Engine Control System Self-Diagnostics: Diagnosis Toyota Avalon XX20

DIAGNOSTIC TROUBLE CODE DEFINITIONS

DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION

DIAGNOSTIC TESTS

Note. Before performing any diagnostic test, see SELF-DIAGNOSTICS - INTRODUCTION article for diagnostic system functions and system diagnostic procedures. For component location, see appropriate illustration in THEORY & OPERATION article. To identify circuits and wire colors referenced in testing, see WIRING DIAGRAMS article. To identify ECM terminals referenced in testing, see illustration. (Scheme 1)

Note. For information on engine immobilizer system, see COMPUTERIZED ENGINE CONTROLS in THEORY & OPERATION article.

Scheme 1

Diagnosis & Repair

1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 2) Start and warm engine to normal operating temperature. Using scan tool, monitor MAF flow rate. If scan tool reading is 0.0 gm/sec., go to next step. If scan tool reading is 271 gm/sec. or more, go to step 5.
2. Turn ignition off. Disconnect MAF meter harness connector. Turn ignition on. Measure voltage between ground and terminal No. 1 (Black/White wire) at MAF meter harness connector. (Scheme 3) If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, repair open in Black/White wire between EFI fuse No. 2 and MAF meter. See WIRING DIAGRAMS article.
3. Turn ignition off. Connect MAF meter harness connector. Access ECM behind passenger's side kick panel. Ensure shift lever is in Neutral or Park. Ensure A/C switch is off. Start engine and let idle. Using DVOM, backprobe ECM harness connector and measure voltage between ground and terminal No. 10 (Red wire) at ECM harness connector E5. (Scheme 1) If voltage is not 1.1-1.5 volts, go to next step. If voltage is 1.1-1.5 volts, replace ECM.
4. Check for open or short in Red wire between MAF meter and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace MAF meter.
5. Turn ignition off. Access ECM behind passenger's side kick panel. Using DVOM, backprobe ECM harness connector and measure resistance between ground and terminal No. 19 (Red/Black wire) at ECM harness connector E5. (Scheme 1) If resistance is one ohms or less, go to next step. If resistance is greater than one ohm, replace ECM.
6. Check for open in Red/Black wire between MAF meter and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace MAF meter.

Scheme 2

Scheme 3

Circuit Description

MAF meter uses a platinum hot wire maintained at a constant temperature. Airflow past sensor affects temperature and current flow through MAF meter. DTC is set when ECM detects either throttle valve is fully closed and MAF meter output is more than 2.2 volts for more than 10 seconds with engine speed of 900 RPM or less, or VTA circuit signal is .63 volt or more and MAF meter output is less than 1.06 volts for more than 10 seconds with engine speed of 1500 RPM or more. ECM will operate in fail-safe mode if DTC P0101 is set. Possible cause is

1. Defective MAF meter.

Diagnostic Aids

After confirming DTC P0101, use scan tool to access CURRENT DATA to confirm mass airflow ratio. If ratio is 0.0 gm/sec., VG circuit may be open or shorted, or power source circuit may be open. If ratio is 271.0 gm/sec. or more, E2G circuit may be open. Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.

If only DTC P0101 is displayed, replace MAF meter. If other DTCs are displayed, diagnose and repair those DTCs first and retest.

1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 2) Turn ignition on. Using scan tool, monitor IAT sensor temperature. If temperature displayed on scan tool is same as outside temperature, problem is intermittent. Check component and ECM connections. If temperature displayed on scan tool is -40°F (-40°C), go to next step. If temperature displayed on scan tool is 284°F (140°C) or more, go to step 4.
2. Turn ignition off. Disconnect MAF meter harness connector. Using a jumper wire, connect MAF meter harness connector terminals No. 4 (Blue/Black wire) and No. 5 (White wire). (Scheme 3) Turn ignition on. Using scan tool, monitor IAT sensor temperature. If temperature displayed on scan tool is 284°F (140°C) or more, replace MAF meter. If temperature displayed on scan tool is less than 284°F (140°C), go to next step.
3. Turn ignition off. Remove jumper wire. Access ECM behind passenger's side kick panel. Using a jumper wire, backprobe between terminals No. 18 (White wire) and No. 22 (Blue/Black wire) at ECM harness connector E5. (Scheme 1) If temperature displayed on scan tool is 284°F (140°C) or more, repair open in Blue/Black wire and/or White wire between MAF meter and ECM. See WIRING DIAGRAMS article. If temperature displayed on scan tool is less than 284°F (140°C), replace ECM.
4. Turn ignition off. Disconnect MAF meter harness connector. Turn ignition on. If temperature displayed on scan tool is -40°F (-40°C), replace MAF meter. If temperature displayed on scan tool is not -40°F (-40°C), go to next step.
5. Turn ignition off. Access ECM behind passenger's side kick panel. Disconnect ECM harness connector E5. (Scheme 1) Turn ignition on. If temperature displayed on scan tool is -40°F (-40°C), repair short in Blue/Black wire between MAF meter and ECM. See WIRING DIAGRAMS article. If temperature displayed on scan tool is not -40°F (-40°C), replace ECM.

