Engine Controls - Tests W/codes - Obd-Ii: Diagnosis Lexus ES XV10 рестайлинг

MALFUNCTION INDICATOR LIGHT (MIL) INSPECTION

Note. The Malfunction Indicator Light (MIL) on the instrument panel may also be referred to as CHECK ENGINE light. Inspect MIL to ensure it is operational and will come on if a trouble code is stored.

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 panel and wiring circuit between MIL and ECM. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-21770) article. See «ECM LOCATION»(ref-21746-S09136794882001010300000) .
2. Start engine and ensure MIL goes off. If MIL remains on with engine running, a malfunction is detected. Proceed to «RETRIEVING TROUBLE CODES»(ref-21746-S24241737752001010300000) .

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 Trouble Codes Connect appropriate OBD-II scan tester. Retrieve codes and record any freeze-frame data. See «RETRIEVING TROUBLE CODES»(ref-21746-S24241737752001010300000) .
3. Clear Trouble Codes Clear codes using scan tester. See «CLEARING TROUBLE CODES»(ref-21746-S38384399982001010300000) .
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 Trouble Codes Perform diagnosis and repair procedures as needed. See appropriate DIAGNOSTIC TESTING. If no codes are present, proceed to «TESTS W/O CODES»(ref-21769) article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.).
7. Verification Procedure

After repairs have been completed, clear all trouble codes. See CLEARING TROUBLE CODES . Perform road test. Ensure no trouble codes are present and all symptoms and/or complaints have been repaired.

RETRIEVING TROUBLE CODES

Note. Trouble codes may be retrieved using Lexus scan tester or On-Board Diagnostic (OBD-II) scan tester that complies with SAE standard J1978. 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 trouble codes.

Normal Mode is used to retrieve trouble codes from Engine Control Module (ECM). Check Mode is used to check for trouble codes when operating vehicle to simulate conditions in which trouble code 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 trouble codes and freeze frame data will be erased. DO NOT switch modes until all trouble codes and freeze frame data are recorded.

CLEARING TROUBLE CODES

1. After performing repairs, clear ECM memory of all stored trouble codes and freeze frame data. Trouble codes and freeze frame data may be cleared by using scan tester and scan tester manufacturer's instructions. NOTE: If using Lexus Scan Tester, trouble codes and freeze frame data may be cleared by switching from Check Mode to Normal Mode or from Normal Mode to Check Mode.
2. Trouble codes and freeze frame data may also be cleared by removing EFI fuse from junction block located in engine compartment.
3. Trouble codes and freeze frame data may also be cleared by disconnecting negative battery cable. However, other memory functions (clock, radio, alarm, seats, etc.) will be canceled and must be reset.

TROUBLE CODE IDENTIFICATION

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»(ref-21770) 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-21746-S05032807992001010300000). 3 VOLTAGE & RESISTANCE SPECIFICATIONS table. (Scheme 24) If voltage and resistance readings are not as specified, check wiring circuit. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-21770) 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 24

DIAGNOSTIC TESTING (ES300)

Note. For Electronic Control Module (ECM) connector, wire color and circuit identification see scheme 6under CONNECTOR IDENTIFICATION and appropriate wiring diagram in appropriate WIRING DIAGRAMS article.

Circuit Description

MAF sensor uses a platinum hot wire maintained at a constant temperature. Airflow past sensor affects temperature and current flow through sensor. Code is set when ECM detects a open or short circuit with engine speed at 4000 RPM or less. ECM will operate in fail-safe mode if Code P0100 is set. Possible causes are

1. MAF open or short circuit.
2. MAF sensor malfunction.
3. ECM malfunction.

Diagnosis & Repair Procedure

1. Remove instrument panel fuse cover. Connect scan tester to Data Link Connector (DLC) No. 3. see scheme 1 Start vehicle engine an d allow it to idle. Turn on scan tester. Monitor MAF flow rate. If scan tester reading is 0.0 gm/sec., go to next step. If reading is 9.0-21.0 gm/sec. once engine is at normal operating temperature, go to step 5).
2. Disconnect MAF sensor harness connector. Ensure ignition is on. Using DVOM, measure voltage between ground and terminal No. 1 (Black/Orange 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/Orange wire between MAF sensor connector and ECM.
3. Access ECM behind glove box. Start engine. Backprobing ECM connector, check voltage between ground and terminal No. 8 (Red wire) at ECM E8 connector. see scheme 6 If voltage is 1.1-1.5 volts, rep lace ECM and retest.
4. If voltage is not 1.1-1.5 volts, locate and repair open or short circuit in Red wire between MAF sensor and ECM. If Red wire is okay, replace MAF sensor and retest.
5. Access ECM behind glove box. Turn ignition off. Backprobing ECM connector, check for continuity between ground and terminal No. 7 (Red/Black wire) at ECM E9 connector. If continuity does not exist, replace ECM and retest. If continuity exists, locate and repair open in Red/Black wire between MAF sensor and ECM. If Red/Black wire is okay, replace MAF sensor.

