Engine Controls - Tests W/codes: Diagnosis Lexus SC I

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 WIRING DIAGRAMS article. See «ECM LOCATION»(ref-22023-S42289781612001010300000) .
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-22023-S17519092232001010300000) .

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 tester. Retrieve codes and record any freeze-frame data. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-22023-S17519092232001010300000) .
3. Clear Trouble Codes Clear codes using scan tester. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-22023-S04919415712001010300000) .
4. 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-22023-S16408327382001010300000) . If no codes are present, proceed to TROUBLE SHOOTING - NO CODES article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.).
7. Verification Procedure After repairs have been completed, clear all diagnostic trouble codes. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-22023-S04919415712001010300000) . 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 tester or On-Board Diagnostic (OBD-II) scan tester that complies with SAE standard J-1978. Lexus scan tester or OBD-II scan tester may be operated in NORMAL mode when retrieving trouble codes. Only Lexus scan tester may be used in CHECK mode when retrieving DTCs.

NORMAL mode is used to retrieve DTCs from Engine Control Module (ECM). CHECK mode is used to check for DTCs when operating vehicle to simulate conditions 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 tester, when ignition is turned from ON to ACC or OFF position or scan tester 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.

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 tester and scan tester manufacturer's instructions. NOTE: If using Lexus Scan Tester, 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.

DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION

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 5) 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 5

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 tester displays UNABLE TO CONNECT TO VEHICLE when scan tester is connected, try scan tester on another vehicle. If scan tester operates on another vehicle, go to next step. If scan tester does not operate on another vehicle, problem is probably with scan tester.
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 WIRING DIAGRAMS article. Repair as necessary. If connector and terminals are okay, go to next step.
3. Check voltage and resistance between ground and specified terminal on DLC No. 3. See «DLC NO»(ref-22023-S41731367982001010300000). 3 VOLTAGE & RESISTANCE SPECIFICATIONS table. (Scheme 6) If voltage and resistance readings are not as specified, check wiring circuit. See appropriate wiring diagram in WIRING DIAGRAMS article.

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

DLC NO. 3 VOLTAGE & RESISTANCE SPECIFICATIONS

Scheme 6

Diagnosis & Repair

1. Remove instrument panel fuse cover. Connect scan tester to Data Link Connector (DLC) No. 3. see scheme 1 Start engine and allow it to idle. Turn on scan tester. Monitor MAF rate. If scan tester 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 harness connector. Turn ignition on with engine off. Using DVOM, measure voltage between ground and terminal No. 1 (Black/Red wire) at MAF sensor 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 ECM.
3. Access ECM behind glove box. Connect Check Harness "A" (SST 09990-01000) to ECM. See TEST PREPARATION under SELF-DIAGNOSTIC SYSTEM. Start engine. Measure voltage between ground and terminal No. 66 (Blue/Yellow wire) at ECM "B" connector. (Scheme 5) 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 circuit in wiring harness between MAF sensor and ECM. If wiring is okay, replace MAF sensor and retest.
5. Access ECM behind glove box. Turn ignition off. Check for continuity between ground and terminal No. 30 (Green/White wire) at ECM "B" connector. On all models, if continuity does not exist, replace ECM and retest. If continuity exists, go to next step.
6. Check for an open in wiring harness between MAF sensor and ECM. Repair as necessary. If wiring is okay, replace MAF sensor.

Scheme 7

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. Remove instrument panel fuse cover. Connect scan tester to Data Link Connector (DLC) No. 3. see scheme 1 Turn ignition on. Turn scan tester on. Monitor IAT sensor temperature. If temperature displayed is same as actual intake air temperature, inspect 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 harness connector. Connect a jumper wire between terminals No. 3 (Yellow/Black wire) and No. 4 (Brown wire) at MAF sensor harness connector. Turn ignition on. Monitor IAT sensor temperature on scan tester.
3. If temperature displayed is 284°F (140°C) or more, replace MAF sensor and retest. If temperature displayed is less than 284°F (140°C), turn ignition off. Remove jumper wire. Access ECM behind glove box. Connect Check Harness "A" (SST 09990-01000) to ECM. See TEST PREPARATION under SELF-DIAGNOSTIC SYSTEM. Connect jumper wire between terminals No. 45 (Yellow/Black wire) and No. 65 (Brown wire) at ECM "B" connector. (Scheme 5)
4. If temperature displayed on scan tester is 284°F (140°C) or more, inspect and repair circuits between MAF harness connector and ECM. If temperature displayed on scan tester is not 284°F (140°C) or more, replace ECM and retest.
5. Turn ignition off. Disconnect MAF sensor harness connector. Turn ignition on. If temperature displayed on scan tester 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 behind glove box. Disconnect "B" connector from ECM. Turn ignition on. If temperature displayed is -40°F (-40°C), inspect and repair circuits between MAF sensor and ECM for short. If temperature displayed by scan tester is not -40°F (-40°C), replace ECM and retest.

