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Engine Controls - Tests W/codes: Diagnosis Lexus ES XV20

Testing & Diagnostics 9 illustrations ~12263 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-120548) article. See «ECM LOCATION»(ref-22507-S32619943152001010300000) .
  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-22507-S14440867492001010300000) .

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-22507-S14440867492001010300000) .
  3. Clear Trouble Codes Clear codes using scan tool. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-22507-S32038402032001010300000) .
  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) IDENTIFICATIONS»(ref-22507-S30759744782001010300000) . 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-22507-S32038402032001010300000) . 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-22507-S21556237932001010300000) 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-22507-S30759744782001010300000). For more information on freeze-frame data, see «FREEZE-FRAME DATA»(ref-22507-S07218198172001010300000) under INTRODUCTION. For information on 2-trip detection logic codes, see «DETECTION LOGIC»(ref-22507-S18944937812001010300000) under INTRODUCTION.
  5. After repairs for DTC have been completed, DTCs must be cleared from ECM memory. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-22507-S32038402032001010300000).

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-22507-S30759744782001010300000). For more information on freeze-frame data, see «FREEZE-FRAME DATA»(ref-22507-S07218198172001010300000) under INTRODUCTION. For information on 2-trip detection logic codes, see «DETECTION LOGIC»(ref-22507-S18944937812001010300000) under INTRODUCTION.
  6. After repairs for DTC have been completed, DTC must be cleared from ECM memory. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-22507-S32038402032001010300000).

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.

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-120548) 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-22507-S06631356712001010300000) table. (Scheme 6) If voltage and resistance readings are not as specified, check wiring circuit. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article.

Note. Terminal No. 7 on DLC No. 3 provides the pulse generation during the information transmission from the Engine Control Module (ECM).

Terminal 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 6

Scheme 6
Scheme 6

DIAGNOSTIC TESTS

Note. For component locations, see appropriate illustration in SYSTEM/COMPONENT TESTS article.

Note. For wire color and circuit identification, 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, keeping ignition timing and injection volume constant. DTC P0100 is set when ECM detects a open or short circuit with engine speed at 4000 RPM or less for more than 3 seconds. Possible causes are

  1. MAF Open Or Short Circuit
  2. MAF Sensor
  3. ECM

Diagnosis & Repair

  1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) Turn ignition on. Turn on scan tool. Start engine and allow it to idle. Monitor MAF rate. If scan tool reading is 0.0 gm/sec., go to next step. If reading is 271.0 gm/sec. once engine is at normal operating temperature, go to step 5).
  2. Disconnect MAF sensor connector. Turn ignition on. Using voltmeter, measure voltage between ground and terminal No. 4 (Black/Yellow wire) at MAF sensor wiring 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/Orange wire between MAF sensor connector and EFI relay. EFI relay is located in junction block at left side of engine compartment.
  3. Access ECM behind glove box. Start engine. Backprobing ECM connector, measure voltage between ground and terminal No. 10 (Pink wire) at ECM E8 connector. (Scheme 7) If voltage is 1.1-1.5 volts, replace ECM and retest system.
  4. If voltage is not 1.1-1.5 volts, locate and repair open or short circuit in Pink wire between MAF sensor and ECM E8 connector. If Pink wire is okay, replace MAF sensor and retest system.
  5. Access ECM behind glove box. Turn ignition off. Backprobing ECM E8 connector, check for continuity between ground and terminal No. 19 (Red/Black wire) at ECM E8 connector. (Scheme 7) If continuity does not exist, replace ECM and retest system. If continuity exists, go to next step.
  6. Check for an open in wiring harness between MAF sensor and ECM E8 connector. Repair as necessary. If wiring is okay, replace MAF sensor.

Scheme 7

Scheme 7
Scheme 7

MAF sensor uses a platinum hot wire maintained at a constant temperature. Airflow past sensor affects temperature and current flow through sensor. If DTC P0101 is set, ECM will operate in fail-safe mode, keeping ignition timing and injection volume constant. DTC P0101 is set when throttle valve is fully closed, MAF sensor output is more than 2.2 volts, and Engine Coolant Temperature (ECT) sensor indicates more than 158°F (70°C) 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 volts or more, and MAF sensor output is less than 1.06 volts for 10 seconds or more at engine speed or 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 system. If other codes are displayed, diagnose and repair those codes first and retest system.

  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 fused jumper wire between terminals No. 1 (Blue/Yellow 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, ensure MAF connector is okay. If connector is okay, replace MAF sensor and retest system. If temperature displayed is less than 284°F (140°C), turn ignition off. Remove fused jumper wire. Access ECM behind glove box. Backprobing, connect fused jumper wire between terminals No. 22 (Blue/Yellow wire) and No. 18 (Brown wire) at ECM E8 connector. (Scheme 7)
  4. If temperature displayed on scan tool is 284°F (140°C) or more, check and repair open in Blue/Yellow or Brown wire between MAF harness connector and ECM E8 connector. If temperature displayed on scan tool is not 284°F (140°C) or more, replace ECM and retest system.
  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 system. If temperature displayed is not -40°F (-40°C), turn ignition off and go to next step.
  6. Access ECM behind glove box. Disconnect ECM E8 connector. Turn ignition on. If temperature displayed is -40°F (-40°C), locate and repair short circuit in wiring harness between MAF sensor and ECM. (Scheme 7) If temperature displayed by scan tool is not -40°F (-40°C), replace ECM and retest system.
  1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) Turn ignition on. Turn scan tool on. Using scan tool, monitor E CT sensor temperature. If temperature displayed is same as actual coolant temperature, check component and ECM connections. 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 harness connector. Connect a fused jumper wire between terminals No. 2 (Green/Black wire) and No. 1 (Brown wire) at ECT sensor harness connector. Turn ignition on. Using scan tool, monitor ECT sensor temperature.
  3. If temperature displayed is 284°F (140°C) or more, ensure ECT connector is okay. If connector is okay, replace ECT sensor and retest system. If temperature displayed is less than 284°F (140°C), turn ignition off. Remove fused jumper wire. Access ECM behind glove box. Backprobing, connect fused jumper wire between terminals No. 14 (Green/Black wire) and No. 18 (Brown wire) at ECM E8 connector. (Scheme 7)
  4. If temperature displayed on scan tool is 284°F (140°C) or more, check and repair open in Green/Black or Brown wire between ECT harness connector and ECM E8 connector. If temperature displayed on scan tool is not 284°F (140°C) or more, replace ECM and retest system.
  5. Turn ignition off. Disconnect ECT sensor harness connector. Turn ignition on. If temperature displayed on scan tool is -40°F (-40°C), replace ECT sensor and retest system. If temperature displayed is not -40°F (-40°C), turn ignition off.
  6. Access ECM behind glove box. Disconnect ECM E8 connector. Turn ignition on. If temperature displayed is -40°F (-40°C), locate and repair short circuit in wiring harness between ECT sensor and ECM E8 connector. (Scheme 7) If temperature displayed by scan tool is not -40°F (-40°C), replace ECM and retest system.

