapor pressure sensor VSV terminals. Apply compressed air to vapor pressure sensor VSV port "E". Air should flow from port "F". (Scheme 10) Disconnect fused jumper wires. Air should flow from port "G". If vapor pressure sensor VSV does not operate as specified, replace vapor pressure sensor VSV and charcoal canister. After replacing components clean vacuum hoses between vapor pressure sensor VSV and vapor pressure sensor, and between vapor pressure sensor VSV and charcoal canister. If vapor pressure sensor VSV operates as specified, go to next step.
  15. Check for open or short circuit in wiring harness between EFI main relay, vapor pressure sensor VSV and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair as necessary. If wiring harness is okay, replace ECM and retest.
  16. Connect Lexus scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) Disconnect vapor pressure sensor VSV connector. Using scan tool, select ACTIVE TEST mode. Start and run engine. Using scan tool, turn EVAP VSV on. Access ECM at left front of engine compartment. Backprobing, measure voltage between ECM E5 connector terminal No. 18 (Blue/Yellow wire) and ECM E3 connector terminal No. 18 (Brown wire). (Scheme 8) If voltage is 2 volts or less, go to step 18). If voltage is not 2 volts or less, go to next step.
  17. Check for correct routing, damage, looseness and blockage in vacuum hoses between charcoal canister and vapor pressure sensor VSV, and between vapor pressure sensor VSV and vapor pressure sensor. Repair as necessary. If vacuum hoses are okay, go to next step.
  18. Remove fuel cap. Disconnect vapor pressure sensor VSV. Using scan tool, select ACTIVE TEST mode. Start and run engine. Using scan tool turn EVAP VSV on for 5 seconds. Turn EVAP VSV off. Backprobing, measure voltage between ECM E5 connector terminal No. 18 (Blue/Yellow wire) and ECM E3 connector terminal No. 18 (Brown wire). If voltage is 2.5 volts or less, go to next step. If voltage is not 2.5 volts or less, replace charcoal canister.
  19. Remove charcoal canister. Visually inspect charcoal canister for cracks or damage. Close purge port. (Scheme 11) Apply.26 psi (.02 kg/cm 2 ) of compressed air to EVAP port of charcoal canister. Air should flow from air drain port.
  20. Close purge port and air drain port. (Scheme 11) Apply.26 psi (.02 kg/cm 2 ) of compressed air to EVAP port of charcoal canister. Air should not flow from air inlet port.
  21. Apply 1.01 in. Hg of vacuum to purge port. (Scheme 11) Vacuum should not decrease with air inlet port closed and should decrease with air inlet port open.
  22. Close inlet port. (Scheme 11) Connect vacuum gauge to purge port. Apply 1.01 in. Hg of vacuum to EVAP port. Vacuum should exist at purge port. If charcoal canister does not operate as specified, replace as necessary. If charcoal canister is okay, replace ECM and retest.
  1. Check for loose or disconnected connectors at EVAP VSV, vapor pressure sensor VSV and vapor pressure sensor. Repair as necessary. If all connectors are okay, go to next step.
  2. Check for correct routing, damage, looseness and blockage in vacuum hoses between vapor pressure sensor and vapor pressure sensor VSV, and between vapor pressure sensor VSV and charcoal canister. Also check vacuum hoses between EVAP VSV and charcoal canister, between EVAP VSV and air resonator, and between intake manifold and charcoal canister. Repair as necessary. If vacuum hoses are okay, go to next step.
  3. Access ECM at left front of engine compartment. Turn ignition on. Backprobing, measure voltage between terminals No. 2 (Blue/Yellow wire) and No. 18 (Brown wire) at ECM E3 connector. (Scheme 8) 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.
  4. Backprobing, measure voltage between terminals No. 18 (Blue/Yellow wire) at ECM E5 connector and No. 18 (Brown wire) at ECM E3 connector. Disconnect vacuum hose from vapor pressure sensor. Sensor is located next 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 1.2-19.7 in. Hg applied, go to step 6). If voltage is not as specified, go to next step.
  5. Check for an open or short circuit in wiring harness and connector between vapor pressure sensor and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair as necessary. If wiring harness and connector are okay, replace vapor pressure sensor and retest.