1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 2) Turn ignition on. Using scan tool, monitor ECT sensor temperature. If temperature displayed on scan tool is same as actual coolant temperature, problem is intermittent. Check component and ECM connections. If temperature displayed on scan tool is -40°F (-40°C), go to next step. If temperature displayed on scan tool is 284°F (140°C) or more, go to step 4.
2. Turn ignition off. Disconnect ECT sensor harness connector (2-pin harness connector with Green/Yellow wire and White wire). ECT sensor is located in coolant housing in front of intake manifold on timing belt side of engine. Using a jumper wire, connect ECT sensor harness connector terminals. Turn ignition on. Using scan tool, monitor ECT sensor temperature. If temperature displayed on scan tool is less than 284°F (140°C), go to next step. If temperature displayed on scan tool is 284°F (140°C) or more, replace ECT sensor.
3. Turn ignition off. Remove jumper wire. Access ECM behind passenger's side kick panel. Using a jumper wire, backprobe between terminals No. 18 (White wire) and No. 14 (Green/Yellow wire) at ECM harness connector E5. (Scheme 1) If temperature displayed on scan tool is 284°F (140°C) or more, repair open in Green/Yellow wire and/or White wire between ECT sensor and ECM. See WIRING DIAGRAMS article. If temperature displayed on scan tool is less than 284°F (140°C), replace ECM.
4. Turn ignition off. Disconnect ECT sensor harness connector. Turn ignition on. If temperature displayed on scan tool is -40°F (-40°C), replace ECT sensor. If temperature displayed on scan tool is not -40°F (-40°C), go to next step.
5. Turn ignition off. Access ECM behind passenger's side kick panel. Disconnect ECM harness connector E5. (Scheme 1) Turn ignition on. If temperature displayed on scan tool is -40°F (-40°C), repair short in Green/Yellow wire between ECT sensor and ECM. See WIRING DIAGRAMS article. If temperature displayed on scan tool is not -40°F (-40°C), replace ECM.

1. If any other DTCs are displayed, diagnose and repair those DTCs first and retest. If only DTC P0116 is displayed, go to next step.
2. Remove and inspect cooling system thermostat. If problem exists, replace thermostat as necessary and retest. If problem does not exist, replace ECT sensor.

1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 2) Turn ignition on. Using scan tool, monitor throttle valve opening percentage. Opening percentage should be approximately 10 percent with fully closed throttle, and 75 percent with fully open throttle (WOT). If percentages are not as specified, go to next step. If percentages are as specified, problem may be intermittent. Check component and ECM connections.
2. Turn ignition off. Disconnect TP sensor harness connector. Turn ignition on. Measure voltage between ground and terminal No. 1 (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. Check TP sensor. See ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - V6 & V8 article. If sensor is defective, replace TP sensor. If sensor is okay, go to next step.
4. Connect TP sensor harness connector. Access ECM behind passenger's side kick panel. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 23 (Green wire) and No. 18 (White wire) at ECM harness connector E5. (Scheme 1) Voltage should be.3-1.0 volt with throttle fully closed, and 2.7-5.2 volts with throttle fully open (WOT). If voltages are as specified, replace ECM. If voltages are not as specified, repair open or short in Green wire between TP sensor and ECM. See WIRING DIAGRAMS article.
5. Access ECM behind passenger's side kick panel. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 2 (Blue/Red wire) and No. 18 (White wire) at ECM harness connector E5. (Scheme 1) If voltage is 4.5-5.5 volts, repair open in Blue/Red wire between TP sensor and ECM. See WIRING DIAGRAMS article. If voltage is not 4.5-5.5 volts, replace ECM.

TP sensor is a variable resistor mounted to throttle body, which detects throttle opening angle. ECM determines vehicle driving condition and adjusts air/fuel mixture accordingly. DTC is set after vehicle speed has exceeded 19 MPH once and TP sensor output voltage is out of range while vehicle speed is 0-19 MPH. Possible cause is

1. Defective Throttle Position (TP) sensor.

After confirming DTC P0121, use scan tool to access CURRENT DATA to confirm throttle valve opening percentage with throttle open and closed. If percentage displayed on scan tool is always zero percent, VC circuit may be open or VTA circuit may be shorted. If percentage displayed on scan tool is always 75 percent, check for open in E2 circuit. Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.

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

1. If other DTCs are displayed, diagnose and repair those DTCs first and retest system. If only DTC P0125 is displayed, go to next step.
2. Connect scan tool to Data Link Connector (DLC) No. 3. Start engine and increase engine speed to 2500 RPM for approximately 90 seconds. Using scan tool, monitor each A/F sensor output voltage. See «AIR/FUEL RATIO SENSOR VOLTAGE SPECIFICATIONS»(ref-2593-S15131677192000040700000) table. If voltage is as specified, go to next step. If voltage is not as specified, go to step 9. AIR/FUEL RATIO SENSOR VOLTAGE SPECIFICATIONS Application (1) Volts Using OBD-II Scan Tool Engine Idling 0.66 Engine Racing 0.76 Or More Driving Vehicle (2) 0.56 Or Less Using Toyota Hand-Held Tester Engine Idling 3.3 Engine Racing 3.8 Or More Driving Vehicle (2) 2.8 Or Less (1) Voltage should not remain constant at specification given. (2) Drive vehicle at 25 MPH or more, with engine speed at 1500 RPM or more, while opening and closing throttle valve.
3. Check for open or short in wiring between ECM and suspect A/F sensor. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
4. Disconnect suspect A/F sensor harness connector. A/F sensor for bank 2 is located in exhaust manifold. A/F sensor for bank 1 is located in exhaust pipe in front of catalytic converter. Measure resistance between terminals B+ (Black/White wire) and HT (Black/Red wire) at A/F sensor connector (component side). (Scheme 4) Resistance should be.8-1.4 ohms at 68°F (20°C) and 1.8-3.2 ohms at 1472°F (800°C). If resistances are not as specified, replace appropriate A/F sensor. If resistances are as specified, go to next step.
5. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, go to next step.
6. Check fuel pressure. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If fuel pressure is not within specification, repair as necessary. If fuel pressure is within specification, go to next step.
7. Check fuel injectors. See FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, repair as necessary. If problem does not exist, go to next step.
8. Check exhaust system for leaks. If problem exists, repair as necessary. If problem does not exist, replace defective A/F sensor.
9. Perform test drive confirmation, then go to next step. See «TEST DRIVE CONFIRMATION»(ref-2593-S18304561522000040700000) under DTC P1130 OR P1150: AIR/FUEL SENSOR CIRCUIT RANGE/PERFORMANCE.
10. Clear and recheck for DTCs. If DTC P0125 is displayed again, replace ECM. If DTC P0125 is not displayed again, go to next step.
11. Vehicle either ran out of fuel or problem is intermittent. Check component and ECM connections.