1. Remove instrument panel fuse cover. Connect scan tester to Data Link Connector (DLC) No. 3. see scheme 1 Turn ignition on. Turn scan tester on. Monitor ECT sensor temperature. If temperature displayed is same as actual coolant temperature, inspect 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 jumper wire between terminals No. 2 (Green wire) and No. 1 (Brown wire) at ECT sensor harness connector. Turn ignition on. Monitor ECT sensor temperature on scan tester.
3. If temperature displayed is 284°F (140°C) or more, replace ECT sensor and retest. If temperature displayed is less than 284°F (140°C), turn ignition off. Remove jumper wire. Access ECM behind glove box. Connect Check Harness "A" (SST 09990-01000) to ECM. See TEST PREPARATION under SELF-DIAGNOSTIC SYSTEM. Connect jumper wire between terminals No. 44 (Green wire) and No. 65 (Brown wire) at ECM "B" connector. (Scheme 5)
4. If temperature displayed on scan tester is 284°F (140°C) or more, inspect and repair circuits between ECT harness connector and ECM. If temperature displayed on scan tester is not 284°F (140°C) or more, replace ECM and retest.
5. Turn ignition off. Disconnect ECT sensor harness connector. Turn ignition on. If temperature displayed on scan tester is -40°F (-40°C), replace ECT sensor and retest. If temperature displayed is not -40°F (-40°C), turn ignition off.
6. Access ECM behind glove box. Disconnect "B" connector from ECM. Turn ignition on. If temperature displayed is -40°F (-40°C), inspect and repair circuits between ECT sensor and ECM for short. If temperature displayed by scan tester is not -40°F (-40°C), replace ECM and retest.

If only DTC P0116 is displayed, replace ECT sensor and retest. If other codes are displayed, diagnose and repair those codes first and retest.

1. Remove instrument panel fuse cover. Connect scan tester to Data Link Connector (DLC) No. 3. see scheme 1 Turn ignition on. Turn scan tester on. 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 70. If percentages are within specification, inspect 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 DVOM, measure voltage between ground and Blue/Red 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 (Brown wire) and No. 4 (Blue/Red wire) at TP sensor component connector. Resistance should be 3100-7200 ohms. Measure resistance between terminals No. 1 (Brown wire) and No. 3 (Yellow wire). Resistance should be 340-6300 ohms with throttle fully closed, and 2400-11,200 ohms with throttle fully open. If any reading is 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. Connect Check Harness "A" (SST 09990-01000) to ECM. See TEST PREPARATION under SELF-DIAGNOSTIC SYSTEM. Turn ignition on. Measure voltage between terminals No. 43 (Yellow wire.) and No. 65 (Brown wire) at ECM "B" connector. (Scheme 5) Voltage should be.3-.8 volt with throttle fully closed, and 3.2.-4.9 volts with throttle fully open (WOT). If voltages are as specified, replace ECM and retest. If voltages are not as specified, locate and repair open or short circuit in wiring harness between ECM and TP sensor.
5. Access ECM harness connectors behind glove box. Connect Check Harness "A" (SST 09990-01000) to ECM. See TEST PREPARATION under SELF-DIAGNOSTIC SYSTEM. Turn ignition on. Measure voltage between terminals No. 41 (Blue/Red wire) and No. 65 (Brown wire) at ECM "B" connector. If voltage is 4.5-5.5 volts, locate and repair open in Blue/Red wire between TP sensor and ECM. If voltage is not 4.5-5.5 volts, replace ECM and retest.

If only DTC P0121 is displayed, replace TP sensor and retest. If other codes are displayed, diagnose and repair those codes first and retest.

1. Remove instrument panel fuse cover. Connect scan tester to Data Link Connector (DLC) No. 3. see scheme 1 Start engine and warm to normal operating temperature. Turn scan tester on. Monitor each oxygen sensor. Snap accelerate engine 3 times. 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, inspect circuits between ECM and suspect sensor for open or short circuits. Repair as necessary. If circuits are okay, replace oxygen sensor and retest.

Test Drive Confirmation

1. Remove instrument panel fuse cover. Connect scan tester to Data Link Connector (DLC) No. 3. see scheme 1 If using Lexus scan tester, switch to CHECK mode. 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. If malfunction exists, MIL will illuminate.
2. If using OBD-II scan tester, 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 vehicle off. Repeat driving and idle part of test. If malfunction exists, MIL will illuminate.

1. Inspect circuits between ECM and oxygen sensor for opens or shorts. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If all circuits are okay, connect scan tester. see scheme 1
2. Start engine and warm to normal operating temperature. Monitor heated oxygen sensor output voltage and short-term fuel trim. If scan tester indicates a lean condition (.55 volt or less, +20 trim) or rich condition (.4 volt or more, -20 trim), see «DTC P0171»(ref-22023-S11086120812001010300000) - SYSTEM TOO LEAN (FUEL TRIM), DTC P0172 - SYSTEM TOO RICH (FUEL TRIM) circuit test.
3. If scan tester indicates other than in step 2), operate engine at 2500 RPM for 90 seconds. Monitor oxygen sensor voltage. If voltage constantly fluctuates in wide range (.4-.6 volt), repeat TEST DRIVE CONFIRMATION. If voltage does not fluctuate, or stays in narrow range, replace sensor and retest.

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 harness connectors behind glove box. Connect Check Harness "A" (SST 09990-01000) to ECM. See TEST PREPARATION under SELF-DIAGNOSTIC SYSTEM. Turn ignition on. If DTC P0135 is set, measure voltage between ground and terminal No. 73 (Yellow/Blue wire) at ECM "B" connector. If DTC P0141 is set, measure voltage between ground and terminal No. 72 (Yellow/Red wire) at ECM "B" connector. If DTC P0155 is set, measure voltage between ground and terminal No. 36 (Brown/White wire) at ECM "A" connector.
2. If voltage is 9-14 volts, replace ECM and retest. If voltage is not 9-14 volts, 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-22023-S10493224482001010300000) table. IDENTIFYING OXYGEN SENSOR HEATER TERMINALS Application Terminal No. 1 Terminal No. 2 Bank 1, Sensor 1 Brown Wire Black/Red Wire Bank 1, Sensor 2 Yellow/Red Wire Black/Red Wire Bank 2, Sensor 1 Brown/White Wire Black/Red Wire
3. With sensor temperature at 68°F (20°C), resistance should be 11.7-14.3 ohms. If resistance is as specified, inspect circuits between main relay, sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If resistance is not as specified, replace sensor and retest.