  6. Turn ignition on. Backprobing, connect fused jumper wire between ground and ECM E3 connector terminal No. 7 (Black/Yellow wire). Apply compressed air to EVAP VSV port "E". (Scheme 9) Air should flow from port "F". Disconnect fused jumper wire. Air should not flow from port "F". If EVAP VSV functions as specified, go to step 10). If EVAP VSV does not function as specified, go to next step.
  7. Remove EVAP VSV. Using ohmmeter, measure resistance between VSV terminals. With VSV temperature at 68°F (20°C), resistance should be 33-39 ohms. Measure resistance between each terminal and body of valve. Resistance should be infinite. If resistance is as specified, go to next step. If resistance is not as specified, replace EVAP VSV and charcoal canister. After replacing components clean vacuum hoses between throttle body and EVAP VSV, and between EVAP VSV and charcoal canister.
  8. 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 9) Disconnect fused jumper wires. Air should not flow from port "F". If EVAP VSV does not operate 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.
  9. Check for open or short circuit in wiring harness and connector between EFI main relay, EVAP VSV and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair as necessary. If wiring harness is okay, replace ECM and retest.
  10. Access ECM at left front of engine compartment. Turn ignition on. Backprobing ECM harness connector, connect fused jumper wire between ground and ECM E7 connector terminal No. 13 (White/Red wire). (Scheme 8) Apply compressed air to vapor pressure sensor VSV port "E". Air should flow from port "F". (Scheme 10) Disconnect fused jumper wire. Air should flow from port "G". If vapor pressure sensor VSV functions as specified, go to next step. If vapor pressure sensor VSV does not function as specified, go to step 15).
  11. Remove charcoal canister. Visually inspect charcoal canister for cracks or damage. Close purge port of charcoal canister. (Scheme 11) Apply.26 psi (.02 kg/cm 2 ) of compressed air to EVAP port of charcoal canister. Air should flow from air drain port.
  12. Close purge port and air drain port. (Scheme 11) Apply.26 psi (.02 kg/cm 2 ) of compressed air to EVAP port of charcoal canister. Air should not flow from air inlet port.
  13. Apply 1.01 in. Hg of vacuum to purge port. (Scheme 11) Vacuum should not decrease with air inlet port closed and should decrease with air inlet port open.
  14. Close inlet port. (Scheme 11) Connect vacuum gauge to purge port. Apply 1.01 in. Hg of vacuum to EVAP port. Vacuum should exist at purge port. If charcoal canister does not operate as specified, replace as necessary.
  15. Remove charcoal canister. Remove vapor pressure sensor VSV. Using ohmmeter, measure resistance between vapor pressure sensor VSV terminals. With vapor pressure sensor VSV temperature at 68°F (20°C), resistance should be 33-39 ohms. Measure resistance between each terminal and body of valve. Resistance should be infinite.
  16. If resistance is not as specified, replace vapor pressure sensor VSV and charcoal canister. After replacing components clean vacuum hoses between vapor pressure sensor VSV and vapor pressure sensor, and between vapor pressure sensor VSV and charcoal canister. If resistance is as specified, go to next step.
  17. Using fused jumper wires, apply battery voltage and ground to vapor pressure sensor VSV terminals. Apply compressed air to vapor pressure sensor VSV port "E". Air should flow from port "F". (Scheme 10) Disconnect fused jumper wires. Air should flow from port "G". If vapor pressure sensor VSV operates as specified, go to step 19).
  18. If vapor pressure sensor VSV does not operate as specified, replace vapor pressure sensor VSV and charcoal canister. After replacing components clean vacuum hoses between vapor pressure sensor VSV and vapor pressure sensor, and between vapor pressure sensor VSV and charcoal canister.
  19. Check for open or short circuit in wiring harness and connectors between EFI main relay, vapor pressure sensor VSV and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair as necessary. If wiring harness is okay, replace ECM and retest.