The ECT sensor is a thermistor that monitors coolant temperature. If DTC P0116 is set, ECM will operate in a fail-safe mode, in which engine coolant is assumed to be 176°F (80°C). DTC P0116 is set when after engine has been running for 20 minutes ECM detects a temperature of less than 19.4°F (-7°C) on THW circuit, and actual engine coolant temperature is 95°F (35°C). DTC P0116 is also set when after engine has been running for 5 minutes ECM detects a temperature of less than 50°F (10°C), or detects a temperature equal to or grater than 19.4°F (-7°C) on THW circuit, and actual engine coolant temperature is 95°F (35°C). DTC P0116 is set when after engine has been running for 2 minutes ECM detects a temperature of more than or equal to 50°F (10°C) on THW circuit, and actual engine coolant temperature is 95°F (35°C). Possible causes are

  1. ECT Sensor
  2. Faulty Cooling System

Note. If DTCs P0115 and P0116 are output together, diagnose DTC P0115 first. Inspect engine coolant temperature circuit for an open. Repair as necessary. See appropriate wiring diagram in SYSTEM WIRING DIAGRAMS article.

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 system. If only DTC P0116 is displayed, check cooling system thermostat. Replace thermostat as necessary and retest system. If thermostat is okay, replace ECT sensor and retest system.

  1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) Turn ignition on. Turn scan tool on. Using scan tool, monitor throttle valve opening percentage. Opening percentage should be approximately 10 with fully closed throttle. Depress accelerator pedal to floor (WOT). Opening percentage should be approximately 75. If percentages are within specification, check all connections. Problem may be intermittent. If percentages are not within specification, go to next step.
  2. Disconnect TP sensor harness connector. Turn ignition on. Using voltmeter, measure voltage between ground and Yellow wire at TP sensor harness connector. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, go to step 5).
  3. Turn ignition off. Using ohmmeter, measure resistance between terminals No. 1 (Yellow wire) and No. 2 (Brown wire) at TP sensor component connector. Resistance should be 2500-5900 ohms. Measure resistance between terminals No. 2 (Brown wire) and No. 3 (Blue wire). Resistance should be 200-6300 ohms with throttle fully closed, and 2000-10,200 ohms with throttle fully open. If any readings are not within specification, replace TP sensor. If all readings are within specification, go to next step.
  4. Connect TP sensor harness connector. Access ECM harness connectors behind glove box. Turn ignition on. Backprobing ECM harness connector, measure voltage between terminals No. 23 (Blue wire) and No. 18 (Brown wire) at ECM E8 connector. (Scheme 7) Voltage should be.3-1.0 volt with throttle fully closed, and 2.7-5.2 volts with throttle fully open (WOT). If voltages are as specified, replace ECM and retest system. If voltages are not as specified, locate and repair open or short in Blue wire between TP sensor and ECM E8 connector.
  5. Access ECM harness connectors behind glove box. Turn ignition on. Backprobing ECM harness connector, measure voltage between terminals No. 2 (Yellow wire) and No. 18 (Brown wire) at ECM E8 connector. If voltage is 4.5-5.5 volts, locate and repair open in Yellow wire between TP sensor and ECM E8 connector. If voltage is not 4.5-5.5 volts, replace ECM and retest system.

The TP sensor is a variable resistor that monitors throttle opening. TP sensor is mounted in throttle body. The ECM determines vehicle driving condition and adjusts air/fuel mixture accordingly. DTC is set when after vehicle speed has exceeded 19 MPH and output value of TP sensor was out of range at vehicle speeds of 0-19 MPH. Possible cause is

  1. Throttle Position (TP) sensor.

Retrieve trouble codes. See RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. If only DTC P0121 is displayed, replace TP sensor and retest system. If other codes are displayed, diagnose and repair those codes first and retest system.

  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 each oxygen sensor. 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 oxygen sensors, replace ECM and retest system. If either oxygen sensor does not display a rich signal, check for a misfire in one or more cylinders. See «DTC P0300-P0306»(ref-22507-S38485668582001010300000). Repair as necessary. If no misfire is detected, check for open or short circuit in wiring harness between ECM and suspect oxygen sensor. Repair as necessary. If wiring harness is okay, replace suspect oxygen sensor and retest system.
  1. Retrieve trouble codes. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22507-S14440867492001010300000) under SELF-DIAGNOSTIC SYSTEM. If only DTC P0125 is displayed, check for open or short in harness and connector between ECM and suspect oxygen sensor. If harness and connector are okay, check resistance of suspect oxygen sensor heater circuit. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. If heater circuit is okay, go to next step. If other codes are displayed, diagnose and repair those codes first and retest system.
  2. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) Start engine and run engine at 2500 RPM for 90 seconds. Using scan tool, monitor each oxygen sensor. Allow engine to idle. Oxygen sensor voltage output at idle should fluctuate around.66 volts (on generic scan tool) or 3.3 volts (on Lexus scan tool).
  3. Raise engine speed. Oxygen sensor voltage output should fluctuate around.56 (on generic scan tool) volts or 2.8 volts (on Lexus scan tool) or more. Drive vehicle at least 25 MPH with engine speed at least 1500 RPM. Snap and release throttle. Oxygen sensor voltage output should fluctuate around.76 (on generic scan tool) volts or 3.8 volts (on Lexus scan tool) or less.
  4. If all oxygen sensor voltage outputs are as specified, go to next step. If any oxygen sensor voltage outputs are not as specified, replace oxygen sensor.
  5. Clear trouble codes. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-22507-S32038402032001010300000) under SELF-DIAGNOSTIC SYSTEM. Perform CONFIRMATION TEST. See «DTC P1130»(ref-22507-S09844528022001010300000) and P1150. If DTC P0125 still exists, replace ECM and retest system. If DTC P0125 does not exist, problem is intermittent.

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 engine to idle for one minute. Repeat driving and idle part of test 3 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 engine to idle for one minute. Turn ignition off. Repeat driving and idle part of test. If malfunction exists, MIL will illuminate.
  1. Check for open or short circuit in wiring harness between ECM and suspect oxygen sensor. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. Repair as necessary. If wiring harness is okay, go to next step.
  2. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) 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 (fluctuates around.55 volt or less, +20 percent trim) or rich condition (fluctuates around.4 volt or more, -20 percent trim), see «DTC P0171 OR P0172: SYSTEM TOO LEAN OR TOO RICH (FUEL TRIM)»(ref-22507-S22843366042001010300000) circuit test.
  3. If scan tool indicates a condition other than those indicated instep 2), operate engine at 2500 RPM for 90 seconds. Monitor oxygen sensor voltage. If voltage constantly fluctuates from less than 0.4 volt to more than 5.5 volts, perform CONFIRMATION TEST. If voltage does not fluctuate as specified, replace sensor and retest.