1. If any other codes are displayed other than DTC P0136, diagnose and repair those codes first. If only DTC P0136 is displayed, inspect circuits between ECM and oxygen sensor for opens or shorts. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary.
2. If all circuits are okay, remove instrument panel fuse cover. Connect scan tester to Data Link Connector (DLC) No. 3. see scheme 1 Start and warm engine to normal operating temperature. 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 or more.
3. If voltage responds correctly, inspect harness connections. Problem may be intermittent. If voltage does not respond correctly, replace oxygen sensor and retest.

See DTC P0135 - HEATED OXYGEN SENSOR CIRCUIT (BANK NO. 1, SENSOR NO. 1), DTC P0141 -HEATED OXYGEN SENSOR CIRCUIT (BANK NO. 1, SENSOR NO. 2), DTC P0155 - HEATED OXYGEN SENSOR CIRCUIT (BANK NO. 2, SENSOR NO. 1) circuit test.

See DTC P0130 - HEATED OXYGEN SENSOR FAULT (BANK NO. 1, SENSOR NO. 1), DTC P0150 - HEATED OXYGEN SENSOR FAULT (BANK NO. 2, SENSOR NO. 1) circuit test.

See DTC P0133 - HEATED OXYGEN SENSOR (BANK NO. 1, SENSOR NO. 1) CIRCUIT SLOW RESPONSE, DTC P0153 - HEATED OXYGEN SENSOR (BANK NO. 2, SENSOR NO. 1) CIRCUIT SLOW RESPONSE circuit test.

See DTC P0135 - HEATED OXYGEN SENSOR CIRCUIT (BANK NO. 1, SENSOR NO. 1), DTC P0141 - HEATED OXYGEN SENSOR CIRCUIT (BANK NO. 1, SENSOR NO. 2), DTC P0155 - HEATED OXYGEN SENSOR CIRCUIT (BANK NO. 2, SENSOR NO. 1) circuit test.

1. Inspect all air induction components. Repair as necessary. If air induction components are okay, connect scan tool. see scheme 1 Start engine and warm to normal operating temperature. Monitor heated oxygen sensor output voltage and short-term fuel trim.
2. If scan tester indicates a lean condition (.55 volt or less, +20 trim) or rich condition (.4 volt or more, -20 trim), go to next step. If results are other than specified, see «DTC P0130»(ref-22023-S30040550732001010300000) - HEATED OXYGEN SENSOR FAULT (BANK NO. 1, SENSOR NO. 1), DTC P0150 - HEATED OXYGEN SENSOR FAULT (BANK NO. 2, SENSOR NO. 1) circuit test.
3. Inspect fuel pressure. See BASIC DIAGNOSTIC PROCEDURES article. Repair as necessary. If fuel pressure is okay, inspect fuel injectors. See SYSTEM & COMPONENT TESTING article. Replace injectors as necessary.
4. If all injectors are okay, inspect Mass Airflow (MAF) sensor and Engine Coolant Temperature (ECT) sensor. See SYSTEM & COMPONENT TESTING article. Replace as necessary. If both components are okay, inspect ignition system. See IGNITION CHECKS in BASIC DIAGNOSTIC PROCEDURES article. Repair as necessary. If ignition system is okay, replace ECM and retest.

Circuit Description

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 is set when misfiring of random cylinders is detected during any particular 200 or 1000 revolutions. Possible causes are

1. Ignition system.
2. Injector(s).
3. Fuel pressure.
4. EGR system.
5. Engine compression.
6. Valve clearance.
7. Valve timing.
8. Mass Airflow (MAF) sensor.
9. Engine Coolant Temperature (ECT) sensor.

1. Inspect spark plugs and ignition system. See BASIC DIAGNOSTIC PROCEDURES article. Repair as necessary. If ignition system is okay, ensure ignition is off.
2. Access ECM harness connectors behind glove box. Connect Check Harness "A" (SST 09990-01000) to ECM. See TEST PREPARATION under SELF-DIAGNOSTIC SYSTEM. Turn ignition on. Measure voltage between ground and injector terminals at ECM "B" connector. See «IDENTIFYING INJECTOR TERMINALS»(ref-22023-S17348362242001010300000) 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 20 Yellow 2 19 Black/Yellow 3 18 Brown 4 17 Black/Red 5 16 White 6 15 Blue/Red (1) Terminals are located in ECM "B" connector.
3. Disconnect injector of misfiring cylinder. Using ohmmeter, measure resistance between injector terminals. With injector temperature at 68°F (20°C), if resistance is 13.4-14.2 ohms, inspect circuits between ECM and injector for open or short circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If resistance is not 13.4-14.2 ohms, replace injector.
4. Check fuel pressure. See BASIC DIAGNOSTIC PROCEDURES article. Repair as necessary. If fuel pressure is okay, inspect fuel injectors. See SYSTEM & COMPONENT TESTING article. Replace as necessary.
5. If all injectors are okay, inspect EGR system. See SYSTEM & COMPONENT TESTING article. Repair as necessary. If EGR system is okay, inspect MAF sensor and ECT sensor. See SYSTEM & COMPONENT TESTING article. Replace as necessary. If both components are okay, check engine compression, valve clearance and valve timing. See BASIC DIAGNOSTIC PROCEDURES article. Repair as necessary.