Scheme 9

Scheme 9
Scheme 9

Scheme 10

Scheme 10
Scheme 10

Scheme 11

Scheme 11
Scheme 11
  1. Access ECM at left front of engine compartment. Turn ignition on. Backprobing, measure voltage between terminals No. 2 (Blue/Yellow wire) and No. 18 (Brown wire) at ECM E3 connector. (Scheme 8) 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.
  2. Backprobing, measure voltage between terminals No. 18 (Blue/Yellow wire) at ECM E5 connector and No. 18 (Brown wire) at ECM E3 connector. Disconnect vacuum hose from vapor pressure sensor. Sensor is located next fuel tank. Connect a vacuum pump to sensor. If voltage is 2.9-3.7 volts without vacuum applied, and.5 volt with 1.2-19.7 in. Hg vacuum applied, replace ECM and retest system. If voltage is not as specified, go to next step.
  3. Check for an open or short in wiring harness and connectors between vapor pressure sensor and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) 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. (Scheme 5) Start engine. Turn scan tool on. Drive vehicle. If vehicle speed matches scan tool speed value, go to next step. If vehicle speed does not match scan tool speed value, replace ECM and retest system.
  2. Check speedometer operation. If speedometer is operating properly, go to next step. If speedometer is not operating properly, check for open or short in VSS circuit. See ENGINE SENSORS & SWITCHES in «SYSTEM/COMPONENT TESTS»(ref-22514) article. Repair as necessary.
  3. Access ECM at left front of engine compartment. Disconnect ECM E4 connector. Using an ohmmeter, measure resistance between ECM E4 harness connector terminals No. 5 (Blue/Yellow wire) and No. 11 (Red/Blue wire). (Scheme 8) 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 appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair wiring as necessary.

The idle speed is controlled by the Electric Throttle Control System (ETCS). The ETCS is composed of throttle motor, magnetic clutch, TP sensor, accelerator pedal position sensor, ECM and throttle body. The ECM controls throttle motor to adjust throttle valve opening angle. DTC P0505 is set if idle speed continues to vary greatly from target speed. Possible causes are