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

  1. Access ECM harness connectors behind glove box. Turn ignition on. Using voltmeter, backprobe ECM harness connector. If DTC P0135 is set, measure voltage between ground and terminal No. 3 (Blue/Black wire) at ECM E8 connector. If DTC P0141 is set, measure voltage between ground and terminal No. 9 (Pink/Black wire) at ECM E10 connector. If DTC P0155 is set, measure voltage between ground and terminal No. 4 (Yellow/Red wire) at ECM E8 connector.
  2. If voltage is 9-14 volts, replace ECM and retest system. If voltage is not 9-14 volts, turn ignition off. Disconnect suspect 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-22507-S40148899102001010300000) table. IDENTIFYING OXYGEN SENSOR HEATER TERMINALS Application Terminal No. 1 Terminal No. 2 Bank 1, Sensor 1 Blue/Black Wire Black/Yellow Wire Bank 1, Sensor 2 Pink/Black Wire Black/Yellow Wire Bank 2, Sensor 1 Yellow/Red Wire Black/Yellow Wire
  3. With sensor temperature at 68°F (20°C), resistance should be 11-16 ohms. If resistance is as specified, check circuits between EFI main relay, oxygen sensor and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. Repair as necessary. If resistance is not as specified, replace suspect oxygen sensor and retest system.
  1. Retrieve trouble codes. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22507-S14440867492001010300000) under SELF-DIAGNOSTIC SYSTEM. If any other codes are displayed other than DTC P0136, diagnose and repair those codes first. If only DTC P0136 is displayed, check for open or short circuit in wiring harness between ECM and oxygen sensor. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) 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. Using scan tool, monitor oxygen sensor output voltage. Raise engine speed to 4000 RPM for 3 minutes. Voltage should fluctuate from.4 volt or less to.5 volt (except California vehicles) or.6 volt (California vehicles), or more.
  3. If voltage responds correctly, check wiring harness connections. Problem may be intermittent. If voltage does not respond correctly, replace oxygen sensor and retest system.
  1. 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.
  2. If scan tool indicates a lean condition (voltage fluctuates around.55 volt or less, and short-term will fluctuate around 20 percent trim) or rich condition (voltage fluctuates around.4 volt or more, and short-term will fluctuate around -20 percent trim), go to next step. If results are other than specified, see «DTC P0130 & P0150»(ref-22507-S25833657392001010300000) HEATED OXYGEN SENSOR CIRCUIT (BANK NO. 1, SENSOR NO. 1) & (BANK NO. 2, SENSOR NO. 1) (EXCEPT CALIFORNIA MODELS) circuit test.
  3. 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.
  4. If all injectors are okay, check Mass Airflow (MAF) sensor and Engine Coolant Temperature (ECT) sensor. See «SYSTEM/COMPONENT TESTS»(ref-22514) article. Replace as necessary. If both components are okay, check primary and secondary ignition systems. See IGNITION CHECKS in «BASIC TESTING»(ref-22506) article. Repair as necessary. If ignition systems are okay, replace ECM and retest system.
  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. Raise engine speed to 1000 RPM for 3 minutes or more. Raise engine speed to 2000 RPM for 1.5 minutes or more. Raise engine speed to 3000 RPM for 1 minute or more. Check for any DTCs and freeze frame data. Turn ignition off for 5 seconds.
  1. Check for misfire during engine warm up only. Check for use of improper fuel. Check proper connector connections. Repair as necessary. 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.
  2. Turn ignition off. Access ECM harness connectors behind glove box. Turn ignition on. Using voltmeter, backprobe ECM connector. Measure voltage between ground and injector terminals at ECM E7 and E8 connectors. See «IDENTIFYING INJECTOR TERMINALS»(ref-22507-S40665531862001010300000) table. If voltage is 9-14 volts for each circuit, go to step 4). If voltage is not 9-14 volts, go to next step. IDENTIFYING INJECTOR TERMINALS Injector No. (1) Terminal No. Wire Color 1 5 Blue 2 6 Red 3 1 Yellow 4 2 White 5 3 Red/Blue 6 4 Green (1) Terminals are located in ECM E7 and E8 connector.
  3. Disconnect injector connector of misfiring cylinder. Using ohmmeter, measure resistance between injector terminals. With injector temperature at 68°F (20°C), if resistance is about 13.4-14.2 ohms, check for open or short circuit in wiring harness between ECM and suspect injector. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. Repair as necessary. If resistance is not about 13.4-14.2 ohms, replace injector.
  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 as necessary.
  5. If all injectors are okay, check EGR system. See «SYSTEM/COMPONENT TESTS»(ref-22514) article. Repair as necessary. If EGR system is okay, check MAF sensor and ECT sensor. See «SYSTEM/COMPONENT TESTS»(ref-22514) article. Replace as necessary. If both components are okay, check engine compression, valve clearance and valve timing. See «BASIC TESTING»(ref-22506) article. Repair as necessary.
  1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) Disconnect EC1 connector. EC1 connector is a wire-to-wire connector located in engine compartment, near idle air control valve. Connector is a Dark Gray 4-pin connector.
  2. Connect a fused jumper wire between terminal No. 1 of male connector to terminal No. 2 of female connector. Connect another fused jumper wire between terminal No. 2 of male connector to terminal No. 1 of female connector. (Scheme 8) Turn ignition on. Turn scan tool on. Clear trouble codes. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-22507-S32038402032001010300000) under SELF-DIAGNOSTIC SYSTEM. Start and warm engine to normal operating temperature.
  3. Snap accelerate engine 3 times to 4000 RPM. Retrieve trouble codes. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22507-S14440867492001010300000) under SELF-DIAGNOSTIC SYSTEM. If same code is repeated as before, go to next step. If code has changed, go to step 5).
  4. Check for open or short circuit(s) between EC1 connector and ECM harness connector. Repair as necessary. If circuits are okay, replace ECM and retest system.
  5. Check for open or short circuit(s) between EC1 connector and suspect knock sensor. If DTC P0325 has changed to DTC P0330, check knock sensor circuit on right bank. If DTC P0330 changed to DTC P0325, check knock sensor circuit on left bank. Repair as necessary. If harness is okay, replace knock sensor.

Scheme 8

Scheme 8
Scheme 8
  1. Disconnect CKP sensor harness connector. Using ohmmeter, measure resistance between sensor connector terminals. Resistance should be 1630-2740 ohms at 14-122°F (-10-50°C) or 2065-3225 ohms at 122-212°F (50-100°C).
  2. Replace sensor as necessary. If sensor is okay, check for open or short circuit in wiring harness between ECM and CKP sensor. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. Repair as necessary. If wiring harness is okay, remove and inspect sensor. Also, inspect signal plate. Replace as necessary. If both components are okay, replace ECM and retest system.
  1. Disconnect CKP sensor harness connector. Using ohmmeter, measure resistance between sensor 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).
  2. Replace sensor as necessary. If sensor is okay, check for open or short circuit in wiring harness between ECM and CMP sensor. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. Repair as necessary. If wiring harness is okay, remove and inspect sensor. Also, inspect signal plate. Replace as necessary. If both components are okay, replace ECM and retest system.
  1. Connect 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. Operate vehicle at 43-56 MPH for 3 minutes or more. Stop vehicle, and allow it to idle for about 2 minutes. Turn ignition off.
  2. Start engine and allow it to idle. Operate vehicle at 43-56 MPH for 3 minutes or more. Stop vehicle and allow it to idle for about 2 minutes.
  3. Check READINESS TESTS mode on scan tool. If COMPL is displayed on scan tool and MIL is not illuminated, system is normal. If INCMPL is displayed and MIL is not illuminated, repeat driving and idle steps of test drive procedure several times.