See DTC P0300 - RANDOM MISFIRE DETECTED.

See DTC P0300 - RANDOM MISFIRE DETECTED.

1. Access ECM harness connectors behind glove box. Connect Check Harness "A" (SST 09990-01000) to ECM connectors, leaving ECM disconnected. See TEST PREPARATION under SELF-DIAGNOSTIC SYSTEM. Turn ignition on. Measure resistance between ground and terminals No. 49 (White wire) and No. 50 (White wire) at ECM "B" connector. If both readings are infinite, go to step 3). If any reading is not infinite, go to next step.
2. Disconnect knock sensor connector. Using an ohmmeter, check for continuity between 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 circuit in wiring harness between knock sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS 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. Disconnect distributor 4-pin connector. Using ohmmeter, measure resistance between terminals No. 1 (Blue wire) and No. 4 (Black). Resistance should be 155-250 ohms with engine temperature at less than 122°F (50°C), or 190-290 ohms with engine temperature at more than 122°F (50°C). If resistance is not as specified, replace distributor. If resistance is as specified, go to next step.
2. Inspect NE signal circuit between ECM and distributor for open or short circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If circuit is okay, go to next step.
3. Remove distributor cap. Measure air gap of pick-up coils G1, G2 and NE. If air gap is .008-.020" (.20-.50 mm), replace ECM and retest. If air gap is not within specification, replace distributor.

1. Disconnect distributor 4-pin connector. Measure resistance between terminal No. 4 (Green wire) and terminals No. 2 (Red wire) and No. 3 (White wire) at distributor connector. Measure resistance between terminal No. 4 (Black wire) and terminals No. 2 (Red wire) and No. 3 (Yellow wire) at distributor connector.
2. On all models, resistance should be 125-200 ohms with engine temperature at less than 122°F (50°C), or 160-235 ohms with engine temperature at more than 122°F (50°C). If resistance is not as specified, replace distributor. If resistance is as specified, go to next step.
3. Inspect wiring harness between ECM and distributor for open or short circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If circuit is okay, go to next step.
4. Remove distributor cap. Measure air gap of pick-up coils G1, G2 and NE. If air gap is .008-.020" (.20-.50 mm), replace ECM and retest. If air gap is not within specification, replace distributor.

1. Disconnect CKP sensor 2-pin connector. Using ohmmeter, measure resistance between terminals No. 1 (Red wire) and No. 2 (Green wire). Resistance should be 1630-2700 ohms (cold) or 2065-3225 (hot). If resistance is not as specified, replace CKP sensor. If resistance is as specified, go to next step.
2. Inspect NE2 signal circuit between ECM and CKP sensor for open or short circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If circuit is okay, go to next step.
3. Check CKP sensor for proper installation. Check CKP sensor signal plate for missing teeth. Replace components as necessary. If CKP sensor is installed properly and signal plate is okay, replace ECM and retest.

1. Connect scan tester to Data Link Connector (DLC) No. 3. see scheme 1 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 tester. If COMPL is displayed on scan tester and MIL is not illuminated, system is normal. If INCPL is displayed and MIL is not illuminated, repeat test drive procedure.

Scheme 8

1. Remove instrument panel fuse cover. Connect Lexus scan tester. Turn ignition on. Read EGR gas temperature. Temperature should be 50°F (10°C). If temperature is as specified, go to step 5). If temperature is not as specified, go to next step. If temperature displayed is 37.6°F (3.1°C), there is an open EGR gas temperature sensor circuit. Repair as necessary.
2. Disconnect EGR gas temperature sensor harness connector. Connector is located underneath throttle body. Connect 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, inspect sensor connectors and terminals. Repair as necessary. If connectors are okay, replace sensor and retest.
3. Remove jumper wire. Turn ignition off. Access ECM behind glove box. Connect Check Harness "A" (SST 09990-01000) to ECM. See TEST PREPARATION under SELF-DIAGNOSTIC SYSTEM. Connect jumper wire between ECM harness connector terminals No. 46 (Black/Red wire) and No. 65 (Brown wire) at ECM "B" connector. (Scheme 5) Turn ignition on. EGR gas temperature displayed should be 318.7°F (159.3°C).
4. If temperature displayed is as specified, locate and repair open in circuits between ECM and EGR gas temperature sensor. If temperature displayed is not as specified, replace ECM and retest.
5. Inspect vacuum hoses. Repair as necessary. If all hoses are okay, inspect VSV. On scan tester, select ACTIVE TEST mode. Check operation of VSV when activated by scan tester.
6. Start and run engine. With EGR system off, no air should flow from port "F". (Scheme 6) With EGR system on, air should flow from port "F". If valve operates correctly, go to step 10). If valve does not operate correctly, go to next step.
7. Remove EGR VSV. Using ohmmeter, measure resistance between valve terminals. Resistance should be 39-45 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 VSV.
8. Using jumper wires, apply battery voltage to VSV terminals. Air should flow from port "F". Remove jumper wires from VSV terminals. No air should pass through port "F". Replace VSV as necessary.
9. If valve meets all specifications in steps 7 and 8), inspect circuits between EGR VSV and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary.
10. Inspect EGR vacuum modulator. See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING article. Replace as necessary. If modulator is okay, inspect EGR valve. See SYSTEM & COMPONENT TESTING article. Replace as necessary. If EGR valve is okay, go to next step.
11. Ensure all components are connected. Inspect EGR gas temperature sensor. Start and run engine. Select ACTIVE TEST mode on scan tester (EGR system ON). Run engine at 4000 RPM for 3 minutes. Monitor EGR gas temperature. Temperature should be 284°F (140°C) or more.
12. If temperature is not as specified, replace sensor. If temperature is as specified, replace ECM and retest.