Scheme 4

1. Remove and inspect cooling system thermostat. If problem exists, replace thermostat as necessary and retest. If problem does not exist, go to next step.
2. If any other DTCs are displayed, diagnose and repair those DTCs first and retest. If only DTC P0128 is displayed, replace ECM.

1. If any other DTCs are displayed, diagnose and repair those DTCs first. If only DTC P0136 is displayed, go to next step.
2. Check for open or short in wiring between ECM and heated oxygen sensor No. 2. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
3. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 2) Start and warm engine to normal operating temperature. Monitor heated oxygen sensor No. 2 output voltage. Snap accelerate engine to about 4000 RPM 3 times. Voltage should fluctuate from less than.4 volt to.6 volt or more. If voltage is as specified, problem is intermittent. Check component and ECM connections. If voltage is not as specified, replace heated oxygen sensor No. 2.

1. Access ECM behind passenger's side kick panel. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between ground and terminal No. 9 (Green wire) at ECM harness connector E7. (Scheme 1) Voltage should be 9-14 volts. If voltage is as specified, replace ECM. If voltage is not as specified, go to next step.
2. Turn ignition off. Disconnect heated oxygen sensor No. 2 harness connector. Connector is located underneath carpet on passenger's side, near center console. It may be necessary to remove passenger's seat to access connector. Measure resistance between terminals HT (Green wire) and B+ (Black/White wire) at heated oxygen sensor No. 2 connector (component side). (Scheme 5) Resistance should be 11-16 ohms at 68°F (20°C) and 23-32 ohms at 1472°F (800°C). If resistance is not as specified, replace heated oxygen sensor No. 2. If resistance is as specified, go to next step.
3. Repair wiring between ECM and heated oxygen sensor No. 2, or between heated oxygen sensor No. 2 and EFI main relay. See WIRING DIAGRAMS article.

Scheme 5

1. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, go to next step.
2. Check fuel injectors. See FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, repair as necessary. If problem does not exist, go to next step.
3. Check Mass Airflow (MAF) meter and Engine Coolant Temperature (ECT) sensor. See ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, replace appropriate component. If problem does not exist, go to next step.
4. Check spark and ignition system. See IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If problem exists, repair as necessary. If problem does not exist, go to next step.
5. Check fuel pressure. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If fuel pressure is not within specification, repair as necessary. If fuel pressure is within specification, go to next step.
6. Check exhaust system for leaks. If problem exists, repair as necessary. If problem does not exist, go to next step.
7. Connect scan tool to Data Link Connector (DLC) No. 3. Start engine and increase engine speed to 2500 RPM for approximately 90 seconds. Using scan tool, monitor each A/F sensor output voltage. See «AIR/FUEL RATIO SENSOR VOLTAGE SPECIFICATIONS»(ref-2593-S37685715612000040700000) table. If voltage is not as specified, go to next step. If voltage is as specified, go to step 9 . AIR/FUEL RATIO SENSOR VOLTAGE SPECIFICATIONS Application (1) Volts Using OBD-II Scan Tool Engine Idling 0.66 Engine Racing 0.76 Or More Driving Vehicle (2) 0.56 Or Less Using Toyota Hand-Held Tester Engine Idling 3.3 Engine Racing 3.8 Or More Driving Vehicle (2) 2.8 Or Less (1) Voltage should not remain at specification given. (2) Drive vehicle at 25 MPH or more, with engine speed at 1500 RPM or more, while opening and closing throttle valve.
8. Check for open or short in wiring between ECM and A/F sensor. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace appropriate A/F sensor.
9. Perform test drive confirmation, then go to next step. See «TEST DRIVE CONFIRMATION»(ref-2593-S18304561522000040700000) under DTC P1130 OR P1150: AIR/FUEL SENSOR CIRCUIT RANGE/PERFORMANCE.
10. Clear and recheck for DTCs. If DTC P0171 and/or P0172 are displayed again, replace ECM. If neither DTC P0171 nor P0172 are displayed again, go to next step.
11. Vehicle either ran out of fuel or problem is intermittent. Check component and ECM connections.

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

1. Open or short in wiring.
2. Poor contact at ECM or component.
3. Disconnect, blocked or damaged vacuum hose(s).
4. Ignition system malfunction.
5. Defective fuel injector(s).
6. Improper fuel pressure.
7. Defective Mass Airflow (MAF) meter.
8. Defective Engine Coolant Temperature (ECT) sensor.
9. Improper engine compression.
10. Improper valve clearance.
11. Improper valve timing.
12. Defective ECM.

When 2 or more codes for misfiring cylinder are recorded repeatedly but no random misfire code is recorded, it indicates misfires were detected and recorded at different times. If misfire cannot be reproduced, reason may be because of driving with lack of fuel, improper fuel, fouled spark plug, etc. Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.

Test Drive Confirmation

1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 2) Record any DTCs and freeze frame data. Switch scan tool to CHECK mode (Toyota hand-held tester only). Drive vehicle several times with engine speed, load and its surrounding range shown with ENGINE SPD, CALC LOAD in freeze frame data or MISFIRE RPM and MISFIRE LOAD in scan tool data list.
2. Drive vehicle at specified engine speeds. See «DRIVING PATTERN»(ref-2593-S40819584502000040700000) table. Turn ignition off after symptom is simulated the first time, then repeat test drive again (OBD-II scan tool only). If a misfire is detected, a DTC will set and misfire will be indicated in freeze frame data. Turn ignition off and wait a minimum of 5 seconds. DRIVING PATTERN RPM (1) Minutes Idling 3 1/2 1000 3 2000 1 1/2 3000 1 (1) Minimum specification is given.