If only Code P0101 is displayed, replace MAF sensor and retest. If other codes are displayed, diagnose and repair those codes first and retest.

The IAT sensor is a thermistor built into the MAF sensor to monitor air temperature flowing through MAF sensor. Code is set when ECM detects an open or short circuit. ECM will operate in fail-safe mode if code P0110 is set. Possible causes are

1. IAT sensor open or short circuit.
2. IAT sensor malfunction.
3. ECM malfunction.

Note. If Codes P0110, P0115 and P0120 are output together, inspect ECM terminal E2 (ground) circuit. Repair as necessary. See appropriate wiring diagram in WIRING DIAGRAMS article.

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 (Blue/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 not 284°F (140°C), turn ignition off. Remove jumper wire. Access ECM behind glove box. Connect jumper wire between terminals No. 21 (Blue/Black wire) and No. 22 (Brown wire) at ECM E8 connector. see scheme 6
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 ECM harness connector E8. 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.

The ECT sensor is a thermistor sensor that monitors coolant temperature. Code is set when ECM detects a open or short circuit. Possible causes are

1. ECT sensor open or short circuit.
2. ECT sensor malfunction.
3. ECM malfunction.

Note. If Codes P0110, P0115 and P0120 are output together, inspect ECM terminal E2 (ground) circuit. Repair as necessary. See appropriate wiring diagram in WIRING DIAGRAMS article.

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 MAF sensor harness connector. Connect a jumper wire between terminals No. 2 (Green/Black 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 not 284°F (140°C), turn ignition off. Remove jumper wire. Access ECM behind glove box. Connect jumper wire between terminals No. 20 (Green/Black wire) and No. 22 (Brown wire) at ECM E8 connector. see scheme 6
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 ECM E8 connector. 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 Code P0116 is displayed, replace ECT sensor and retest. If other codes are displayed, diagnose and repair those codes first and retest.

The TP sensor is variable resistor that monitors throttle opening. The ECM determines vehicle driving condition and adjusts air/fuel mixture accordingly. Code is set when ECM consistently detects less than .1 volt from VTA circuit and closed throttle position switch is off. Code can also be set if ECM consistently detects 4.9 volts or more. Code P0120 will not set if there is an open in IDL circuit. Possible causes are

1. TP sensor open or short circuit.
2. TP sensor malfunction.
3. ECM malfunction.

Note. If Codes P0110, P0115 and P0120 are output together, inspect ECM terminal E2 (ground) circuit. Repair as necessary. See appropriate wiring diagram in WIRING DIAGRAMS article.

Diagnosis & Repair Procedure (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 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. Turn ignition off. Monitor closed throttle position switch position. With throttle valve fully closed, switch position should be ON. With throttle valve fully open, switch position should be OFF. If switch position is as specified, go to step 5). If switch position is not as specified, go to next step.
3. 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 6).
4. 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 4250-8250 ohms. Measure resistance between terminals No. 1 (Brown wire) and No. 3 (Black/Yellow wire). Resistance should be 300-6300 ohms with throttle fully closed and 3500-10,300 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.
5. Connect TP sensor harness connector. Access ECM harness connectors behind glove box. Turn ignition on. Backprobing ECM harness connector, measure voltage between terminals No. 7 (Black/Yellow wire) and No. 22 (Brown wire) at ECM E8 connector. see scheme 6 Voltage should be.3-.8 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. If voltages are not as specified, locate and repair open or short circuit in Black/Yellow wire.
6. Access ECM harness connectors behind glove box. Turn ignition on. Backprobing ECM harness connector, measure voltage between terminals No. 1 (Blue/Red wire) and No. 22 (Brown wire) at ECM E8 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.

Diagnosis & Repair Procedure (Using OBD-II Scan Tester)

1. Remove instrument panel fuse cover. Connect OBD-II 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.
2. 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.
3. Access ECM harness connectors behind glove box. Turn ignition on. Backprobing ECM harness connector, measure voltage between terminals No. 32 (Blue/White wire) at ECM E7 connector and No. 22 (Brown wire) at ECM E8 connector. see scheme 6
4. With throttle valve fully closed, voltage should be 0-3 volts. With throttle valve fully open, voltage should be 9-14 volts. If voltage is as specified, go to step 7). If voltage is not as specified, go to next step.
5. 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 8).
6. 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 4250-8250 ohms. Measure resistance between terminals No. 1 (Brown wire) and No. 3 (Black/Yellow wire). Resistance should be 300-6300 ohms with throttle fully closed and 3500-10,300 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.
7. Connect TP sensor harness connector. Access ECM harness connectors behind glove box. Turn ignition on. Backprobing ECM harness connector, measure voltage between terminals No. 7 (Black/Yellow wire) and No. 22 (Brown wire) at ECM E8 connector. see scheme 6 Voltage should be.3-.8 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. If voltages are not as specified, check for open or short circuit in Black/Yellow wire or Brown wire. Repair as necessary.
8. Access ECM harness connectors behind glove box. Turn ignition on. Backprobing ECM harness connector, measure voltage between terminals No. 1 (Blue/Red wire) and No. 22 (Brown wire) at ECM E8 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 Code P0121 is displayed, replace TP sensor and retest. If other codes are displayed, diagnose and repair those codes first and retest.