  1. ETCS.
  2. Air intake hose.

Scheme 12

Scheme 12: Diagnosis & Repair
Scheme 12: Diagnosis & Repair
  1. Retrieve trouble codes. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22508-S22034545892001010300000) 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. Ensure all accessories are off. Ensure throttle linkage moves smoothly. Turn ignition on. Rotate accelerator pedal position sensor lever and listen for running sound from throttle motor. Ensure friction sound does not exist. If running sound exists, go to step 5). If running sound does not exist, check throttle control motor. See «SYSTEM/COMPONENT TESTS»(ref-22514) article.
  4. If throttle control motor is okay, check for open or short circuit in wiring harness between throttle control motor and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair wiring as necessary. If wiring is okay, go to next step.
  5. Using Lexus scan tool, connect Lexus scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) Switch Lexus scan tool to CURRENT DATA. Ensure MIL does not illuminate. Rotate accelerator pedal position sensor lever to full open position. THROTTLE POS on Lexus scan tool should indicate 60 percent or more. If results are as specified, go to step 7). If results are not as specified, check accelerator pedal position sensor. See «SYSTEM/COMPONENT TESTS»(ref-22514) article.
  6. If accelerator pedal position sensor is okay, check for open or short circuit in wiring harness between accelerator pedal position sensor and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair wiring as necessary.
  7. Clear trouble codes. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-22508-S03887009072001010300000) under SELF-DIAGNOSTIC SYSTEM. Start engine and ensure MIL does not illuminate. Allow engine to reach normal operating temperature. Ensure all accessories are off. Place transmission in Neutral position. Turn A/C on and then off and check idle speed. Idle speed should be between 700-800 with A/C on. Idle speed should be between 650-750 with A/C off.
  8. With engine idling, pinch air assist hose located next to throttle motor. (Scheme 12) Idle speed should drop and return back to normal. If idle speed changes as specified, go to next step. If idle speed does not change as specified, check throttle body. If throttle body is okay, check for open or short circuit in wire harness. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair wiring as necessary. If wiring is okay, go to next step.
  9. Drive vehicle to ensure vehicle performs properly. Retrieve trouble codes. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22508-S22034545892001010300000) under SELF-DIAGNOSTIC SYSTEM. If DTC P0505 is displayed or vehicle does not perform as specified, replace ECM and retest.
  1. Connect Lexus scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) 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.3-.9 volt at VPA circuit and 1.8-2.7 volts at VPA2 circuit with a fully closed throttle. Depress accelerator pedal to floor (WOT). Accelerator pedal position sensor voltage should be 3.2-4.8 volts at VPA circuit and 4.7-5.1 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, measure voltage between ECM E3 connector terminals No. 2 (Blue/Yellow wire) and No. 18 (Brown wire). (Scheme 8) 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, measure voltage between ECM E3 connector terminals No. 15 (Blue wire), No. 16 (Blue/Red wire) and No. 18 (Brown wire). With fully closed throttle, VPA circuit voltage should be.3-.9 volt and VPA2 voltage should be 1.8-2.7 volts. With wide open throttle (WOT), VPA circuit voltage should be 3.2-4.8 volts and VPA2 circuit voltage should be 4.7-5.1 volts. If voltage is not as specified, go to next step. If voltage is as specified, replace ECM and retest.
  4. Check accelerator pedal sensor operation. See «SYSTEM/COMPONENT TESTS»(ref-22514) article. Replace accelerator pedal sensor as necessary. If accelerator pedal sensor is okay, check for short or open circuit in wiring harness and sensor connector between ECM E3 connector and accelerator pedal sensor. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair wiring as necessary.
  1. Access ECM at left front of engine compartment. Turn ignition on. Backprobing, measure voltage between ECM E3 connector terminals No. 2 (Blue/Yellow wire) and No. 18 (Brown wire). (Scheme 8) 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, measure voltage between ECM E3 connector terminals No. 15 (Blue wire), No. 16 (Blue/Red wire) and No. 18 (Brown wire). With fully closed throttle, VPA circuit voltage should be.3-.9 volt and VPA2 circuit voltage should be 1.8-2.7 volts. With wide open throttle (WOT), VPA circuit voltage should be 3.2-4.8 volts and VPA2 circuit voltage should be 4.7-5.1 volts. If voltage is not as specified, go to next step. If voltage is as specified, replace ECM and retest.
  3. Check accelerator pedal sensor operation. See «SYSTEM/COMPONENT TESTS»(ref-22514) article. Replace accelerator pedal sensor as necessary. If accelerator pedal sensor is okay, check for short or open circuit in wiring harness and sensor connector between ECM E3 connector and accelerator pedal sensor. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair wiring as necessary.

The accelerator pedal sensor is a 2 variable resistor sensor that monitors throttle opening and accelerator pedal sensor malfunction. The accelerator pedal sensor determines vehicle accelerator pedal position. ECM controls throttle motor and electromagnetic clutch based on the signal from accelerator pedal sensor. If DTC P1121 is set, ECM shuts down power to throttle control motor and electromagnetic clutch.

DTC P1121 is set when ECM consistently detects difference between VPA and VPA2 circuits out of tolerance. Possible causes are

  1. Accelerator pedal sensor.
  2. ECM.

Replace accelerator pedal sensor and retest.

  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 and No. 2. (Scheme 13) Resistance should be.3-100 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. Check for open or short circuit in wiring harness or connector between throttle control motor and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair wiring as necessary. If wiring and connectors are okay, replace ECM and retest.