Diagnosis & Repair (Using Lexus Scan Tool)

  1. Connect Lexus scan tool to DLC No. 3. (Scheme 5) Start and warm engine to normal operating temperature. Read EGR gas temperature. Temperature should be 41-302°F (5-150°C) (not immediately after driving). If temperature is as specified, go to step 7). If temperature is not as specified, go to next step.
  2. Disconnect EGR temperature sensor harness connector. Connector is located underneath throttle body. Connect fused jumper wire between harness connector terminals. EGR gas temperature displayed should be 318.7°F (159.3°C). If temperature displayed is not as specified, go to next step. If temperature displayed is as specified, check sensor connectors and terminals. Repair as necessary. If connectors are okay, replace sensor and retest system.
  3. Remove fused jumper wire. Turn ignition off. Access ECM behind glove box. Backprobing, connect fused jumper wire between ECM E8 harness connector terminals No. 13 (Gray/Yellow wire) and No. 18 (Brown wire). (Scheme 7) Turn ignition on. EGR gas temperature displayed should be 318.7°F (159.3°C).
  4. If temperature displayed is not as specified, replace ECM and retest system. If temperature displayed is as specified, repair open in circuit(s) between ECM E8 connector and EGR temperature sensor.
  5. Disconnect ECM E8 connector. Turn ignition on. EGR gas temperature displayed should be 37.6°F (3.1°C).
  6. If temperature displayed is not as specified, replace ECM and retest system. If temperature displayed is as specified, repair short in circuit(s) between ECM E8 connector and EGR temperature sensor.
  7. Check vacuum hoses. Repair as necessary. If all hoses are okay, go to next step.
  8. Using scan tool, select ACTIVE TEST mode. Using scan tool, turn EGR VSV valve on. EGR VSV is located near air intake chamber assembly. Apply compressed air to port "E". Air should flow from port "F". (Scheme 9) Using scan tool, turn EGR VSV valve off. Apply compressed air to port "E". Air should flow from port "G". If valve operates correctly, go to step 12). If valve does not operate correctly, go to next step.
  9. Remove EGR VSV. Using ohmmeter, measure resistance between valve terminals. Resistance should be 27-33 ohms at 68°F (20°C). 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 EGR VSV.
  10. Apply compressed air to port "E" of EGR VSV. Air should flow from port "G". Using fused jumper wires, apply battery voltage and ground to EGR VSV terminals. Again, apply compressed air to port "E". Air should flow from port "F". Replace EGR VSV as necessary.
  11. If valve meets all specifications, check for an open in wiring harness and connectors between engine compartment junction block and ECM E7 connector. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. Repair as necessary.
  12. Disconnect vacuum hose from EGR valve. Start engine. Apply vacuum to EGR valve. If engine runs rough or stalls, go to next step. If engine does not stall or run rough, check EGR valve intake and exhaust passages. If passages are clean, replace EGR valve and retest system.
  13. Check EGR Vacuum Control Valve (VCV). See «SYSTEM/COMPONENT TESTS»(ref-22514) article. Replace VCV as necessary. If VCV is okay, replace ECM and retest system.

Scheme 9

Scheme 9
Scheme 9

Diagnosis & Repair (Using OBD-II Scan Tool)

  1. Disconnect EGR temperature sensor. Connector is located near throttle body. Using ohmmeter, measure resistance between sensor terminals. If resistance is 2500-600,000 ohms (not immediately after driving), go to next step. If resistance is not 2500-600,000 ohms, replace EGR temperature sensor.
  2. Check for an open or short in wiring harness between EGR temperature sensor and ECM E8 connector. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. Repair as necessary. If wiring is okay, go to next step.
  3. Check all EGR system vacuum hoses. Replace hoses as necessary and retest system. If vacuum hoses are okay, access ECM behind glove box. Ensure ignition is off. Disconnect ECM E7 harness connector. Turn ignition on. Connect a fused jumper wire between ground and terminal No. 18 (Yellow/Green wire) at ECM E7 connector.
  4. Apply compressed air to EGR VSV port "E". (Scheme 9) With fused jumper wire connected to ground, air should flow from port "F". With fused jumper wire disconnected, air should flow from port "G". If EGR VSV operates as specified, go to step 8). If EGR VSV does not operate as specified, go to next step.
  5. Remove EGR VSV. Using ohmmeter, measure resistance between EGR VSV terminals. Resistance should be 27-33 ohms at 68°F (20°C). 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 EGR VSV.
  6. Apply compressed air to port "E" of EGR VSV. Air should flow from port "G". Using fused jumper wires, apply battery voltage and ground to EGR VSV terminals. Again, apply compressed air to port "E". Air should flow from port "F". Replace EGR VSV as necessary.
  7. If valve meets all specifications, check for an open in wiring harness and connectors between engine compartment junction block and ECM E7 connector. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. Repair as necessary.
  8. Disconnect vacuum hose from EGR valve. Start engine. Apply vacuum to EGR valve. If engine runs rough or stalls, go to next step. If engine does not stall or run rough, check EGR valve intake and exhaust passages. If passages are clean, replace EGR valve and retest system.
  9. Check EGR Vacuum Control Valve (VCV). See «SYSTEM/COMPONENT TESTS»(ref-22514) article. Replace VCV as necessary. If VCV is okay, replace ECM and retest system.
  1. Check all EGR system vacuum hoses. Replace hoses as necessary and retest system. If vacuum hoses are okay, check EGR VSV. EGR VSV is located near air intake chamber assembly. Connect Lexus scan tool to DLC No. 3. (Scheme 5) Using scan tool, select ACTIVE TEST mode and go to next step.
  2. Using scan tool, turn EGR VSV valve on. Apply compressed air to port "E". Air should flow from port "F". (Scheme 9) Using scan tool, turn EGR VSV valve off. Apply compressed air to port "E". Air should flow from port "G". If valve operates correctly, go to step 6). If valve does not operate correctly, go to next step.
  3. Remove EGR VSV. Using ohmmeter, measure resistance between valve terminals. Resistance should be 27-33 ohms at 68°F (20°C). 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 EGR VSV.
  4. Apply compressed air to port "E" of EGR VSV. Air should flow from port "G". Using fused jumper wires, apply battery voltage and ground to EGR VSV terminals. Again, apply compressed air to port "E". Air should flow from port "F". Replace EGR VSV as necessary.
  5. If valve meets all specifications, check for an short in Yellow/Green wire between ECM E7 connector and EGR VSV. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. Repair as necessary.
  6. Disconnect vacuum hose from EGR valve. Start engine. Apply vacuum to EGR valve. If engine runs rough or stalls, go to next step. If engine does not stall or run rough, check EGR valve intake and exhaust passages. If passages are clean, replace EGR valve and retest system.
  7. Check EGR valve position sensor. See «DTC P1410: EGR VALVE POSITION SENSOR CIRCUIT MALFUNCTION»(ref-22507-S42715534402001010300000). If EGR valve position sensor is okay, replace ECM and retest system.
  1. Check all EGR system vacuum hoses. Replace hoses as necessary and retest system. If vacuum hoses are okay, access ECM behind glove box. Ensure ignition is off. Disconnect ECM E7 harness connector. Turn ignition on. Connect a fused jumper wire between ground and terminal No. 18 (Yellow/Green wire) at ECM E7 connector.
  2. Apply compressed air to EGR VSV port "E". (Scheme 9) With fused jumper wire connected to ground, air should flow from port "F". With fused jumper wire disconnected, air should flow from port "G". If EGR VSV operates as specified, go to step 6). If EGR VSV does not operate as specified, go to next step.
  3. Remove EGR VSV. Using ohmmeter, measure resistance between valve terminals. Resistance should be 27-33 ohms at 68°F (20°C). 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 EGR VSV.
  4. Apply compressed air to port "E" of EGR VSV. Air should flow from port "G". Using fused jumper wires, apply battery voltage and ground to EGR VSV terminals. Again, apply compressed air to port "E". Air should flow from port "F". Replace EGR VSV as necessary.
  5. If valve meets all specifications, check for an open in wiring harness and connectors between engine compartment junction block and ECM E7 connector. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. Repair as necessary.
  6. Disconnect vacuum hose from EGR valve. Start engine. Apply vacuum to EGR valve. If engine runs rough or stalls, go to next step. If engine does not stall or run rough, check EGR valve intake and exhaust passages. If passages are clean, replace EGR valve and retest system.
  7. Check EGR Vacuum Control Valve (VCV). See «SYSTEM/COMPONENT TESTS»(ref-22514) article. Replace VCV as necessary. If VCV is okay, replace ECM and retest system.