1. Check vacuum hoses for leaks, blockage and proper routing. See VACUUM DIAGRAMS article. Also, check wiring and connectors for damage or poor connections. If problem exists, repair as necessary and perform «TEST DRIVE CONFIRMATION»(ref-2593-S06154645542000040700000). If problem does not exist, go to next step.
2. Check spark and ignition system. See IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If problem exists, repair as necessary. If problem does not exist, go to next step.
3. Access ECM behind passenger's side kick panel. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between ground and fuel injector terminals at specified ECM harness connector. See «IDENTIFYING FUEL INJECTOR TERMINALS»(ref-2593-S32950307972000040700000) table. (Scheme 1) If voltage is 9-14 volts at each terminal, go to step 6. If voltage is not 9-14 volts at each terminal, go to next step. IDENTIFYING FUEL INJECTOR TERMINALS Fuel Injector No. ECM Terminal No. Wire Color 1 (1) 5 Blue 2 (1) 6 Red 3 (2) 1 Yellow 4 (2) 2 White 5 (2) 3 Green 6 (2) 4 Green (1) Terminal are located in ECM harness connector E5. (Scheme 1) (2) Terminals are located in ECM harness connector E4. (Scheme 1)
4. Disconnect fuel injector harness connector at misfiring cylinder. Measure resistance between fuel injector terminals (component side). Resistance should be 13.4-14.2 ohms at 68°F (20°C). If resistance is as specified, go to next step. If resistance is not as specified, replace fuel injector.
5. Check for open or short in wiring between ECM and fuel injector. See WIRING DIAGRAMS article. If problem exists, repair as necessary. If problem does not exist, repair open or short in fuel injector power source circuit. See WIRING DIAGRAMS article.
6. Check fuel pressure. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If fuel pressure is not within specification, repair as necessary. If fuel pressure is within specification, go to next step.
7. Check fuel injectors. See FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, repair as necessary. If problem does not exist, go to next step.
8. Check Mass Airflow (MAF) meter and Engine Coolant Temperature (ECT) sensor. See ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, replace appropriate component. If problem does not exist, go to next step.
9. Check engine compression. See BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If engine compression is okay, check valve clearance. See ON-VEHICLE ADJUSTMENTS - V6 & V8 article. If valve clearance is okay, it may be necessary to check valve timing. See appropriate article in ENGINES.

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

1. Open or short in wiring.
2. Poor contact at ECM or component.
3. Disconnect, blocked or damaged vacuum hose(s).
4. Ignition system malfunction.
5. Defective fuel injector(s).
6. Improper fuel pressure.
7. Defective Mass Airflow (MAF) meter.
8. Defective Engine Coolant Temperature (ECT) sensor.
9. Improper engine compression.
10. Improper valve clearance.
11. Improper valve timing.
12. Defective ECM.

When 2 or more codes for misfiring cylinder are recorded repeatedly but no random misfire code is recorded, it indicates misfires were detected and recorded at different times. If misfire cannot be reproduced, reason may be because of driving with lack of fuel, improper fuel, fouled spark plug, etc. Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.

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

1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 2) Disconnect EB1 connector. EB1 connector is an in-line harness connector near oil filler cap. EB1 connector is a 4-pin, Dark Gray connector. Remove, switch and install terminals No. 1 and 2 from male connector. (Scheme 6) Connect EB1 connector. Turn ignition on. Clear DTCs. Start and warm engine to normal operating temperature. Snap accelerate engine to about 4000 RPM 3 times. Retrieve DTCs. If same DTC is repeated, go to next step. If DTC changed, go to step 3.
2. Check for open or short in wiring between EB1 connector and ECM. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM. Ensure EB1 male connector terminals are returned to their original position.
3. Check for open or short in wiring between EB1 connector and knock sensor(s). To access harness, it may be necessary to remove intake manifold. See KNOCK SENSOR under ENGINE SENSORS & SWITCHES in REMOVAL & INSTALLATION - V6 & V8 article. If problem exists, repair wiring as necessary. If problem does not exist, replace knock sensor. Ensure EB1 male connector terminals are returned to their original position.

Scheme 6

1. Disconnect CKP sensor harness connector. Measure resistance between CKP sensor connector terminals (component side). Resistance should be 1630-2740 ohms (cold sensor) or 2065-3225 ohms (hot sensor). If resistance is not as specified, replace CKP sensor. If resistance is as specified, go to next step.
2. Check for open or short in wiring between ECM and CKP sensor. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, remove and inspect CKP sensor. Also inspect signal plate. Replace CKP sensor and/or signal plate as necessary. If both components are okay, replace ECM.

1. Disconnect CMP sensor harness connector. Measure resistance between CMP sensor connector terminals (component side). Resistance should be 835-1400 ohms (cold sensor) and 1060-1645 ohms (hot sensor). If resistance is as specified, go to next step. If resistance is not as specified, replace CMP sensor.
2. Check for open or short in wiring between ECM and CMP sensor. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
3. Remove and inspect CMP sensor. Also inspect signal plate. If problem exists, replace CMP sensor and/or signal plate as necessary. If problem does not exist, replace ECM.

1. If other DTCs are displayed, diagnose and repair those DTCs first and retest system. If only DTC P0420 is displayed, go to next step.
2. Check exhaust system for leaks. If problem exists, repair as necessary. If problem does not exist, go to next step.
3. Check A/F sensor circuits. See «DTC P0125: INSUFFICIENT COOLANT TEMPERATURE FOR CLOSED LOOP FUEL CONTROL»(ref-2593-S30089601332000040700000) . If problem exists, repair as necessary. If problem does not exist, go to next step.
4. Check heated oxygen sensor No. 2 circuits. See «DTC P0136: HEATED OXYGEN SENSOR NO. 2 CIRCUIT»(ref-2593-S06489649342000040700000) . If problem exists, repair as necessary. If problem does not exist, replace catalytic converter.

Note. If DTC P0441, P0446, P0450 or P0451 is output after DTC P0440 or P0442, perform appropriate test first before performing this test.