Scheme 13

Scheme 13
Scheme 13
  1. Connect Lexus scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) Turn ignition on. Turn scan tool on. Using Lexus scan tool, monitor magnetic clutch current value. If magnetic clutch current is.8-1 amp, go to next step. If magnetic clutch current is not.8-1 amp, go to step 4).
  2. Disconnect throttle control motor and magnetic clutch connector. Using an ohmmeter, measure resistance between throttle control motor connector terminals No. 3 and No. 4. (Scheme 13) Resistance should be 4.2-5.2 ohms at 68°F (20°C). If resistance is at specified, go to next step. If resistance is not as specified, replace throttle control motor.
  3. Check for open or short circuit and connector in wiring harness between magnetic clutch and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair wiring as necessary. If wiring is okay, go to next step.
  4. Clear trouble codes. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-22508-S03887009072001010300000) under SELF-DIAGNOSTIC SYSTEM. Turn ignition on. Start engine. Turn ignition off for 3 seconds. Turn ignition on. Retrieve trouble codes. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22508-S22034545892001010300000) under SELF-DIAGNOSTIC SYSTEM. If DTC P1126 is displayed, replace ECM and retest. If DTC P1126 is not displayed, replace throttle control motor and retest.
  1. Check ETCS (15 amp) fuse. ETCS fuse is located in engine compartment fuse/relay box, at right side of engine compartment. 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 appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair wiring as necessary.
  2. Access ECM at left front of engine compartment. Backprobing, measure voltage between ground and ECM E6 connector terminal No. 7 (Violet/Yellow wire). (Scheme 8) If voltage is 9-14 volts, replace ECM and retest. If voltage is not 9-14 volts, check circuits in wiring harness between battery voltage, ETCS fuse and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair wiring as necessary.

Throttle control motor opens and closes throttle valve as commanded by the ECM. ECM determines throttle valve position using throttle position sensor. If DTC P1128 is set, ECM shuts down power to throttle control motor and electromagnetic clutch.

DTC P1128 is set when throttle control motor locks. Possible causes are

  1. Throttle control motor.
  2. Throttle body assembly.
  3. ECM.

Check throttle control motor. See DTC P1125 THROTTLE CONTROL MOTOR CIRCUIT MALFUNCTION. Replace as necessary. If throttle control motor is okay, remove intake air duct. Visually inspect throttle valve for foreign material. If throttle valve is clean, replace throttle body.

Replace ECM. Retrieve trouble codes. See RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. If DTC P1129 is displayed, replace throttle body and retest.

  1. Check for spark at misfiring cylinder. See IGNITION CHECKS in «BASIC TESTING»(ref-22506) 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 circuit (Black wire) between ECM E2 connector and ignitor. Ignitor is located on left side of engine compartment, near shock tower. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair as necessary. If circuit is okay, go to next step.
  3. Disconnect 10-pin ignitor connector. Access ECM at left front of engine compartment. Turn ignition on. Backprobing, measure voltage between ground and terminal No. 25 (Black wire) at ECM E2 connector. (Scheme 8) If voltage is 4.5-5.5 volts, replace ignitor. If voltage is not 4.5-5.5 volts, replace ECM and retest.
  4. Check for open or short in IGT circuits (Black/Yellow, Black/Blue or Black/Red wire) between ECM E2 connector and ignitor. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair as necessary. If circuit is okay, go to next step.
  5. Access ECM at left front of engine compartment. Backprobe, measure voltage between ground and terminal No. 11 (Black/Yellow wire), No. 12 (Black/Blue wire) or No. 13 (Black/Red wire) at ECM E2 connector while cranking engine. If voltage is.1-4.5 volts, go to next step. If voltage is not.1-4.5 volts, replace ECM and retest.
  6. Disconnect 10-pin ignitor connector. Backprobing, measure voltage between ground and terminal No. 11 (Black/Yellow wire), No. 12 (Black/Blue wire) or No. 13 (Black/Red wire) at ECM E2 connector while cranking engine. If voltage is.1-5 volts, go to next step. If voltage is not.1-5 volts, replace ECM and retest.
  7. Turn ignition switch to ON position and then to START position. Measure voltage between ground and terminal No. 9 (Black/White wire) at ignitor wiring harness connector. If voltage is not 9-14 volts, go to next step. If voltage is 9-14 volts, check and repair ignitor power source circuit. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article.
  8. Check for an open or short in wiring harness or connector between ignition switch and ignition coil, and between ignition coil and ignitor. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair wiring as necessary. If wiring is okay, go to next step.
  9. Check EFI main relay. (Scheme 14) Repair as necessary, If EFI main relay is okay check ignition coils. Repair as necessary. If ignition coils are okay, replace ignitor.