The ECM compares waveform of oxygen sensor located in front of catalytic converter with the waveform of oxygen sensor located behind converter to determine if converter performance has deteriorated. If converter is functioning properly, waveform of oxygen sensor after converter will switch back and forth between rich and lean much more slowly than waveform of oxygen sensor in front of converter.

DTC P0420 is set if after vehicle has warmed up waveforms of heated oxygen sensors (bank 1 sensor 1 and bank 1 sensor 2) have same amplitude, while vehicle and engine speeds are held at a steady rate. Possible causes are

  1. Catalytic Converter
  2. Open Or Short Circuit In Oxygen Sensor Circuit
  3. Oxygen Sensor

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. Raise engine speed to 2500-3000 RPM for 3 minutes. Using Lexus scan tool, ensure heated oxygen sensors (bank 1 sensor 1 and bank 1 sensor 2) feedback to ECM fluctuates around.5 volts.

  1. Retrieve trouble codes. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22507-S14440867492001010300000) under SELF-DIAGNOSTIC SYSTEM. If other codes are displayed, diagnose and repair those codes first and retest system.
  2. If only DTC P0420 is displayed, check bank one and 2 heated oxygen sensor one operation. See «SYSTEM/COMPONENT TESTS»(ref-22514) article. If heated oxygen sensors are okay, check bank one heated oxygen sensor 2 operation. If oxygen sensor is okay, replace catalytic converter.

The ECM compares waveform of oxygen sensor located in front of catalytic converter with the waveform of oxygen sensor located behind converter to determine if converter performance has deteriorated. If converter is functioning properly, waveform of oxygen sensor after converter will switch back and forth between rich and lean much more slowly than waveform of oxygen sensor in front of converter.

DTC P0420 is set if after vehicle has warmed up waveforms of heated oxygen sensors (bank 1 and bank 2) have same amplitude, while vehicle and engine speeds are held at a steady rate. Possible causes are

  1. Catalytic Converter
  2. Open Or Short Circuit In Oxygen Sensor Circuit
  3. Oxygen Sensor

Connect 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. Raise engine speed to 2500-3000 RPM for 3 minutes. Alternate between 3000 and 2000 RPM every 2 seconds. Using scan tool, check waveform of bank 1 and bank 2 heated oxygen sensor.