1. Check for cracks, deformations in fuel tank, charcoal canister and fuel tank filler pipe. Check for disconnected hoses and tubes around fuel tank and charcoal canister. If problem exists, repair as necessary. If problem does not exist, go to next step.
2. Check fuel cap. If fuel cap is not an OEM cap, replace cap with an OEM cap. If fuel cap is an OEM cap, go to next step.
3. Check if fuel cap is properly installed. If problem exists, install fuel cap properly. If fuel cap is properly installed, go to next step.
4. Check for damaged fuel cap and gasket. If problem exists, replace fuel cap with OEM cap. If problem does not exist, go to next step.
5. Remove fuel cap. Visually inspect fuel tank filler neck for damage. If problem exists, replace fuel tank filler neck as necessary. If problem does not exist, go to next step.
6. Check vacuum hoses between vapor pressure sensor and fuel tank, and between charcoal canister and pressure switching valve VSV. Check hoses for correct installation, looseness and damage. If problem exists, repair vacuum hoses as necessary. If problem does not exist, go to next step.
7. Check hose and tube between fuel tank and charcoal canister for correct installation and damage. If problem exists, repair as necessary. If problem does not exist, go to next step.
8. Check charcoal canister for damage. If problem exists, repair or replace as necessary. If problem does not exist, go to next step.
9. Access ECM behind passenger's side kick panel. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 2 (Blue/Red wire) and No. 18 (White wire) at ECM harness connector E5. (Scheme 1) If voltage is not 4.5-5.5 volts, replace ECM. If voltage is 4.5-5.5 volts, go to next step.
10. Using DVOM, backprobe ECM harness connector and measure voltage between terminal No. 17 (Pink wire) at ECM harness connector E8 and terminal No. 18 (White wire) at ECM harness connector E5. (Scheme 1) Disconnect vacuum hose from vapor pressure sensor. (Scheme 7) Vapor pressure sensor is mounted on charcoal canister. Connect a vacuum pump to vapor pressure sensor. Voltage should be 2.9-3.7 volts without vacuum applied and.5 volt or less with 1.8 in. Hg applied. If voltage is as specified, go to step 12. If voltage is not as specified, go to next step.
11. Check for an open or short in wiring between vapor pressure sensor and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace vapor pressure sensor.
12. Check fuel tank and fuel tank over fill valve. If problem exists, repair or replace fuel tank or fuel tank over fill valve as necessary. If problem does not exist, no fault is indicated at this time. Probable cause of DTC to set was an incorrectly installed fuel cap.

Scheme 7

1. Check for cracks, deformations in fuel tank, charcoal canister and fuel tank filler pipe. Check for disconnected hoses and tubes around fuel tank and charcoal canister. If problem exists, repair as necessary. If problem does not exist, go to next step.
2. Check fuel cap. If fuel cap is not an OEM cap, replace cap with an OEM cap. If fuel cap is an OEM cap, go to next step.
3. Check if fuel cap is properly installed. If problem exists, install fuel cap properly. If fuel cap is properly installed, go to next step.
4. Check for damaged fuel cap and gasket. If problem exists, replace fuel cap with OEM cap. If problem does not exist, go to next step.
5. Remove fuel cap. Visually inspect fuel tank filler neck for damage. If problem exists, replace fuel tank filler neck as necessary. If problem does not exist, go to next step.
6. Check vacuum hoses between vapor pressure sensor and fuel tank, and between charcoal canister and pressure switching valve VSV. Check hoses for correct installation, looseness and damage. If problem exists, repair vacuum hoses as necessary. If problem does not exist, go to next step.
7. Check hose and tube between fuel tank and charcoal canister for correct installation and damage. If problem exists, repair as necessary. If problem does not exist, go to next step.
8. Check all EVAP system electrical component connections. If problem exists, repair as necessary. If problem does not exist, go to next step.
9. Check vacuum hoses between charcoal canister and fuel tank, and between fuel filler neck and fuel tank. If problem exists, repair as necessary. If problem does not exist, go to next step.
10. Access ECM behind passenger's side kick panel. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 2 (Blue/Red wire) and No. 18 (White wire) at ECM harness connector E5. (Scheme 1) If voltage is not 4.5-5.5 volts, replace ECM. If voltage is 4.5-5.5 volts, go to next step.
11. Using DVOM, backprobe ECM harness connector and measure voltage between terminal No. 17 (Pink wire) at ECM harness connector E8 and terminal No. 18 (White wire) at ECM harness connector E5. (Scheme 1) Disconnect vacuum hose from vapor pressure sensor. (Scheme 7) Vapor pressure sensor is mounted on charcoal canister. Connect a vacuum pump to vapor pressure sensor. Voltage should be 2.9-3.7 volts without vacuum applied and.5 volt or less with 1.8 in. Hg applied. If voltage is as specified, go to step 13. If voltage is not as specified, go to next step.
12. Check for an open or short in wiring between vapor pressure sensor and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace vapor pressure sensor.
13. Disconnect EVAP VSV vacuum hoses. Turn ignition on. Access ECM behind passenger's side kick panel. Connect a jumper wire by backprobing between ground and terminal No. 7 (Black/Red wire) at ECM harness connector E5. (Scheme 1) With jumper wire connected, air applied to EVAP VSV port "E" should flow from port "F". (Scheme 8) Remove jumper wire. With jumper wire removed, air applied to EVAP VSV port "E" should not flow from port "F". If EVAP VSV functions as specified, go to step 16. If EVAP VSV does not function as specified, go to next step.
14. Check EVAP VSV operation. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If EVAP VSV is okay, go to next step. If EVAP VSV is not okay, replace EVAP VSV. Also clean vacuum hose between throttle body and EVAP VSV, and between EVAP VSV and charcoal canister, then check charcoal canister. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article.
15. Check for an open or short in wiring between EFI main relay and EVAP VSV, and between EVAP VSV and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.
16. Disconnect canister closed valve VSV vacuum hoses. Turn ignition on. Access ECM behind passenger's side kick panel. Connect a jumper wire by backprobing between ground and terminal No. 10 (Green wire) at ECM harness connector E8. (Scheme 1) With jumper wire connected, air applied to canister closed valve VSV port "E" should not flow from port "F". (Scheme 9) Remove jumper wire. With jumper wire removed, air applied to canister closed valve VSV port "E" should flow from port "F". If canister closed valve VSV does not function as specified, go to next step. If canister closed valve VSV functions as specified, go to step 19.
17. Check canister closed valve VSV. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If canister closed valve VSV is okay, go to next step. If canister closed valve VSV is defective, replace canister closed valve VSV and charcoal canister. Also clean vacuum hose between charcoal canister and canister closed valve VSV.
18. Check for an open or short in wiring between EFI main relay and canister closed valve VSV, and between canister closed valve VSV and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.
19. Disconnect pressure switching valve VSV vacuum hoses. Turn ignition on. Access ECM behind passenger's side kick panel. Connect a jumper wire by backprobing between ground and terminal No. 3 (Pink/Black wire) at ECM harness connector E7. (Scheme 1) With jumper wire connected, air applied to pressure switching valve VSV port "E" should flow from port "F". (Scheme 10) Remove jumper wire. With jumper wire removed, air applied to pressure switching valve VSV port "E" should not flow from port "F". If pressure switching valve VSV functions as specified, go to step 22. If pressure switching valve VSV does not function as specified, go to next step.
20. Check pressure switching valve VSV. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. If pressure switching valve VSV is defective, replace pressure switching valve VSV and charcoal canister. Also clean vacuum hose between charcoal canister and pressure switching valve VSV, and between pressure switching valve VSV and fuel tank. If pressure switching valve VSV is okay, go to next step.
21. Check for an open or short in wiring between EFI main relay and pressure switching valve VSV, and between pressure switching valve VSV and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.
22. Charcoal canister or fuel tank overfill check valve maybe defective. Check fuel evaporation system. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in appropriate SYSTEM & COMPONENT TESTING article. Repair as necessary. If no problem is indicated, replace ECM.