Diagnosis & Repair (Using OBD-II Scan Tester)

1. Disconnect EGR gas temperature sensor 2-pin connector. Connector is located at rear of intake plenum. Using ohmmeter, measure resistance between sensor terminals. If resistance is 600 k/ohms or less, go to next step. If resistance is more than 600 k/ohms, inspect sensor. See SYSTEM & COMPONENT TESTING article. Replace sensor as necessary.
2. Turn ignition on. Using DVOM, measure voltage between sensor harness connector terminals. If voltage is 4.5-5.5 volts, go to step 4). If voltage is not 4.4-5.5 volts, go to next step.
3. Access ECM behind glove box. Connect Check Harness "A" (SST 09990-01000) to ECM. See TEST PREPARATION under SELF-DIAGNOSTIC SYSTEM. Measure voltage between terminals No. 46 (Black/Red wire) and No. 65 (Brown wire) at ECM "B" connector. (Scheme 5) If voltage is 4.5-5.5 volts, inspect circuits between EGR gas temperature sensor and ECM for open circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If voltage is not 4.4-5.5 volts, replace ECM and retest.
4. Inspect all EGR system vacuum hoses. Replace as necessary. If vacuum hoses are okay, access ECM behind glove box. Connect Check Harness "A" (SST 09990-01000) to ECM connectors, leaving ECM disconnected. See TEST PREPARATION under SELF-DIAGNOSTIC SYSTEM. Turn ignition on. Connect a jumper wire between ground and terminal No. 75 (Gray wire) at ECM "B" connector.
5. Vacuum Switching Valve (VSV) is located under intake plenum. With jumper wire connected, VSV is on. Air should flow from port "F". (Scheme 6) Disconnect jumper wire. No air should flow from port "F". If valve operates correctly, go to step 9). If valve does not operate correctly, go to next step.
6. Remove EGR VSV. Using ohmmeter, measure resistance between valve terminals. Resistance should be 39-45 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 VSV.
7. Using jumper wires, apply battery voltage to VSV terminals. Air should flow from port "F". Remove jumper wires from VSV terminals. No air should pass through port "F". Replace VSV as necessary.
8. If valve meets all specifications in steps 6) and 7), inspect circuits between EGR VSV and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary.
9. Inspect EGR vacuum modulator. See SYSTEM & COMPONENT TESTING article. Replace as needed. If modulator is okay, inspect EGR valve. See SYSTEM & COMPONENT TESTING article. Replace EGR valve as necessary. If EGR valve is okay, go to next step.
10. Disconnect EGR gas temperature sensor connector. Start engine. Ensure engine is at normal operating temperature. Run engine at 4000 RPM for 3 minutes and measure resistance between EGR gas temperature sensor terminals. If resistance is 4300 ohms or less, replace ECM and retest. If resistance is more than 4300 ohms, replace sensor.

1. Connect scan tester to Data Link Connector (DLC) No. 3. see scheme 1 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 tester. If COMPL is displayed on scan tester and MIL is not illuminated, system is normal. If INCPL is displayed and MIL is not illuminated, repeat test drive procedure.

Diagnosis & Repair (Using Lexus Scan Tester)

1. Remove instrument panel fuse cover. Connect Lexus scan tester to Data Link Connector (DLC) No. 3. see scheme 1 Turn ignition and scan tester on. Read EGR gas temperature. Temperature should be 302°F (150°C) or less (not immediately after driving). If temperature is as specified, go to step 4). If temperature is not as specified, go to next step. If temperature displayed is 318.7°F (159.3°C), a short circuit exists in EGR gas temperature sensor circuit. Repair as necessary.
2. Disconnect EGR gas temperature sensor. Connector is located underneath throttle body. EGR gas temperature displayed should be 37.6°F (3.1°C). If temperature displayed is not as specified, go to next step. If temperature displayed is as specified, inspect sensor connectors and terminals. Repair as necessary. If connectors are okay, replace sensor and retest.
3. Turn ignition off. Access ECM behind glove box. Disconnect ECM "B" connector. (Scheme 5) Turn ignition on and observe scan tester display. EGR gas temperature displayed should be 37.6°F (3.1°C). If temperature displayed is not as specified, replace ECM and retest. If temperature displayed is as specified, repair wiring harness between ECM "B" connector and EGR gas temperature sensor connector.
4. Connect Check Harness "A" (SST 09990-01000) to ECM connectors, leaving ECM disconnected. See TEST PREPARATION under SELF-DIAGNOSTIC SYSTEM. Turn ignition on. Connect a jumper wire between ground and terminal No. 75 (Gray wire) at ECM "B" connector.
5. Vacuum Switching Valve (VSV) is located under intake plenum. With jumper wire connected, VSV is on. Air should flow from port "F". (Scheme 6) Disconnect jumper wire. No air should flow from port "F". If valve operates correctly, check EGR valve. See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING article. If valve does not operate correctly, go to next step.
6. Remove EGR VSV. Using ohmmeter, measure resistance between valve terminals. Resistance should be 39-45 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 VSV.
7. Using jumper wires, apply battery voltage to VSV terminals. Air should flow from port "F". Remove jumper wires from VSV terminals. No air should pass through port "F". Replace VSV as necessary.
8. If valve meets all specifications in steps 6) and 7), inspect circuits between EGR VSV and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary.