The oxygen sensor monitors exhaust gas oxygen content and delivers an input signal to ECM. The ECM uses input signal to determine fuel injection system operation. Sensors include heater. Code is set when sensor does not output a rich condition once engine is at normal operating temperature, engine speed of 1500 RPM or more, and vehicle speed is at least 25 MPH for at least 2 minutes. Possible causes are

1. Open or short in oxygen sensor circuit.
2. Heated oxygen sensor malfunction.

1. Remove instrument panel fuse cover. Connect scan tester to Data Link Connector (DLC) No. 3. see scheme 1 Start engine and warm t o normal operating temperature. Turn scan tester on. Monitor each oxygen sensor. Snap accelerate engine 3 times. Sensors should indicate a rich signal (.45 volts 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.

Code P0130 is set when bank No. 1, sensor No. 1 voltage remains at .4-.55 volts during idle. Code P0150 is set when bank No. 2, sensor No. 1 voltage remains at .4-.55 volts once engine is at normal operating temperature. Possible causes are

1. Heated oxygen sensor malfunction.
2. Fuel trim malfunction.

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 1 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 1 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»(ref-21770) 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 volts or less, +20 trim) or rich condition (.4 volts or more, -20 trim), see «CODE P0170»(ref-21746-S26081553042001010300000), FUEL TRIM MALFUNCTION.
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 Code P0133 or P0153 is displayed, replace oxygen sensor and retest. If other codes are displayed, diagnose and repair those codes first and retest.

Diagnosis & Repair

1. Access ECM harness connectors behind glove box. Turn ignition on. Using DVOM, backprobe ECM harness connector. If Code P0135 is set, measure voltage between ground and terminal No. 10 (Violet wire) at ECM E9 connector. If Code P0141 is set, measure voltage between ground and terminal No. 11 (Blue/Black wire) at ECM E9 connector. If Code P0155 is set, measure voltage between ground and terminal No. 25 (Purple/Black wire) at ECM E10 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-21746-S38125258822001010300000) table. IDENTIFYING OXYGEN SENSOR HEATER TERMINALS Application Terminal No. 1 Terminal No. 2 Bank 1, Sensor 1 Blue/Black Wire Black/Orange Wire Bank 1, Sensor 2 Purple/Black Wire Black/Orange Wire Bank 2, Sensor 1 Violet Wire Black/Orange Wire
3. With sensor temperature at 68°F (20°C), resistance should be 11-16 ohms. If resistance as specified, inspect circuits between main relay, sensor and ECM. See appropriate wiring diagram in appropriate «WIRING DIAGRAMS»(ref-21770) article. Repair as necessary. If resistance is not as specified, replace sensor and retest.

1. If any other codes are displayed other than Code P0136, diagnose and repair those codes first. If only Code P0136 is displayed, inspect circuits between ECM and sensor for opens or shorts. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-21770) 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 2500 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.

Fuel trim refers to feedback compensation value compared against basic injection time. Fuel trim includes short-term and long-term fuel trim.

Code is set when both short-term and long-term fuel trim are lean or rich beyond a certain value. Possible causes are

1. Air intake.
2. Fuel line pressure.
3. Injector blockage or leak.
4. Heated oxygen sensor malfunction.
5. Mass Airflow (MAF) sensor.
6. Engine coolant temperature sensor.

1. Inspect all air induction components. Repair as necessary. 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 volts or less, +20 trim) or rich condition (.4 volts or more, -20 trim), go to next step. If results are other than shown, see CODE P0130, HEATED OXYGEN SENSOR FAULT (BANK NO. 1, SENSOR NO. 1), CODE P0150, HEATED OXYGEN SENSOR FAULT (BANK NO. 2, SENSOR NO. 1) diagnostic test.
3. Inspect fuel pressure. See «BASIC TESTING»(ref-21759) article. Repair as necessary. If fuel pressure is okay, inspect fuel injector performance. See «SYSTEM/COMPONENT TESTS»(ref-21745) article. Replace injectors as necessary.
4. If all injectors are okay, inspect Mass Airflow (MAF) sensor and Engine Coolant Temperature (ECT) sensor. See appropriate «SYSTEM/COMPONENT TESTS»(ref-21745) article. Replace as necessary. If both components are okay, inspect ignition system. See «BASIC TESTING»(ref-21759) article. Repair as necessary. If ignition system is okay, replace ECM and retest.