Scheme 8

Scheme 9

Scheme 10

1. Access ECM behind passenger's side kick panel. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 2 (Blue/Red wire) and No. 18 (White wire) at ECM harness connector E5. (Scheme 1) If voltage is not 4.5-5.5 volts, replace ECM. If voltage is 4.5-5.5 volts, go to next step.
2. Using DVOM, backprobe ECM harness connector and measure voltage between terminal No. 17 (Pink wire) at ECM harness connector E8 and terminal No. 18 (White wire) at ECM harness connector E5. (Scheme 1) Disconnect vacuum hose from vapor pressure sensor. (Scheme 7) Connect a vacuum pump to vapor pressure sensor. Voltage should be 2.9-3.7 volts without vacuum applied and.5 volt or less with 1.8 in. Hg applied. If voltage is as specified, replace ECM. If voltage is not as specified, go to next step.
3. Check for open or short in wiring between vapor pressure sensor and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace vapor pressure sensor.

1. Test drive vehicle and check operation of speedometer. If speedometer is not operating correctly, repair speedometer as necessary. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. If speedometer is operating correctly, go to next step.
2. Access ECM behind passenger's side kick panel. Ensure ignition is off. Disconnect ECM harness connector E7. Check continuity between ground and terminal No. 22 (Violet/White wire) at ECM harness connector E7. (Scheme 1) If continuity exists, locate and repair short to ground in Violet/White wire between instrument cluster and ECM. If continuity does not exist, go to next step.
3. Turn ignition on. Measure voltage between ground and terminal No. 22 (Violet/White wire) at ECM harness connector E7. If voltage is 9-14 volts, replace ECM. If voltage is not 9-14 volts, repair open in Violet/White wire between instrument cluster and ECM. See WIRING DIAGRAMS article.

Diagnosis & Repair (Using Toyota Hand-Held Tester)

1. Connect hand-held tester to Data Link Connector (DLC) No. 3. (Scheme 2) Start engine and warm to normal operating temperature. Turn all accessories off. Ensure A/C is off. Place transmission in Neutral. Note idle speed. Using hand-held tester, select ACTIVE TEST mode and switch TE1 on. Note engine RPM and compare RPM readings. If difference in engine speed is more than 100 RPM, go to step 8. If difference in engine speed is 100 RPM or less, go to next step.
2. Turn ignition off. Turn ignition on. Using hand-held tester, check IAC valve duty ratio. If duty ratio is 27-47 percent, go to next step. If duty ratio is not 27-47 percent, replace ECM.
3. Check operation of IAC valve. See IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If IAC valve does not operate properly, go to step 5. If IAC valve operates properly, go to next step.
4. Remove IAC valve from throttle body. Check IAC valve and passages for carbon build-up and blockage. If problem exists, repair or replace as necessary. If problem does not exist, go to step 8.
5. Turn ignition off. Disconnect IAC valve harness connector. Turn ignition on. Measure voltage between ground and terminal No. 2 (Black/White wire) at IAC valve harness connector. If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, repair power distribution circuit as necessary. See WIRING DIAGRAMS article.
6. Check for open in Brown wire between ground and terminal No. 3 at IAC valve harness connector. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
7. Check for open or short in Green/Black wire between terminal No. 1 at IAC valve harness connector and terminal No. 26 at ECM harness connector E4. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace IAC valve.
8. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, an open or short in A/C switch signal circuit may exist. Check A/C amplifier. See appropriate MANUAL or AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING. Repair as necessary.