1. Disconnect EGR gas temperature sensor. Connector is located underneath throttle body. Using ohmmeter, measure resistance between sensor terminals. If resistance is 2500 ohms or more (not immediately after driving), go to next step. If resistance is less than 2500 ohms, replace sensor and retest.
2. Inspect circuits between EGR gas temperature sensor and ECM for short circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, go to next step.
3. Connect Check Harness "A" (SST 09990-01000) to ECM connectors, leaving ECM disconnected. See TEST PREPARATION under SELF-DIAGNOSTIC SYSTEM. Turn ignition on. Connect a jumper wire between ground and terminal No. 75 (Gray wire) at ECM "B" connector.
4. Vacuum Switching Valve (VSV) is located under intake plenum. With jumper wire connected, VSV is on. Air should flow from port "F". (Scheme 6) Disconnect jumper wire. No air should flow from port "F". If valve operates correctly, check EGR valve. See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING article. If valve does not operate correctly, go to next step.
5. Remove EGR VSV. Using ohmmeter, measure resistance between valve terminals. Resistance should be 39-45 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 VSV.
6. Using jumper wires, apply battery voltage to VSV terminals. Air should flow from port "F". Remove jumper wires from VSV terminals. No air should pass through port "F". Replace VSV as necessary.
7. If valve meets all specifications in steps 5) and 6), inspect circuits between EGR VSV and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace ECM and retest.

1. Remove instrument panel fuse cover. Connect scan tester to Data Link Connector (DLC) No. 3. see scheme 1 Start and run engine until normal operating temperature is reached. Ensure all accessories are off. Drive vehicle for 5-10 minutes at 31-40 MPH. Check for codes. If only DTC P0420 is displayed, go to next step. If other codes are displayed, diagnose and repair those codes first and retest.
2. Check heated oxygen sensor circuits. See «DTC P0130»(ref-22023-S30040550732001010300000) - HEATED OXYGEN SENSOR FAULT (BANK NO. 1, SENSOR NO. 1), DTC P0150 - HEATED OXYGEN SENSOR FAULT (BANK NO. 2, SENSOR NO. 1) circuit test. Replace oxygen sensors as necessary. If oxygen sensors are okay, replace catalytic converter and retest.

1. Connect Lexus scan tester to Data Link Connector (DLC) No. 3. see scheme 1 Turn ignition and scan tester on. Using scan tester, select ACTIVE TEST mode. Check operation of EVAP VSV when activated by scan tester. For VSV location, see VACUUM DIAGRAMS article.
2. With EVAP VSV on, air from port "E" should exhaust out port "F". (Scheme 6) With EVAP VSV off, air should not exhaust out port "F". If VSV operates as specified, go to step 5). If VSV does not operate as specified, go to next step.
3. Remove EVAP VSV. Using ohmmeter, measure resistance between VSV terminals. With VSV temperature at 68°F (20°C), resistance should be 27-33 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 VSV.
4. Using jumper wires, apply battery voltage to VSV terminals. Air from port "E" should exhaust out port "F". (Scheme 6) Disconnect jumper wires. Air should not exhaust out port "F". If VSV does not operate as specified, replace VSV. If VSV operates as specified, check for open or short circuit in wiring harness between EFI main relay and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace ECM and retest.
5. Check VSV vacuum hose connections. Repair as necessary. If hose connections are okay, check charcoal canister. See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING article. Replace as necessary.

1. Remove EVAP VSV. Using ohmmeter, measure resistance between VSV terminals. With VSV temperature at 68°F (20°C), resistance should be 27-33 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 VSV.
2. Using jumper wires, apply battery voltage to VSV terminals. Air from port "E" should exhaust out port "F". (Scheme 6) Disconnect jumper wires. Air should not exhaust out port "F". If VSV does not operate as specified, replace VSV. If VSV operates as specified, go to next step.
3. Access ECM behind glove box. Connect Check Harness "A" (SST 09990-01000) to ECM. See TEST PREPARATION under SELF-DIAGNOSTIC SYSTEM. Turn ignition on. Measure voltage between ground and terminal No. 74 (Green/Black wire) at ECM "B" connector. (Scheme 5) If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, check for open or short circuit between main relay and ECM. Repair wiring as necessary.
4. Check all EVAP system related vacuum hose connections. Repair as necessary. If hose connections are okay, check charcoal canister. See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING article. Replace as necessary. If canister is okay, replace ECM and retest.

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 TESTING article. Repair as necessary.
2. Place transmission shift lever in Neutral. Raise and support rear of vehicle. Access ECM behind glove box. Connect Check Harness "A" (SST 09990-01000) to ECM. See TEST PREPARATION under SELF-DIAGNOSTIC SYSTEM.
3. Disconnect power steering ECU 6-pin Blue connector and cruise control ECU 26-pin Gray connector. Power steering ECU is located on left behind right side of center console. Cruise control ECU is located behind center console.
4. Turn ignition on. Measure voltage between ground and terminal No. 2 (Pink wire) at ECM "A" connector while slowly rotating rear wheel by hand. (Scheme 5)
5. If voltage fluctuates from zero to 5.5 volts, replace ECM and retest. If voltage does not fluctuate, check wiring harness between instrument cluster and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary.