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

Code 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 appropriate «BASIC TESTING»(ref-21759) article. Repair as necessary. If ignition system is okay, ensure ignition is off.
2. Access ECM harness connectors behind glove box. Turn ignition on. Using DVOM, backprobe ECM connector. Measure voltage between ground and injector terminals at ECM E7 connector. See «IDENTIFYING INJECTOR TERMINALS»(ref-21746-S29695413032001010300000) 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 10 White 2 9 Yellow 3 8 Green 4 7 Blue 5 6 Red 6 5 Green (1) Terminals are located in ECM E7 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»(ref-21770) article. Repair as necessary. If resistance is not 13.4-14.2 ohms, replace injector.
4. Inspect fuel pressure. See «BASIC TESTING»(ref-21759) article. Repair as necessary. If fuel pressure is okay, inspect fuel injector performance. See «SYSTEM/COMPONENT TESTS»(ref-21745) article. Replace as necessary.
5. If all injectors are okay, inspect EGR system. See appropriate «SYSTEM/COMPONENT TESTS»(ref-21745) article. Repair as necessary. If EGR system is okay, inspect MAF sensor and ECT sensor. See appropriate «SYSTEM/COMPONENT TESTS»(ref-21745) article. Replace as necessary. If both components are okay, check engine compression, valve clearance and valve timing. See «BASIC TESTING»(ref-21759) article. Repair as necessary.

See CODE P0300 , RANDOM MISFIRE DETECTED.

See CODE P0300 , RANDOM MISFIRE DETECTED.

Knock sensors are located on either side of cylinder block. Sensor generates voltage when engine block vibrates due to knocking. Code is set when there is no knock sensor signal to ECM with engine speed of 2000 RPM or more. Code P0325 is for knock sensor No. 1 on right bank. Code P0330 is knock sensor No. 2 on left bank. Possible causes are

1. Open or short in knock sensor circuit.
2. Knock sensor (loose).
3. ECM malfunction.

Scheme 25

1. Remove instrument panel fuse cover. Connect scan tester to Data Link Connector (DLC) No. 3. see scheme 1 Disconnect ED1 connector. ED1 connector is a wire-to-wire connector located left side of engine compartment, near front of cylinder head. Connector is Dark Gray 4-pin connector.
2. Connect a jumper wire between terminal No. 1 of male connector to terminal No. 2 of female connector. Connect another jumper wire between terminal No. 2 of male connector to terminal No. 1 of female connector. (Scheme 25) Turn ignition on. Clear trouble codes. See «CLEARING TROUBLE CODES»(ref-21746-S38384399982001010300000). Start and warm engine to normal operating temperature.
3. Snap accelerate engine 3 times. Retrieve trouble codes. See «RETRIEVING TROUBLE CODES»(ref-21746-S24241737752001010300000). If same code is repeated as before, go to next step. If code has changed, go to step 5).
4. Inspect circuit(s) between ED1 connector and ECM harness connector for open or short circuit. Repair as necessary. If circuits are okay, replace ECM and retest.
5. Inspect circuit(s) between ED1 connector and knock sensor for open or short circuit. If Code P0325 has changed to Code P0330, check knock sensor circuit on right bank. If Code P0330 changed to Code P0325, check knock sensor circuit on left bank. Repair as necessary. If harness is okay, replace knock sensor.

The CKP sensor is a pick-up coil mounted next to crankshaft pulley. A 34-tooth signal plate is mounted to crankshaft. Code P0335 is set if no cranking signal is received by ECM from sensor. Code P1335 is set if no engine running signal is received by ECM from sensor. Possible causes are

1. CKP sensor open or short circuit.
2. CKP sensor malfunction.
3. Starter malfunction.
4. ECM malfunction.

1. Disconnect CKP sensor harness connector. Using ohmmeter, measure resistance between sensor connector terminals. Resistance should be 1630-2740 ohms (cold sensor) or 2065-3225 ohms (hot sensor).
2. Replace sensor as necessary. If sensor is okay, inspect circuits between ECM and CKP sensor for open or short circuit. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-21770) article. Repair as necessary. If both circuits are okay, remove and inspect sensor. Also, inspect signal plate. Replace as necessary. If both components are okay, replace ECM and retest.