Diagnosis & Repair (Using OBD-II Scan Tool)

1. Start engine and warm to normal operating temperature. Turn all accessories off. Ensure A/C is off. Shift transaxle lever into Neutral. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 2) Note engine RPM. Using a jumper wire, connect terminals TE1 and E1 at DLC No. 1 in engine compartment. (Scheme 11) Note engine RPM and compare RPM readings. If difference in engine speed is more than 100 RPM, go to step 9. If difference in engine speed is 100 RPM or less, go to next step.
2. Turn ignition off. Access ECM behind passenger's side kick panel. Using an oscilloscope, backprobe between ground and terminal No. 26 (Green/Black wire) at ECM harness connector E4. Start engine and let idle. Oscilloscope waveform should be as illustrated. (Scheme 12) If waveform is as shown, go to step 6. If waveform is not as shown, go to next step.
3. Turn ignition off. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between ground and terminal No. 26 (Green/Black wire) at ECM harness connector E4. (Scheme 1) If voltage is 9-14 volts, replace ECM. If voltage is not 9-14 volts, go to next step.
4. Turn ignition off. Disconnect IAC valve harness connector. Measure voltage between ground and terminal No. 2 (Black/White wire) at IAC valve harness connector. If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, repair IAC valve power distribution circuit. See WIRING DIAGRAMS article.
5. Check for open or short in Green/Black wire between terminal No. 1 at IAC valve harness connector and terminal No. 26 at ECM harness connector E4. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace IAC valve.
6. Check IAC valve operation. See IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, go to next step. If problem does not exist, go to step 8.
7. Check for open in Brown wire between ground and terminal No. 3 at IAC valve harness connector. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace IAC valve.
8. Remove IAC valve from throttle body. Check IAC valve and passages for carbon build-up and blockage. If problem exists, repair or replace as necessary. If problem does not exist, go to next step.
9. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, an open or short in A/C switch signal circuit may exist. Check A/C amplifier. See appropriate MANUAL or AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING. Repair as necessary.

Scheme 11

Scheme 12

1. If using OBD-II scan tool, go to step 3. If using Toyota hand-held tester, connect hand-held tester to Data Link Connector (DLC) No. 3. (Scheme 2) Switch scan tool to CHECK mode and go to next step.
2. Start and warm engine to normal operating temperature with all accessories off. Drive vehicle at 38-75 MPH and engine speed at 1600-3200 RPM for 3-5 minutes. Stop vehicle and allow to idle for one minute. If malfunction exists, MIL will illuminate.
3. Start and warm engine to normal operating temperature. Drive vehicle at 38-75 MPH and engine speed at 1600-3200 RPM for 3-5 minutes. Stop vehicle and allow to idle for one minute. Turn ignition off. Repeat driving and idle part of test. If malfunction exists, MIL will illuminate.

1. If other DTCs are displayed, diagnose and repair those DTCs first and retest system. If only DTC P1130 and/or P1150 is displayed, go to next step.
2. Connect scan tool to Data Link Connector (DLC) No. 3. Start engine and increase engine speed to 2500 RPM for approximately 90 seconds. Using scan tool, monitor each A/F sensor output voltage. See «AIR/FUEL RATIO SENSOR VOLTAGE SPECIFICATIONS»(ref-2593-S22815962582000040700000) table. If voltage is as specified, go to next step. If voltage is not as specified, go to step 8. AIR/FUEL RATIO SENSOR VOLTAGE SPECIFICATIONS Application (1) Volts Using OBD-II Scan Tool Engine Idling 0.66 Engine Racing 0.76 Or More Driving Vehicle (2) 0.56 Or Less Using Toyota Hand-Held Tester Engine Idling 3.3 Engine Racing 3.8 Or More Driving Vehicle (2) 2.8 Or Less (1) Voltage should not remain constant at specification given. (2) Drive vehicle at 25 MPH or more, with engine speed at 1500 RPM or more, while opening and closing throttle valve.
3. Check for open or short in wiring between ECM and suspect A/F sensor. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
4. Disconnect suspect A/F sensor harness connector. A/F sensor for bank 2 is located in exhaust manifold. A/F sensor for bank 1 is located in exhaust pipe in front of catalytic converter. Measure resistance between terminals B+ (Black/White wire) and HT (Black/Red wire) at A/F sensor connector (component side). (Scheme 4) Resistance should be.8-1.4 ohms at 68°F (20°C) and 1.8-3.2 ohms at 1472°F (800°C). If resistances are not as specified, replace appropriate A/F sensor. If resistances are as specified, go to next step.
5. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, go to next step.
6. Check fuel pressure. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If fuel pressure is not within specification, repair as necessary. If fuel pressure is within specification, go to next step.
7. Check fuel injectors. See FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, repair as necessary. If problem does not exist, replace defective A/F sensor.
8. Perform test drive confirmation then go to next step. See «TEST DRIVE CONFIRMATION»(ref-2593-S18304561522000040700000).
9. Clear and recheck for DTCs. If DTC P1130 and/or P1150 is displayed again, replace ECM. If neither DTC P1130 nor P1150 are not displayed again, go to next step.
10. Vehicle either ran out of fuel or problem is intermittent. Check component and ECM connections.

1. If using OBD-II scan tool, go to step 3. If using Toyota hand-held tester, connect hand-held tester to Data Link Connector (DLC) No. 3. (Scheme 2) Switch scan tool to CHECK mode and go to next step.
2. Start and warm engine to normal operating temperature with all accessories off. Drive vehicle at 38-75 MPH with engine speed at 1600-3200 RPM for 3-5 minutes. Stop vehicle and allow to idle for one minute. If malfunction exists, MIL will illuminate.
3. Start and warm engine to normal operating temperature. Drive vehicle at 38-75 MPH with engine speed at 1600-3200 RPM for 3-5 minutes. Stop vehicle and allow to idle for one minute. Turn ignition off. Repeat driving and idle part of test. If malfunction exists, MIL will illuminate.