  1. Retrieve trouble codes. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22507-S14440867492001010300000) under SELF-DIAGNOSTIC SYSTEM. If other codes are displayed, diagnose and repair those codes first and retest system.
  2. If only DTC P0420 is displayed, check bank one and 2 heated oxygen sensor one operation. See «SYSTEM/COMPONENT TESTS»(ref-22514) article. If heated oxygen sensors are okay, check bank one heated oxygen sensor 2 operation. If oxygen sensor is okay, replace catalytic converter.
  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 and VSV for vapor pressure sensor, 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 harness connectors behind glove box. Turn ignition on. Backprobing ECM harness connector, measure voltage between terminals No. 2 (Yellow wire) and No. 18 (Brown wire) at ECM E8 connector. (Scheme 7) 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. 17 (Blue/Red wire) and No. 18 (Brown wire) at ECM E8 connector. Disconnect vacuum hose from vapor pressure sensor. Sensor is located next to brake booster. 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 (4-66 kPa) 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 E8 connector. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) 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 EVAP VSV, vapor pressure sensor 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»(ref-22505) article.
  2. Check all EVAP related vacuum hoses 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»(ref-22517) article.
  3. Access ECM harness connectors behind glove box. Turn ignition on. Backprobing ECM harness connector, measure voltage between terminals No. 2 (Yellow wire) and No. 18 (Brown wire) at ECM E8 connector. (Scheme 7) 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 ECM harness connector, measure voltage between terminals No. 17 (Blue/Red wire) and No. 18 (Brown wire) at ECM E8 connector. Disconnect vacuum hose from vapor pressure sensor. Sensor is located next to brake booster. Connect a vacuum pump to sensor. Voltage should be 2.9-3.7 volts without vacuum applied, and.5 volt or less with 1.2-19.7 in. Hg (4-66 kPa) applied. If voltage is as specified, go to step 6). If voltage is not as specified, go to next step.
  5. Check for an open or short in wiring harness between vapor pressure sensor and ECM E8 connector. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. Repair as necessary. If wiring is okay, replace vapor pressure sensor.
  6. Connect 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 engine. Connect a vacuum gauge to disconnected vacuum hose. 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 10). If vacuum is not as specified, go to next step.
  7. Check for correct routing, looseness, damage and blockage in vacuum hoses between intake manifold and EVAP VSV, and between EVAP VSV and charcoal canister. Repair as necessary. If hoses are okay, go to next step.
  8. Check EVAP VSV. See «SYSTEM/COMPONENT TESTS»(ref-22514) 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.
  9. Check for an open or short in wiring harness between EFI main relay, EVAP VSV and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. Repair as necessary. If wiring is okay, replace ECM and retest system.
  10. Disconnect vapor pressure sensor VSV. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 5)Turn ignition on. Select ACTIVE TEST mode on scan tool. Using scan tool, turn vapor pressure sensor VSV on. Apply compressed air to port "E" of vapor pressure sensor VSV. Air should flow from port "F". (Scheme 9) Using scan tool, turn vapor pressure sensor VSV off. Air should flow from port "G". If valve operates correctly, go to step 13). If valve does not operate correctly, go to next step.
  11. Check vapor pressure sensor VSV. See «SYSTEM/COMPONENT TESTS»(ref-22514) article. If vapor pressure sensor VSV is not okay, replace vapor pressure sensor VSV and charcoal canister. Also clean vacuum hoses between charcoal canister and vapor pressure sensor VSV, and vapor pressure sensor VSV and vapor pressure sensor. If vapor pressure sensor VSV is okay, go to next step.
  12. Check for an open or short in wiring harness between EFI main relay, vapor pressure sensor VSV and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. Repair as necessary. If wiring is okay, replace ECM and retest system.
  13. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) Select ACTIVE TEST mode on scan tool. Ensure vapor pressure sensor VSV is disconnected. Start engine. Using scan tool, activate EVAP VSV. Backprobing ECM harness connector, measure voltage between terminals No. 17 (Blue/Red wire) at ECM E11 connector and No. 18 (Brown wire) at ECM E8 connector. (Scheme 7) Voltage should be 2 volts or less. If voltage is as specified, go to step 15). If voltage is not as specified, go to next step.
  14. Check vacuum hose between charcoal canister and vapor pressure sensor VSV, and between vapor pressure sensor and vapor pressure sensor VSV. Check hoses for correct installation, looseness and damage. Repair as necessary. If vacuum hoses are okay, go to next step.
  15. Remove fuel tank cap. Ensure vapor pressure sensor VSV connector is disconnected. Select ACTIVE TEST mode on scan tool. Start engine. Using scan tool, switch EVAP VSV on for 5 seconds. Backprobing ECM harness connector, measure voltage between terminals No. 17 (Blue/Red wire) at ECM E11 connector and No. 18 (Brown wire) at ECM E8 connector 5 seconds after switching EVAP VSV from on to off. If voltage is 2.5 volts or less, go to next step. If voltage is more than 2.5 volts, replace charcoal canister.
  16. Check charcoal canister. If charcoal canister is okay, replace ECM and retest system.
  1. Check EVAP VSV, vapor pressure sensor 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 «THEORY/OPERATION»(ref-22505) article.
  2. Check all EVAP related vacuum hoses for blockage, damage, looseness and correct routing. Repair as necessary. If vacuum hoses are okay, go to next step. For proper vacuum hose routing, see «VACUUM DIAGRAMS»(ref-22517) article.
  3. Access ECM harness connectors behind glove box. Turn ignition on. Backprobing ECM harness connector, measure voltage between terminals No. 2 (Yellow wire) and No. 18 (Brown wire) at ECM E8 connector. (Scheme 7) 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 ECM harness connector, measure voltage between terminals No. 17 (Blue/Red wire) at ECM E11 connector and No. 18 (Brown wire) at ECM E8 connector. Disconnect vacuum hose from vapor pressure sensor. Sensor is located next to brake booster. 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 (4-66 kPa) applied, go to step 6). If voltage is not as specified, go to next step.
  5. Check for an open or short in wiring harness between vapor pressure sensor and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. Repair as necessary. If wiring is okay, replace vapor pressure sensor.
  6. Disconnect EVAP VSV vacuum hoses. For EVAP VSV location, see «VACUUM DIAGRAMS»(ref-22517) article. Turn ignition on. Access ECM harness connectors behind glove box. Backprobing, connect fused jumper wire between ground and terminal No. 7 (Light Green wire) at ECM E8 connector. (Scheme 7)
  7. Apply compressed air to EVAP VSV port "E". (Scheme 10) Air should flow from port "F". Remove 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.
  8. Check EVAP VSV operation. See «SYSTEM/COMPONENT TESTS»(ref-22514) article. If EVAP VSV is not okay, replace EVAP VSV and charcoal canister as necessary. Also clean vacuum hose between throttle body and EVAP VSV, and EVAP VSV and charcoal canister. If VSV is okay, go to next step.
  9. Check for an open or short in wiring harness between EFI main relay, EVAP VSV and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. Repair as necessary. If wiring is okay, replace ECM and retest system.
  10. Disconnect vapor pressure sensor VSV vacuum hoses. VSV is mounted on top of EVAP charcoal canister. Access ECM harness connectors behind glove box. Turn ignition on. Backprobing, connect fused jumper wire between ground and terminal No. 9 (White/Red wire) at ECM E11 connector. (Scheme 7) Apply compressed air to VSV port "E". (Scheme 9)
  11. Air should flow from port "F". Disconnect fused jumper wire. Air should flow from port "G". If VSV does not function as specified, go to next step. If VSV functions as specified, check charcoal canister. See «SYSTEM/COMPONENT TESTS»(ref-22514) article. Replace canister as necessary.
  12. Check vapor pressure sensor VSV. See «SYSTEM/COMPONENT TESTS»(ref-22514) article. Replace VSV as necessary. If VSV is okay, go to next step. If vapor pressure sensor VSV is not okay, replace vapor pressure sensor VSV and charcoal canister as necessary. Also clean vacuum hose between charcoal canister and vapor pressure sensor VSV, and vapor pressure sensor VSV and vapor pressure sensor.
  13. Check for an open or short in wiring harness between EFI main relay, vapor pressure sensor VSV and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. Repair as necessary. If wiring is okay, replace ECM and retest system.