The CMP sensor is a pick-up coil mounted in outer corner of front cylinder head, just below valve cover. A one tooth signal plate is mounted to outer camshaft. Code is set when either no cranking or engine running signal is received by ECM from sensor. Possible causes are

1. CMP sensor open or short circuit.
2. CMP sensor malfunction.
3. Starter malfunction.
4. ECM malfunction.

1. Disconnect CKP sensor harness connector. Using ohmmeter, measure resistance between sensor connector terminals. Resistance should be 835-1400 ohms (cold sensor) or 1060-1645 ohms (hot sensor).
2. Replace sensor as necessary. If sensor is okay, inspect circuits between ECM and CMP sensor for open or short circuit. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-21770) article. Repair as necessary. If both circuits are okay, remove and inspect sensor. Also, inspect signal plate. Replace as necessary. If both components are okay, replace ECM and retest.

The EGR system recirculates exhaust gas through intake system to reduce combustion temperature and NOx emissions. The amount of EGR valve opening is regulated by the EGR vacuum modulator according to engine load. Vacuum source to valve is controlled by the Vacuum Switching Valve (VSV), which is operated by ECM.

The EGR valve is closed (VSV on) under the following conditions

1. Coolant temperature less than 140°F (60°C).
2. Vehicle under deceleration.
3. Light engine load.
4. Engine racing.

Code is set when EGR gas temperature sensor value does not exceed 72°F (40°C) above ambient air temperature after vehicle is operated for 3-5 minutes at 50 MPH or more. Possible causes are

1. EGR valve stuck closed.
2. VSV short circuit.
3. EGR gas temperature sensor open circuit.
4. EGR vacuum hose disconnected.
5. ECM malfunction.

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 (may also be known as I/M FLAG). 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. 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 jumper wire between ECM harness connector terminals No. 14 (Gray/Yellow wire) at ECM E9 connector and No. 22 (Brown wire) at ECM E8 connector. see scheme 6 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. VSV is located under intake plenum cover.
6. Start and run engine. With EGR system off, air should exhaust from small filter on end of valve. With EGR system on, air should pass through valve and exit vacuum fitting at bottom of valve. 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 26-46 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 exhaust from small filter on end of valve. Remove jumper wires from VSV terminals. Air should pass through valve. 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»(ref-21770) article. Repair as necessary.
10. Inspect EGR vacuum modulator. See appropriate «SYSTEM/COMPONENT TESTS»(ref-21745). Replace as necessary. If modulator is okay, inspect EGR valve. See «SYSTEM/COMPONENT TESTS»(ref-21745). 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. Connector is located underneath throttle body. 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 TESTS»(ref-21745). 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. Using DVOM, backprobe harness connectors and measure voltage between ECM harness connector terminals No. 14 (Gray/Yellow wire) at ECM E9 connector and No. 22 (Brown wire) at ECM E8 connector. see scheme 6 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»(ref-21770) 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. Access ECM behind glove box. Ensure ignition is off. Disconnect ECM E9 harness connector. Turn ignition on. Connect a jumper wire between ground and terminal No. 12 (Black/Blue wire) at ECM E9 connector.
5. Vacuum Switching Valve (VSV) is located under intake plenum cover. With jumper wire connected, VSV is on. Air should exhaust through filter on end of valve. Disconnect jumper wire. Air should pass through valve and exit vacuum fitting at bottom of valve. If valve operates correctly, go to step 9).
6. If valve does not operate correctly, turn ignition off. Remove EGR VSV. Using ohmmeter, measure resistance between valve terminals. Resistance should be 26-46 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 exhaust from small filter on end of valve. Remove jumper wires from VSV terminals. Air should pass through valve. 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»(ref-21770) article. Repair as necessary.
9. Inspect EGR vacuum modulator. See appropriate «SYSTEM/COMPONENT TESTS»(ref-21745). Replace as needed. If modulator is okay, inspect EGR valve. See «SYSTEM/COMPONENT TESTS»(ref-21745). 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.

The EGR system recirculates exhaust gas through intake system to reduce combustion temperature and NOx emissions. The amount of EGR valve opening is regulated by the EGR vacuum modulator according to engine load. Vacuum source to valve is controlled by the Vacuum Switching Valve (VSV), which is operated by ECM.

The EGR valve is closed (VSV on) under the following conditions

1. Coolant temperature less than 140°F (60°C).
2. Vehicle under deceleration.
3. Light engine load.
4. Engine racing.

Code is set when EGR gas temperature sensor value is high during EGR cut-off when engine is cold, or if EGR valve is always open. Possible causes are