1. Check air intake hose between throttle body and cylinder head. Check for loose, damaged or cracked hose. Repair as necessary. If air intake hose is okay, go to next step.
2. Access ECM behind glove box. Connect Check Harness "A" (SST 09990-01000) to ECM connectors, leaving ECM disconnected. See TEST PREPARATION under SELF-DIAGNOSTIC SYSTEM. Turn ignition on. Measure voltage between ground and IAC valve terminals at ECM "B" connector. See «IDENTIFYING IAC VALVE TERMINALS AT ECM»(ref-22023-S36023471192001010300000) table. If all readings are 9-14 volts, go to step 4). If any reading is not 9-14 volts, go to next step. IDENTIFYING IAC VALVE TERMINALS AT ECM Terminal No. Wire Color 32 Blue/White 33 Green/Yellow 34 Light Green/Black 35 Blue/White
3. Disconnect IAC valve connector. Measure resistance between terminal B1 and terminals S1 and S3 at IAC valve. Also, measure resistance between terminal B2 and terminals S2 and S4. (Scheme 9) If each reading is 15-25 ohms (cold) or 20-30 ohms (hot), go to next step. If any reading is not 15-25 ohms (cold) or 20-30 ohms (hot), replace IAC valve.
4. Remove IAC valve. Connect a jumper wire between positive battery terminal and terminals B1 and B2 at IAC valve. Using another jumper wire, connect one end of jumper to negative battery terminal. Touch remaining end of jumper to IAC valve terminals S1, S2, S3 and S4 in that order. IAC valve should move to closed position.
5. Ensure jumper is still connected between positive battery terminal and terminals B1 and B2. Using another jumper wire, connect one end of jumper to negative battery terminal. Touch remaining end of jumper to IAC valve terminals S4, S3, S2, and S1 in that order. IAC valve should move to open position.
6. If IAC valve does not operate as specified, replace IAC valve. If IAC valve operates as specified, check for open or short circuit in wiring harness between main relay, IAC valve and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, no problem is indicated at this time. Diagnose by symptom. See TROUBLE SHOOTING - NO CODES article.

Scheme 9

1. Remove instrument panel fuse cover. Connect Lexus scan tester to Data Link Connector (DLC) No. 3. see scheme 1 Disconnect TP sensor connector. Connect a jumper wire between terminals No. 1 (Brown wire) and No. 2 (Red wire at TP sensor harness connector.
2. Turn ignition on. Turn scan tester on. Using scan tester, read CTP switch signal. If CTP switch signal is off, remove jumper wire and go to next step. If CTP switch signal is on, check TP sensor connector. Repair as necessary and retest. If connector is okay, replace TPsensor.
3. Access ECM behind glove box. Turn ignition off. Connect Check Harness "A" (SST 09990-01000) to ECM. See TEST PREPARATION under SELF-DIAGNOSTIC SYSTEM. Connect a jumper wire between terminals No. 64 (Red wire on and No. 65) (Brown wire) at ECM "B" connector. (Scheme 5)
4. Turn ignition on. Using scan tester, read CTP switch signal. If CTP switch signal is off, replace ECM and retest. If CTP switch signal is on, locate and repair open circuit between ECM and TP sensor.

1. Disconnect TP sensor connector. Turn ignition on. Using DVOM, measure voltage between terminals No. 1 (Brown wire) and No. 2 ( Red wire) at TP sensor harness connector.
2. If voltage is not 9-14 volts, check for open in wiring harness between ECM and TP sensor. Repair as necessary. If wiring is okay, replace ECM and retest. If voltage is 9-14 volts, check TP sensor connector. Repair as necessary. If connector is okay, replace TP sensor and retest.

1. If not using a Lexus scan tester, go to step 2). If using Lexus scan tester, remove instrument panel fuse cover. Connect Lexus scan tester to Data Link Connector (DLC) No. 3. see scheme 1 On scan tester, select ACTIVE TEST mode. Activate fuel pump. Fuel pressure should be felt at fuel inlet hose at fuel rail. If fuel pressure is present, go to step 8). If no fuel pressure is present, go to step 3).
2. Locate fuel pump 2-pin connector. Connector is located in trunk behind front trim panel. Connect a jumper wire between positive battery terminal and terminal No. 1 ( or Green wire) at fuel pump connector. Connect another jumper wire between negative battery terminal and terminal No. 2 (White/Black wire) at fuel pump connector. Pressure should be felt at fuel inlet hose at fuel rail. If fuel pressure is present, go to step 8). If no fuel pressure is present, go to next step.
3. Remove trim panel from left side of trunk area. Disconnect fuel pump ECU 5-pin connector. Measure voltage between ground and terminal No. 4 (Black/Red wire) at fuel pump ECU harness connector. If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, check for open or short circuit in wiring harness between main relay and fuel pump ECU. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary.
4. With ignition switch in START position, measure voltage between terminals No. 1 (White/Black) and No. 3 (Red/Green wire on) at fuel pump ECU harness connector. If voltage is 4.5-5.5 volts, go to step 6). If voltage is not 4.5-5.5 volts, go to next step.
5. Check for an open or short in FPC circuit (Red/Green wire) between fuel pump ECU and terminal No. 22 at ECM "A" connector. Also, check for an open or short in ground circuit (White/Black wire) between ground and fuel pump ECU. Repair as necessary. If wiring is okay, replace ECM and retest.
6. Locate fuel pump 2-pin connector. Connector is located in trunk behind front trim panel. Measure resistance between fuel pump connector terminals. If resistance is.2-3.0 ohms, go to next step. If resistance is not.2-3.0 ohms, replace fuel pump.
7. Check for an open or short circuit between terminal No. 5 (Green wire) at fuel pump ECU, fuel pump and ground. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace fuel pump ECU and retest.
8. Check for an open or short circuit in wiring harness between fuel pump ECU and terminal No. 21 (Pink wire) at ECM "A" connector. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace ECM and retest.