Scheme 10

Scheme 10
Scheme 10
  1. Access ECM harness connectors behind glove box. Turn ignition on. Backprobing ECM harness connector, measure voltage between terminals No. 2 (Yellow wire) and No. 18 (Brown wire) at ECM E8 connector. (Scheme 7) 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 ECM harness connector, measure voltage between terminals No. 17 (Blue/Red wire) at ECM E11 connector and No. 18 (Brown wire) at ECM E8 connector. Disconnect vacuum hose from vapor pressure sensor. Sensor is located next to brake booster. 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 (4-66 kPa) 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 between vapor pressure sensor and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. Repair as necessary. If wiring is okay, replace vapor pressure sensor. Retest system.
  1. 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.
  2. Access ECM behind glove box. Turn ignition off. Disconnect ECM E10 connector. (Scheme 7) Using voltmeter, check for continuity between ground and terminal No. 22 (Violet/White wire) at ECM E10 harness connector. If continuity does not exist, go to next step. If continuity exists, locate and repair short to ground in Violet/White wire between ECM E10 connector and instrument cluster.
  3. Turn ignition on. Measure voltage between ground and terminal No. 22 (Violet/White wire) at ECM E10 harness connector. If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, locate and repair open in Violet/White wire between junction connector J17, located behind center of instrument panel and ECM.
  4. Check for open in Violet/White wire between junction block J17 and instrument cluster. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. Repair wiring as necessary and retest system. If wiring is okay, replace ECM and retest system.
  1. If using Lexus Scan Tool, go to next step. If using OBD-II Scan Tool, go to step 3).
  2. Warm engine to operating temperature. Turn accessories and A/C off. Place transmission in Neutral. Connect Lexus scan tool to DLC No. 3 and select ACTIVE TEST MODE. (Scheme 5)Using Lexus scan tool, turn TE1 on and off. Record engine speed 5 seconds before and after TE1 is turned on and off. If engine speed changes more than 100 RPM, go to step 9). If engine speed does not change more than 100 RPM, go to step 4).
  3. Warm engine to operating temperature. Turn accessories and A/C off. Place transmission in Neutral. Connect OBD-II scan tool to DLC No. 3. Connect Jumper Wire (09843-18020) between DLC No. 1 connector terminals No. 8 (Blue/White wire) and No. 3 (Brown wire). DLC No. 1 is located above right side of intake manifold. Connect and disconnect Jumper Wire (09843-18020) several times. Record engine speed 5 seconds before and after wire harness (09843-18020) is connected and disconnected. If engine speed changes more than 100 RPM, go to step 9). If engine speed does not change more than 100 RPM, go to next step.
  4. Access ECM behind glove box. Turn ignition off. Disconnect ECM E7 connector. (Scheme 7) Turn ignition on. Using voltmeter, measure voltage between ground and terminals No. 15 (Yellow/Black wire) and No. 16 (Red/White wire) at ECM E7 connector. If both readings are 9-14 volts, go to step 7). If any reading is not 9-14 volts, go to next step.
  5. Disconnect IAC valve connector. Measure resistance between Black/Yellow wire terminal and Red/White and Yellow/Black wire terminals at IAC valve. Resistance should be 17-24.5 ohms at 14-122°F (-10-50°C) or 21.5-28.5 ohms at 122-212°F (50-100°C). If both readings are as specified, check for open or short circuit in connectors or wiring harness between engine compartment junction block and IAC valve, or between IAC and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. If any reading is not as specified, replace IAC valve.
  6. Check IAC valve resistance. See IDLE CONTROL SYSTEM in «SYSTEM/COMPONENT TESTS»(ref-22514) article. Replace IAC valve as necessary. If IAC valve is okay, check for open or short circuit in connectors or wiring harness between engine compartment junction block and IAC valve, or between IAC and ECM. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. If any reading is not as specified, replace IAC valve.
  7. Check IAC valve operation. See IDLE CONTROL SYSTEM in «SYSTEM/COMPONENT TESTS»(ref-22514) article. Replace IAC valve as necessary. If IAC valve is okay, go to next step.
  8. Check IAC valve and IAC passage for blockage. If IAC valve and passage are not clear, repair or replace IAC valve as necessary. If IAC valve and passage are clear, replace ECM and retest system.
  9. Check A/C signal circuit. See «1998 A/C-HEATER SYSTEM»(ref-36654) article in the AIR CONDITIONING & HEAT section. Replace as necessary. If A/C signal circuit is okay, check air induction system.
  1. If using Lexus scan tool, go to next step. If not using Lexus scan tool, go to step 3).
  2. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) Switch scan tool to CHECK mode. Ensure all accessories are off. Start engine and allow engine to reach normal operating temperature. Drive vehicle at 38-75 MPH with engine speed at 1400-3200 RPM for 3-5 minutes. Confirm DTC P1130 & P1150 exist.
  3. Ensure all accessories are off. Start engine and allow engine to reach normal operating temperature. Drive vehicle at 38-75 MPH with engine speed at 1400-3200 RPM for 3-5 minutes. Turn engine off. Repeat this step. Confirm DTC P1130 & P1150 exist.
  1. Retrieve trouble codes. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22507-S14440867492001010300000) under SELF-DIAGNOSTIC SYSTEM. If only DTC P1130 or P1150 is displayed, go to next step. If other codes are displayed, diagnose and repair those codes first and retest system.
  2. Using an ohmmeter, measure resistance between oxygen sensor connector terminals No. 1 (Black/Red wire) and No. 2 (Black wire) of bank No. 1 oxygen sensor No. 1. Also measure resistance between oxygen sensor connector terminals No. 1 (Black/White wire) and No. 2 (Black wire) of bank No. 2 oxygen sensor No. 1. Resistance should be 11-16 ohms at 68°F (20°F). If resistance is not as specified, replace suspect oxygen sensor. If resistance is as specified, go to next step.
  3. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) Start engine and run it at 2500 RPM for 90 seconds. Using scan tool, monitor bank No. 1 and No. 2 oxygen sensors No. 1. Allow engine to idle. Oxygen sensor voltage output at idle should fluctuate around.66 volts (on generic scan tool) or 3.3 volts (on Lexus scan tool).
  4. Raise engine speed. Oxygen sensor voltage output should fluctuate around.56 (on generic scan tool) volts or 2.8 volts (on Lexus scan tool) or less. Drive vehicle at least 25 MPH with engine speed at least 1500 RPM. Snap and release throttle. Oxygen sensor voltage output should fluctuate around.76 (on generic scan tool) volts or 3.8 volts (on Lexus scan tool) or more.
  5. If any oxygen sensor voltage outputs are as specified, go to next step. If any oxygen sensor voltage outputs are not as specified, check for open or short in wiring harness and connectors between ECM and suspect oxygen sensor. Repair wiring as necessary and retest system. If wiring harness and connectors are okay, replace suspect oxygen sensor.
  6. Perform confirmation test. See CONFIRMATION TEST. If DTC P1130 or P1150 is set, replace ECM and retest system. If DTC P1130 or P1150 is not set, problem is intermittent.
  1. Retrieve trouble codes. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22507-S14440867492001010300000) under SELF-DIAGNOSTIC SYSTEM. If only DTC P1133 or P1153 is displayed, go to next step. If other codes are displayed, diagnose and repair those codes first and retest system.
  2. Using an ohmmeter, measure resistance between oxygen sensor connector terminals No. 1 (Black/Red wire) and No. 2 (Black wire) of bank No. 1 oxygen sensor No. 1. Also measure resistance between oxygen sensor connector terminals No. 1 (Black/White wire) and No. 2 (Black wire) of bank No. 2 oxygen sensor No. 1. Resistance should be 11-16 ohms at 68°F (20°F). If resistance is not as specified, replace suspect oxygen sensor. If resistance is as specified, go to next step.
  3. If using Lexus scan tool, go to next step. If not using Lexus scan tool, go to step 5).
  4. Connect Lexus scan tool to Data Link Connector (DLC) No. 3. (Scheme 5) Switch scan tool to CHECK mode. Ensure all accessories are off. Start engine and allow engine to reach normal operating temperature. Drive vehicle at 38-75 MPH with engine speed at 1400-3200 RPM for 3-5 minutes. Go to step 6).
  5. Ensure all accessories are off. Start engine and allow engine to reach normal operating temperature. Drive vehicle at 38-75 MPH with engine speed at 1400-3200 RPM for 3-5 minutes. Turn engine off. Repeat this step and go to step 6).
  6. If DTC P1130 or P1150 is set, replace suspect oxygen sensor and retest system. If DTC P1130 or P1150 is not set, problem is intermittent.
  1. Access ECM behind glove box. Turn ignition on. Using voltmeter, backprobing, measure voltage between ground and terminals No. 3 (Black/Red wire) and No. 4 (Black/White wire) at ECM E8 connector. (Scheme 7) If both readings are 9-14 volts, replace ECM and retest system. If any reading is not 9-14 volts, go to next step.
  2. Using an ohmmeter, measure resistance between oxygen sensor connector terminals No. 1 (Black/Red wire) and No. 2 (Black wire) of bank No. 1 oxygen sensor No. 1. Also measure resistance between oxygen sensor connector terminals No. 1 (Black/White wire) and No. 2 (Black wire) of bank No. 2 oxygen sensor No. 1. Resistance should be 11-16 ohms at 68°F (20°F) at both sensors. If resistance is not as specified, replace suspect oxygen sensor. If resistance is as specified, check wiring harness and connectors between EFI main relay, suspect oxygen sensor and ECM.
  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 White/Red wire between terminal No. 25 (White/Red wire) at ECM E7 connector and ignitor. Ignitor is located near left shock tower. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. Repair as necessary. If circuit is okay, go to next step.
  3. Disconnect Black 10-pin ignitor connector. Access ECM behind glove box. Turn ignition on. Backprobing, measure voltage between ground and terminal No. 25 (White/Red wire) at ECM E7 connector. (Scheme 7) If voltage is 4.5-5.5 volts, replace ignitor. If voltage is not 4.5-5.5 volts, replace ECM and retest system.
  4. Check for open or short in Gray wire, Brown/Yellow wire and Light Green/Black wire between ECM E7 connector and ignitor. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. Repair as necessary. If circuits are okay, go to next step.
  5. Access ECM behind glove box. Locate ECM E7 connector. (Scheme 7) Backprobing ECM E7 connector, measure voltage between ground and terminals No. 13 (Light Green/Black wire), No. 12 (Brown/Yellow wire) and No. 11 (Gray wire) at ECM E7 connector while cranking engine. If all readings are.1-4.5 volts, go to next step. If any reading is not.1-4.5 volts, replace ECM and retest system.
  6. Disconnect Black 10-pin ignitor connector. Ignitor is located near left shock tower. Backprobing ECM E7 connector, measure voltage between ground and terminals No. 13 (Light Green/Black wire), No. 12 (Brown/Yellow wire) and No. 11 (Gray wire) at ECM E7 connector while cranking engine. If all readings are.1-4.5 volts, go to next step. If any reading is not.1-4.5 volts, replace ECM and retest system.
  7. Measure voltage between ground and terminal No. 9 (Black/Red wire) at ignitor wiring harness connector. (Scheme 11) Turn ignition switch to ON position and than to START position. If voltage is not 9-14 volts in both positions, go to next step. If voltage is 9-14 volts in both positions, check and repair ignitor power source circuit. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article.
  8. Check for an open or short in wiring harness between ignition switch and ignition coil, and between ignition coil and ignitor. Repair as necessary. If wiring is okay, go to next step.
  9. Check ignition coil. See IGNITION SYSTEM in «SYSTEM/COMPONENT TESTS»(ref-22514) article. Replace coil as necessary. If coil is okay, check EFI main relay. Continuity should exist between EFI main relay terminals No. 1 and 2. Continuity should not exist between EFI main relay terminals No. 3 and 5. If continuity is as specified, go to next step.
  10. Apply battery voltage and ground to EFI main relay terminals No. 1 and 2. (Scheme 12) Continuity should exist between EFI main relay terminals No. 3 and 5. If continuity is not as specified, replace EFI main relay. If continuity is as specified, replace ignitor and retest system.