1. EGR valve stuck open.
2. VSV open circuit.
3. EGR gas temperature sensor short circuit.
4. ECM malfunction.

1. Remove instrument panel fuse cover. Connect Lexus scan tester to Data Link Connector (DLC) No. 3. see scheme 1 Turn ignition an d 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 E9 connector. see scheme 6 Turn ignition on and observe s can 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 E9 connector and EGR gas temperature sensor connector.
4. On scan tester, select ACTIVE TEST mode. Check operation of VSV when activated by scan tester. VSV is located under intake plenum cover. Start and run engine. With EGR system off, air should exhaust from small filter on end of valve. With EGR system on, air should pass through valve and exit vacuum fitting at bottom of valve. If valve does not operate correctly, go to next step. If valve operates correctly, inspect EGR valve. See «SYSTEM/COMPONENT TESTS»(ref-21745). Replace as necessary.
5. Remove EGR VSV. Using ohmmeter, measure resistance between valve terminals. Resistance should be 26-46 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 exhaust from small filter on end of valve. Remove jumper wires from VSV terminals. Air should pass through valve. 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»(ref-21770) 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. If resistance is 200 ohms or less, a short circuit exists in EGR gas temperature sensor circuit. Repair as necessary.
2. Inspect circuits between EGR gas temperature sensor and ECM for short circuit. See appropriate wiring diagram in appropriate «WIRING DIAGRAMS»(ref-21770) article. Repair as necessary. If wiring is okay, go to next step.
3. Access ECM behind glove box. Ensure ignition is off. Disconnect ECM E9 harness connector. see scheme 6 Turn ignition on. Connect a jumper wire between ground and terminal No. 12 (Black/Blue wire) at ECM E9 connector. VSV is located under intake plenum cover.
4. With jumper wire connected, VSV is on. Air should exhaust through filter on end of valve. Disconnect jumper wire. Air should pass through valve and exit vacuum fitting at bottom of valve. If valve does not operate correctly, go to next step. If valve operates correctly, inspect EGR valve. See «SYSTEM/COMPONENT TESTS»(ref-21745). Replace EGR valve as necessary.
5. Turn ignition off. Remove EGR VSV. Using ohmmeter, measure resistance between VSV terminals. Resistance should be 26-46 ohms. Measure resistance between each terminal and body of VSV. 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 exhaust from small filter on end of valve. Remove jumper wires from VSV terminals. Air should pass through valve. 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»(ref-21770) article. Repair as necessary. If wiring is okay, replace ECM and retest.

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.

Code is set if after driving vehicle for 5 minutes at 20-50 MPH and engine is at normal operating temperature, oxygen sensor waveforms are the same. Possible causes are

1. Catalytic converter malfunction.
2. Open or short circuit in oxygen sensor circuit.
3. Oxygen sensor malfunction.

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 Code 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 CODE P0130, HEATED OXYGEN SENSOR FAULT (BANK NO. 1, SENSOR NO. 1), CODE P0150, HEATED OXYGEN SENSOR FAULT (BANK NO. 2, SENSOR NO. 1) diagnostic test. Replace oxygen sensors as necessary. If oxygen sensors are okay, replace catalytic converter and retest.

To reduce HC emissions, evaporated fuel from fuel tank is routed through charcoal canister to the intake chamber for combustion in cylinders. ECM changes the purge control Vacuum Switching Valve (VSV) duty signal so the intake quantity of HC emissions is appropriate for the driving condition (engine load, engine speed, etc.) after engine is warmed up.

Code is set if the proper response to the ECM command does not occur. Possible causes are

1. Purge control VSV.
2. Open or short circuit in purge control VSV circuit.
3. Disconnected or blocked vacuum hose.
4. Charcoal canister.

1. Remove instrument panel fuse cover. Connect Lexus scan tester to Data Link Connector (DLC) No. 3. Turn ignition and scan tester on. Using scan tester, select ACTIVE TEST mode. Check operation of VSV when activated by scan tester. VSV is located under intake plenum cover.
2. With purge control VSV on, air from pipe "E" should exhaust out pipe "F". (Scheme 26) With purge control VSV off, air should not exhaust out pipe "F". If VSV operates as specified, go to step 5). If VSV does not operate as specified, go to next step.
3. Remove purge control 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 pipe "E" should exhaust out pipe "F". (Scheme 26) Disconnect jumper wires. Air should not exhaust out pipe "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 appropriate «WIRING DIAGRAMS»(ref-21770) 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 TESTS»(ref-21745) article. Replace as necessary.

Scheme 26

1. Remove purge control 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 pipe "E" should exhaust out pipe "F". (Scheme 26) Disconnect jumper wires. Air should not exhaust out pipe "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. Turn ignition on. Using DVOM, backprobe harness connector. Measure voltage between ground and terminal No. 2 (Yellow/Black wire) at ECM E9 connector. see scheme 6 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 fuel evaporation system related vacuum hose connections. Repair as necessary. If hose connections are okay, check charcoal canister. See EMISSION SYSTEMS & SUB-SYSTEMS in appropriate «SYSTEM/COMPONENT TESTS»(ref-21745) article. Replace as necessary. If canister is okay, replace ECM and retest.