1. Check for spark at misfiring cylinder. See IGNITION CHECKS in BASIC DIAGNOSTIC PROCEDURES article. If spark is present, go to next step. If spark is not present, go to step 4).
2. Check for open or short in IGF circuit between ECM and ignitor. Ignitor is located on right side of engine compartment, near ignition coil. See appropriate wiring diagram in WIRING DIAGRAMS. Repair as necessary. If circuit is okay, go to next step.
3. Disconnect 5-pin ignitor connector. Access ECM behind glove box. Connect Check Harness "A" (SST 09990-01000) to ECM. See TEST PREPARATION under SELF-DIAGNOSTIC SYSTEM. Turn ignition on. Measure voltage between ground and terminal No. 58 (Red/Yellow wire) at ECM "B" connector. (Scheme 5) 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 circuit (White/Green wire) between ECM and ignitor. See appropriate wiring diagram in WIRING DIAGRAMS. Repair as necessary. If circuit is okay, go to next step.
5. Measure voltage between ground and terminal No. 57 (White/Green wire) at ECM "B" 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 5-pin ignitor connector. Measure voltage between ground and terminal No. 57 (White/Green wire) at ECM "B" 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.
7. Turn ignition on. Measure voltage between ground and terminal No. 3 (Black/Orange wire) at ignitor wiring harness connector. If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, check and repair ignitor power source circuit. See appropriate wiring diagram in WIRING DIAGRAMS 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 TESTING article. Replace coil as necessary. If coil is okay, replace ignitor.

See DTC P0335 OR P1335 - CRANKSHAFT POSITION (CKP) SENSOR CIRCUIT test.

1. Access ECM harness connectors behind glove box. Connect Check Harness "A" (SST 09990-01000) to ECM. See TEST PREPARATION under SELF-DIAGNOSTIC SYSTEM. Turn ignition on. Remove air intake duct. Disconnect sub-throttle actuator connector. (Scheme 10) Measure voltage between ground and terminal No. 42 (Yellow/Blue wire) at ECM "B" connector. (Scheme 5)
2. Voltage should be.3-.8 volt (throttle closed) and 3.2-4.9 volts (throttle open). Measure voltage between ground and terminal No. 63 (Red/Black wire) at ECM "B" connector. Voltage should be 0-3 volts (throttle closed) and 9-14 volts (throttle open). If voltage is not as specified, go to next step. If voltage is as specified, no problem is detected at this time. Problem is intermittent.
3. Disconnect SUB-TP sensor connector. (Scheme 10) Measure resistance between terminals No. 1 (Brown wire) and No. 3 (Yellow/Blue wire) at SUB-TP sensor. Resistance should be 200-800 ohms (throttle closed) and 2400-11,200 ohms (throttle open).
4. Measure resistance between terminals No. 1 (Brown wire) and No. 2 (Red/Black wire) at SUB-TP sensor. Resistance should be less than 500 ohms (throttle closed) and infinite (throttle open). If resistances are as specified, go to next step. If resistances are not as specified, adjust SUB-TP sensor. See ON-VEHICLE ADJUSTMENTS article. If adjustment is okay, replace sensor.
5. Check for open or short in wiring harness between SUB-TP sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace ECM and retest.

Scheme 10

If only DTC P1401 is displayed, replace SUB-TP sensor and retest. If other codes are displayed, diagnose and repair those codes first and retest.

1. Remove instrument panel fuse cover. Connect Lexus scan tester to Data Link Connector (DLC) No. 3. see scheme 1 Turn scan tester on. Turn ignition on. Using scan tester, read STA signal with ignition on and then while cranking starter. With ignition on, STA signal should be off. With ignition switch in START position, STA signal should be on. If STA signal is as specified, no problem is indicated at this time. Diagnose by symptom. See TROUBLE SHOOTING - NO CODES article. If STA signal is not as specified, go to next step.
2. Check for open in wiring harness between ECM and starter relay. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary. If wiring is okay, replace ECM and retest.

1. Access ECM behind glove box. Connect Check Harness "A" (SST 09990-01000) to ECM. See TEST PREPARATION under SELF-DIAGNOSTIC SYSTEM. Measure voltage between ground and terminal No. 33 (Black/Yellow wire at ECM "A" connector. (Scheme 5) 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 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.

If only DTC P1605 is displayed, replace ECM and retest. If other codes are displayed, diagnose and repair those codes first and retest.

1. Check park/neutral position switch. See ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING article. Replace switch as necessary. If switch is okay, go to next step.
2. Access ECM behind glove box. Connect Check Harness "A" (SST 09990-01000) to ECM. See TEST PREPARATION under SELF-DIAGNOSTIC SYSTEM. Turn ignition on. Measure voltage between ground and terminal No. 76 (Black/White wire) at ECM "B" connector. (Scheme 5)
3. With shift lever in "P" or "N" position, voltage should be zero volts. With shift lever in any other position, voltage should be 9-14 volts. If voltage is as specified, replace ECM and retest. If voltage is not as specified, check for open or short circuit in wiring harness between ECM and park/neutral position switch. See appropriate wiring diagram in WIRING DIAGRAMS article.