Scheme 11

Scheme 11
Scheme 11

Scheme 12

Scheme 12
Scheme 12
  1. Disconnect EGR valve vacuum hose. Disconnect EGR valve position sensor connector. Turn ignition on. Measure voltage between ground and Yellow wire at EGR valve position sensor wiring harness connector. If voltage is not 4.5-5.5 volts, go to step 4). If voltage is 4.4-5.5 volts, go to next step.
  2. Measure resistance between terminals No. 1 (Yellow wire) and No. 2 (Brown wire) at EGR valve position sensor. If resistance is 1500-4300 ohms, go to next step. If resistance is not 1500-4300 ohms, replace EGR valve position sensor and retest system.
  3. Connect vacuum pump to EGR valve. Access ECM behind glove box. Backprobing ECM connector, measure voltage between terminals No. 18 (Brown wire) at ECM E8 connector and No. 22 (White/Green wire) at ECM E7 connector. (Scheme 7) With no vacuum applied, voltage should be.4-1.6 volt. With 5.12 in. Hg (17.3 kPa) of vacuum applied, voltage should be 3.2-5.1 volts. If voltage is as specified, replace ECM and retest system. If voltage is not as specified, check for an open or short in wiring harness or connectors between ECM and EGR valve position sensor. Repair as necessary and retest system.
  4. Access ECM behind glove box. Turn ignition on. Backprobing ECM connector, measure voltage between terminals No. 18 (Brown wire) and No. 2 (Yellow wire) at ECM E8 connector. (Scheme 7) If voltage is 4.5-5.5 volts, check for an open or short in wiring harness between ECM E8 connector and EGR valve position sensor. Repair as necessary and retest system. If voltage is 4.5-5.5 volts, replace ECM and retest system.

Retrieve trouble codes. See RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. If only DTC P1411 is displayed, replace EGR valve position sensor and retest system. If other codes are displayed, diagnose and repair those codes first and retest system.

  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 DLC No. 3. (Scheme 5) Turn ignition on. Turn Lexus scan tool on. Read STP signal on Lexus scan tool. STP signal should be on with brake pedal depressed, and should be off with brake pedal released. If STP signal responds as specified, problem is intermittent. If STP signal does not respond as specified, go to step 5).
  4. Access ECM behind glove box. Turn ignition on. Backprobing ECM E11 connector, measure voltage between ground and terminal No. 15 (Green/White wire) at ECM E11 connector. (Scheme 7) With brake pedal depressed, voltage should be 7.5-14 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, problem is intermittent.
  5. Check connector and for short in Green/White wire between ECM E11 connector and stoplight switch. Repair as necessary and retest system. If wiring harness is okay, replace ECM. Retest system.
  1. Access ECM behind glove box. Locate ECM E7 connector. (Scheme 7) Backprobing ECM connector, measure voltage between ground and terminal No. 14 (Black/Yellow wire) at ECM E7 connector. If voltage is not 9-14 volts, go to next step. If voltage is 9-14 volts, replace ECM and retest system.
  2. Remove and inspect EFI fuse (15-amp) from junction block, located in left 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.
  1. If using Lexus scan tool, go to next step. If not using Lexus scan tool, go to step 3).
  2. Connect Lexus scan tool to DLC No. 3. (Scheme 5) Turn ignition on. Turn scan tool on. Using scan tool, read transaxle shift positions while shifting transaxle shift lever through all gear positions. If scan tool display does not indicate correct shifter positions, go to next step. If scan tool display indicates correct shifter positions, Park/Neutral position switch is functioning properly. Problem is internal transaxle. Identify symptom and repair as necessary. See TRANSMISSION SERVICE & REPAIR article.
  3. Access ECM behind glove box. Turn ignition on. Backprobing, measure voltage between ground and ECM E10 connector NSW circuit terminal No. 20 (Black/White wire), "R" circuit terminal No. 2 (Red/Black wire), "2" circuit terminal No. 3 (Blue/White wire), and "L" circuit terminal No. 12 (Yellow wire). (Scheme 7) Shift lever through all gear positions. (Scheme 13) If voltage is not as specified, go to next step. If voltage is as specified, park/neutral position switch is functioning properly. Problem is internal transaxle. Identify symptom and repair as necessary. See TRANSMISSION SERVICE & REPAIR article.
  4. Check park/neutral position switch. See ENGINE SENSORS & SWITCHES in «SYSTEM/COMPONENT TESTS»(ref-22514) article. Replace switch as necessary. If switch is okay, check connector and for short circuit in wiring harness between batter and park/neutral switch. Also check between ECM E10 connector and park/neutral position switch. See appropriate wiring diagram in «SYSTEM WIRING DIAGRAMS»(ref-120548) article. Repair as necessary and retest system. If wiring harness is okay, replace ECM and retest system.

Scheme 13

Scheme 13
Scheme 13

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