VSS outputs a 4-pulse signal for every revolution of the rotor shaft, which is driven by transaxle output shaft. Signal is used by ECM to determine vehicle speed. Code is set if there is no VSS signal to ECM while vehicle is being driven or if park/neutral switch is off. Possible causes are

1. Vehicle speed sensor.
2. Open or short circuit in VSS circuit.
3. Instrument cluster.
4. ECM malfunction.

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 «SYSTEM/COMPONENT TESTS»(ref-21745) article. Repair as necessary.
2. Access ECM behind glove box. Turn ignition off. Disconnect ECM E10 connector. see scheme 6 Using DVOM, check for continuity between ground and terminal No. 12 (Violet/Yellow wire) at ECM E10 connector. If continuity does not exist, go to next step. If continuity exists, locate and repair short to ground in Violet/Yellow wire between ECM and instrument cluster.
3. Measure voltage between ground and terminal No. 12 (Violet/Yellow wire) at ECM E10 connector. If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, locate and repair open in Violet/Yellow wire between junction block No. 3, located behind instrument cluster, and ECM.
4. Check for open in Violet/Yellow wire between junction block No. 3 and instrument cluster. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-21770) article. Repair wiring as necessary. If wiring is okay, replace ECM and retest.

Idle Air Control (IAC) valve is a rotary solenoid type and is located in front of air intake chamber. Intake air by-passing the throttle valve is directed to IAC valve through a passage. This allows air volume by-passing the throttle valve to be regulated. Code is set if idle speed continues to vary greatly from target speed. Possible causes are

1. IAC valve stuck or closed.
2. Open or short circuit in IAC valve circuit.
3. Vacuum Switching Valve (VSV) for A/C idle-up.
4. Air intake hose.

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. Check idle-up system. See MISCELLANEOUS CONTROLS in appropriate «SYSTEM/COMPONENT TESTS»(ref-21745) article. Repair as necessary. If idle-up system is okay, go to next step
3. Access ECM behind glove box. Turn ignition off. Disconnect ECM E7 connector. see scheme 6 Turn ignition on. Using DVOM, measure voltage between ground and terminals No. 22 (Yellow/Black wire) and No. 23 (Green/Black wire) at ECM E7 connector. If both readings are 9-14 volts, go to step 5). If any reading is not 9-14 volts, go to next step.
4. Disconnect IAC valve connector. Measure resistance between Black/Orange wire terminal and Green/Black and Yellow/Black wire terminals at IAC valve. Resistance should be 17-24 ohms (cold) or 21.5-28.5 ohms (hot). If both readings are as specified, check for open or short circuit in wiring harness between junction block No. 2, located in left side of engine compartment, and ECM. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-21770) article. If any readings is not as specified, replace IAC valve.
5. Check IAC valve. See IDLE CONTROL SYSTEM in appropriate «SYSTEM/COMPONENT TESTS»(ref-21745) article. Replace IAC valve as necessary. If IAC valve is okay, replace ECM and retest.

The TP sensor is variable resistor that monitors throttle opening. The ECM determines vehicle driving condition and adjusts air/fuel mixture accordingly. The CTP switch is located inside of TP sensor. If CTP switch is defective, TP sensor must be replaced. Code is set if CTP switch does not turn on when vehicle is driven. Possible causes are

1. Open in CTP switch circuit.
2. CTP switch malfunction.
3. ECM malfunction.

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 Brown wire and Blue/White wire at TP sensor harness connector. 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 TP sensor.
2. Access ECM behind glove box. Turn ignition off. Connect a jumper wire between terminals No. 32 (Blue/White wire) at ECM E7 connector and No. 22 (Brown wire) at ECM E8 connector. see scheme 6 Turn ignition on. Using scan tester, read CTP switch signal. If CTP switch signal is off, replace ECM. 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 Blue/White wire and Brown wire at TP sensor harness connector.
2. If voltage is not 9-14 volts, check for open circuit in Blue/White and Brown wires between ECM and TP sensor. Repair as necessary. If wiring is okay, replace ECM. If voltage is 9-14 volts, check TP sensor connector. Repair as necessary. If connector is okay, replace TP sensor and retest.

Ignitor keeps the ignition coil primary circuit grounded, allowing a magnetic field to be built up in the ignition coil. When the ECM signals the ignitor, the ignitor interrupts the primary circuit, causing the ignition coil to fire. Also, by the counter electromotive force generated when the primary current is interrupted, the ignitor sends an Ignition Confirmation Signal (IGF) to the ECM. If IGF signal is not input to ECM, the ECM will stop fuel injection as a fail safe function.