Scheme 14

Scheme 14
Scheme 14
  1. Check valve timing. See ENGINES article in the ENGINE MECHANICAL section. 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. (Scheme 5) Select VVT from scan tool ACTIVE TEST menu. Using scan tool, turn OCV on and off. If engine speed does not change with OCV off and changes (rough idle) with OCV on, VVT system is okay at this time. A foreign object may have been caught in some part of VVT system. ECM will control VVT system to remove foreign object. If engine speed does not change as specified, go to next step.
  3. Access ECM at left front of engine compartment. Backprobe ECM E2 connector. Start engine. Using oscilloscope, check waveform pattern between ECM E2 connector terminals No. 17 (Red/White wire) and No. 18 (White/Red wire). (Scheme 8) Slowly increase engine speed. Waveform frequency "A" should lengthen as engine speed increases. (Scheme 15) If readings are not as specified, replace ECM and retest. If readings are as specified, go to next step.
  4. Remove timing belt cover and timing belt. See ENGINES article in the ENGINE MECHANICAL section. Remove OCV. Place a shop towel under OCV cylinder head opening. Rotate 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 VVT pulley/gear assembly and go to next step. If oil drains from opening, go to next step.
  5. With 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. 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 OCV and go to next step. If OCV plunger moves as specified, go to next step.
  6. Check blockage in OCV. Check oil check valve and oil pipe located under OCV. Repair an necessary. If components are okay, go to next step.
  7. Clear DTCs. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-22508-S03887009072001010300000) under SELF-DIAGNOSTIC SYSTEM. Duplicate driving conditions under which DTC P1349 was set. Retrieve DTCs. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22508-S22034545892001010300000) under SELF-DIAGNOSTIC SYSTEM. If DTC P1349 is displayed, replace ECM and retest. If DTC P1349 is not displayed, VVT system is okay at this time. A foreign object may have been caught in some part of VVT system. ECM will control VVT system to remove foreign object.
  1. Check valve timing. See TIMING BELT in ENGINES article in the ENGINE MECHANICAL section. 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 OCV 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 16) If engine speed does not change with OCV disconnected and changes (rough idle) with fused jumper wires connected, go to next step. If results are not as specified, go to step 4).
  3. Access ECM at left front of engine compartment. Backprobe ECM E2 connector. Start engine. Using oscilloscope, check waveform pattern between ECM E2 connector terminals No. 17 (Red/White wire) and No. 18 (White/Red wire). (Scheme 8) Slowly increase engine speed. Waveform frequency "A" should lengthen as engine speed increases. (Scheme 15) If readings are not as specified, replace ECM and retest. If readings are as specified, VVT system is okay at this time. A foreign object may have been caught in some part of VVT system. ECM will control VVT system to remove foreign object. If readings are not as specified, replace ECM and retest.
  4. Remove timing belt cover and timing belt. See TIMING BELT in ENGINES article in the ENGINE MECHANICAL section. Remove OCV. Place a shop towel under OCV cylinder head opening. Rotate 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 VVT pulley/gear assembly and go to next step. If oil drains from head opening, go to next step.
  5. With 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 16) 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 OCV and go to next step. If OCV plunger moves as specified, go to next step.
  6. Check blockage in OCV. Check oil check valve and oil pipe located under OCV. Repair an necessary. If components are okay, go to next step.
  7. Clear DTCs. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-22508-S03887009072001010300000) under SELF-DIAGNOSTIC SYSTEM. Duplicate driving conditions under which DTC P1349 was set. Retrieve DTCs. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22508-S22034545892001010300000) under SELF-DIAGNOSTIC SYSTEM. If DTC P1349 is not displayed, go to next step. If DTC P1349 is not displayed, VVT system is okay at this time. A foreign object may have been caught in some part of VVT system. ECM will control VVT system to remove foreign object.