Code is set if there is no IGF signal to ECM for 6 consecutive ignition signals with engine running. Possible causes are

1. Open or short in IGF or IGT circuits.
2. Ignitor malfunction.
3. ECM malfunction.

Scheme 27

1. Disconnect Dark Gray 8-pin ignitor connector. Turn ignition on. Measure voltage between ground and terminal No. 1 at ignitor connector. (Scheme 27) 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»(ref-21770) article.
2. Measure voltage between ground and terminals No. 2-7. If each reading is 9-14 volts, go to step 4). If any reading is not 9-14 volts, go to next step.
3. Disconnect connector of ignition coil connected to terminal that did not have 9-14 volts in step 2). Measure resistance between ignition coil connector terminals. Resistance should be.54-.84 ohms (cold) or.68-.98 ohms (hot). If resistance is as not as specified, replace coil and retest. If resistance is as specified, check for open or short circuit in wiring harness between junction block No. 1, located at left side of instrument panel, and ECM. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-21770) article. Repair as necessary.
4. Disconnect Black 8-pin ignitor connector. Check for continuity between ground and terminal No. 7 (White/Black wire) at Black ignitor connector. If continuity exists, go to next step. If continuity does not exist, locate and repair open in White/Black wire between ground and ignitor connector.
5. Turn ignition on. Measure voltage between ground and terminal No. 8 (White/Red wire) at Black ignitor connector. If voltage is not 4.4-5.5 volts, check for open or short circuit in White/Red wire between ignitor and ECM. Repair as necessary. If wire is okay, replace ECM and retest. If voltage is 4.5-5.5 volts, check for open or short between each remaining wire (terminals No. 1-6) at Black ignitor connector and appropriate terminal at ECM. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-21770) article. Repair as necessary. If all wires are okay, go to next step.
6. Ensure Black ignitor connector is still disconnected. Access ECM behind glove box. Locate ECM E7 connector. see scheme 6 Backprobing ECM connector, measure voltage between ground and the following terminals at ECM E7 connector while cranking engine. ECM terminal No. 15 (Green/Black wire). ECM terminal No. 16 (Yellow/Red wire). ECM terminal No. 24 (White/Green wire). ECM terminal No. 26 (Blue/Black wire). ECM terminal No. 29 (Green/Red wire). ECM terminal No. 30 (Red/Black wire).

If all readings are 0.5-1.0 volt, replace ignitor and retest. If any reading is not 0.5-1.0 volt, replace ECM and retest.

When engine is being cranked, intake air flow is slow, so fuel vaporization is poor. A rich mixture is necessary to achieve good startability. While engine is being cranked, battery voltage is supplied to ECM terminal STA. Starter signal is mainly used to increase fuel injection pulse for starting injection control and after-start injection control. Code is set is there is no starter signal to ECM. Possible causes are

1. Open or short in starter signal circuit.
2. Open or short in ignition switch or starter relay circuit.
3. ECM malfunction.

1. Remove instrument panel fuse cover. Connect Lexus scan tester to Data Link Connector (DLC) No. 3. see scheme 6 Turn scan tester on. Turn ignition switch on. Using scan tester, read STA signal while cranking starter. With ignition switch in ON position, 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 detected at this time. Diagnose by symptom. See «TESTS W/O CODES»(ref-21769) 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»(ref-21770) article. Repair as necessary. If wiring is okay, replace ECM and retest.

Battery voltage is supplied to BATT terminal at ECM at all times. This circuit is used by diagnostic trouble code memory and air/fuel ratio adaptive control value memory. Code is set if there is an open in backup power source circuit. Possible causes are

1. Open in backup power source circuit.
2. ECM malfunction.

1. Access ECM behind glove box. Locate ECM E10 connector. see scheme 6 Backprobing ECM connector, measure voltage between ground and terminal No. 14 (White/Blue wire) at ECM E10 connector. 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 15-amp fuse 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.

Knock sensors are located on either side of cylinder block. Sensor generates voltage when engine block vibrates due to knocking. Code is set if there is a ECM malfunction for knock control. Possible cause is

1. ECM malfunction.

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

Park/neutral position switch is on whenever shift lever is in "N" or "P" position. With switch on, ECM terminal NSW is grounded via starter relay (zero voltage at terminal NSW). With shift lever in "D", "2", "L" or "R" position, switch is off (battery voltage at terminal NSW). Code is set under the following conditions

1. Two or more switches are on simultaneously for "N", "2" or "L" position.
2. If park/neutral switch is on while driving vehicle for 30 seconds or more at 44 MPH or more.
3. If park/neutral switch is on while driving vehicle for 30 seconds or more with engine speed at 1500-2500 RPM.

1. Check park/neutral position switch. See ENGINE SENSORS & SWITCHES in «SYSTEM/COMPONENT TESTS»(ref-21745) article. Replace switch as necessary. If switch is okay, go to next step.
2. Access ECM behind glove box. Turn ignition on. Measure voltage between ground and terminal No. 14 (Black/White wire) at ECM E7 connector. see scheme 6 With shift lever in "P" or "N" position, volt age 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 is wiring harness between ECM and park/neutral position switch. See appropriate wiring diagram in «WIRING DIAGRAMS»(ref-21770) article.