Scheme 15

Scheme 15
Scheme 15

Scheme 16

Scheme 16
Scheme 16
  1. Check stoplights. If stoplights do not function properly, repair as necessary and retest system. 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. (Scheme 5) 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, measure voltage between ground and terminal No. 6 (Green/White wire) at ECM E5 connector. (Scheme 8) With brake pedal depressed, voltage should be 7.5-14.0 volts. With brake pedal released, voltage should be less than 1.5 volt. 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 appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair as necessary and retest system. If wiring harness is okay, replace ECM. Retest system.
  1. Access ECM at left front of engine compartment. Backprobing, measure voltage between ground and terminal No. 1 (Black/Yellow wire) at ECM E6 connector. (Scheme 8) 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 fuse (15-amp) from junction block No. 2, located at right side of engine compartment. 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 appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article.

Replace ECM.

See MULTIPLEX CONTROL SYSTEM article in the ACCESSORIES & EQUIPMENT section.

  1. Start and run engine. Allow engine to reach normal operating temperature. Connect Lexus scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) Select VVT from scan tool ACTIVE TEST menu. Using scan tool, turn OCV on and off. If engine speed does not change with OCV off and changes (rough idle) with OCV on, VVT system is okay at this time. A foreign object may have been caught in some part of VVT system. ECM will control VVT system to remove foreign object. If engine speed does not change as specified, go to next step.
  2. With engine running. Disconnect OCV 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 16) If engine speed does not change with OCV disconnected and changes (rough idle) with fused jumper wires connected, go to next step. If results are not as specified, replace OCV and retest.
  3. Access ECM at left front of engine compartment. Backprobe ECM E2 connector. Start engine. Using oscilloscope, check waveform pattern between ECM E2 connector terminals No. 17 (Red/White wire) and No. 18 (White/Red wire). (Scheme 8) Slowly increase engine speed. Waveform frequency "A" should lengthen as engine speed increases. (Scheme 15) 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 and connector in wire harness between OCV and ECM E2 connector. Repair as necessary. If circuit and connector are okay, problem is intermittent.
  1. Start and run engine. Allow engine to reach normal operating temperature. Disconnect OCV 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 16) If engine speed does not change with OCV disconnected and changes (rough idle) with fused jumper wires connected, go to next step. If results are not as specified, replace OCV and retest.
  2. Access ECM at left front of engine compartment. Backprobe ECM E2 connector. Start engine. Using oscilloscope, check waveform pattern between ECM E2 connector terminals No. 17 (Red/White wire) and No. 18 (White/Red wire). (Scheme 8) Slowly increase engine speed. Waveform frequency "A" should lengthen as engine speed increases. (Scheme 15)If readings are not as specified, replace ECM and retest. If readings are as specified, VVT system is okay at this time.
  3. Check for an open or short circuit and connector in wire harness between OCV and ECM E2 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 Lexus scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) 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 Lexus 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, check for battery voltage between ground and appropriate ECM connector terminal at each gear position. (Scheme 8) See «IDENTIFYING ECM CONNECTORS & TERMINALS»(ref-22508-S07032876902001010300000) table. If battery voltage exist 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 (Wire Color) Park E5 No. 26 (Red/White) Reverse (1) E5 No. 16 (Red/Black) Neutral E3 No. 13 (Green/Red) Drive E5 No. 17 (Yellow/Black) 4 E5 No. 7 (Yellow/Green) 3 E3 No. 20 (Green) 2 E3 No. 21 (Green/Black) Low E2 No. 14 (Red/Yellow) (1) Voltage should be less doe to back up light illuminating.
  3. Raise and support vehicle. Disconnect park/neutral position switch Gray 10-pin connector. Move shift lever through all gear positions one at a time. Check for continuity between appropriate terminals at park/neutral position switch Gray 10-pin connector at each gear position. (Scheme 17) See «IDENTIFYING PARK/NEUTRAL SWITCH TERMINALS»(ref-22508-S33744655172001010300000) table. If continuity does not exist as specified, replace park/neutral position switch and retest. If continuity exists as specified, check for short or open circuit in wire harness and connector between battery and park/neutral position switch, and park/neutral position switch and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120936) article. Repair as necessary.
Gear PositionTerminal Nos.
Park4-7 & 5-6
Reverse4-8
Neutral4-10 & 5-6
Drive4-9
44-9
32-4
Low & 24-3

IDENTIFYING PARK/NEUTRAL SWITCH TERMINALS

Scheme 17

Scheme 17
Scheme 17

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