1. If other DTCs are displayed, diagnose and repair those DTCs first and retest system. If only DTC P1133 and/or P1153 is displayed, go to next step.
2. Connect scan tool to Data Link Connector (DLC) No. 3. Start engine and increase engine speed to 2500 RPM for approximately 90 seconds. Using scan tool, monitor each A/F sensor output voltage. See «AIR/FUEL RATIO SENSOR VOLTAGE SPECIFICATIONS»(ref-2593-S38017019242000040700000) table. If voltage is as specified, go to next step. If voltage is not as specified, go to step 8. AIR/FUEL RATIO SENSOR VOLTAGE SPECIFICATIONS Application (1) Volts Using OBD-II Scan Tool Engine Idling 0.66 Engine Racing 0.76 Or More Driving Vehicle (2) 0.56 Or Less Using Toyota Hand-Held Tester Engine Idling 3.3 Engine Racing 3.8 Or More Driving Vehicle (2) 2.8 Or Less (1) Voltage should not remain constant at specification given. (2) Drive vehicle at 25 MPH or more, with engine speed at 1500 RPM or more, while opening and closing throttle valve.
3. Check for open or short in wiring between ECM and suspect A/F sensor. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
4. Disconnect suspect A/F sensor harness connector. A/F sensor for bank 2 is located in exhaust manifold. A/F sensor for bank 1 is located in exhaust pipe before catalytic converter. Measure resistance between terminals B+ (Black/White wire) and HT (Black/Red wire) at A/F sensor connector (component side). (Scheme 4) Resistance should be.8-1.4 ohms at 68°F (20°C) and 1.8-3.2 ohms at 1472°F (800°C). If resistances are not as specified, replace appropriate A/F sensor. If resistances are as specified, go to next step.
5. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, go to next step.
6. Check fuel pressure. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If fuel pressure is not within specification, repair as necessary. If fuel pressure is within specification, go to next step.
7. Check fuel injectors. See FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, repair as necessary. If problem does not exist, replace defective A/F sensor.
8. Perform test drive confirmation then go to next step. See «TEST DRIVE CONFIRMATION»(ref-2593-S15056222072000040700000).
9. Clear and recheck for DTCs. If DTC P1133 and/or P1153 is displayed again, replace ECM. If neither DTC P1133 nor P1153 is displayed again, go to next step.
10. Vehicle either ran out of fuel or problem is intermittent. Check component and ECM connections.

1. Access ECM behind passenger's side kick panel. Turn ignition on. Using DVOM, backprobe at ECM harness connector and measure voltage between ground and terminals No. 4 (Black/Red wire) and No. 3 (Black/Red wire) at ECM harness connector E5. (Scheme 1) If both voltages are 9-14 volts, replace ECM. If either voltage is not 9-14 volts, go to next step.
2. Disconnect suspect A/F sensor harness connector. A/F sensor for bank 2 is located in exhaust manifold. A/F sensor for bank 1 is located in exhaust pipe in front of catalytic converter. Measure resistance between terminals B+ (Black/White wire) and HT (Black/Red wire) at A/F sensor connector (component side). (Scheme 4) Resistance should be.8-1.4 ohms at 68°F (20°C) and 1.8-3.2 ohms at 1472°F (800°C). If resistances are not as specified, replace appropriate A/F sensor. If resistances are as specified, go to next step.
3. Check A/F relay. See MOTORS & RELAYS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, repair as necessary. If problem does not exist, go to next step.
4. Repair for open or short in wiring between A/F relay and A/F sensor, and/or between A/F sensor and ECM. See WIRING DIAGRAMS article.

1. Check for spark at misfiring cylinder. See IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If spark exists, go to next step. If spark does not exist, go to step 4.
2. Check for open or short in Black/Yellow wire between terminal No. 25 at ECM harness connector E4 and ignition coil/ignitor No. 1. Also, check for open or short in Gray wire between terminal No. 11 at ECM harness connector E4 and ignition coil/ignitor No. 1. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
3. Disconnect ignition coil/ignitor No. 1 harness connector. Access ECM behind passenger's side kick panel. Turn ignition on. Using DVOM, backprobe at ECM harness connector and measure voltage between ground and terminal No. 25 (Black/Yellow wire) at ECM harness connector E4. (Scheme 1) If voltage is 4.5-5.5 volts, replace ignition coil/ignitor No. 1. If voltage is not 4.5-5.5 volts, replace ECM.
4. Check for open or short in Gray wire between terminal No. 11 at ECM harness connector E4 and ignition coil/ignitor No. 1. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
5. Access ECM behind passenger's side kick panel. Using DVOM, backprobe ECM harness connector and measure voltage between ground and terminal No. 11 (Gray wire) at ECM harness connector E4 while cranking engine. (Scheme 1) If voltage is.1-4.5 volts, go to next step. If voltage is not.1-4.5 volts, replace ECM.
6. Disconnect ignition coil/ignitor No. 1 harness connector. Using DVOM, backprobe ECM harness connector and measure voltage between ground and terminal No. 11 (Gray wire) at ECM harness connector E4 while cranking engine. If voltage is.1-4.5 volts, go to next step. If voltage is not.1-4.5 volts, replace ECM.
7. Turn ignition on. Measure voltage between ground and terminal No. 1 (Black/White wire) at ignition coil/ignitor No. 1 harness connector. (Scheme 13) If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, check and repair ignition coil/ignitor No. 1 power source circuit. See WIRING DIAGRAMS article.
8. Check for open or short in wiring between ground and terminal No. 4 (White/Black wire) at ignition coil/ignitor No. 1 harness connector. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace ignition coil/ignitor No. 1.

Scheme 13

1. Check for spark at misfiring cylinder. See IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If spark exists, go to next step. If spark does not exist, go to step 4.
2. Check for open or short in Black/Yellow wire between terminal No. 25 at ECM harness connector E4 and ignition coil/ignitor No. 2. Also, check for open or short in Black/Red wire between terminal No. 12 at ECM harness connector E4 and ignition coil/ignitor No. 2. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
3. Disconnect ignition coil/ignitor No. 2 harness connector. Access ECM behind passenger's side kick panel. Turn ignition on. Using DVOM, backprobe at ECM harness connector and measure voltage between ground and terminal No. 25 (Black/Yellow wire) at ECM harness connector E4. (Scheme 1) If voltage is 4.5-5.5 volts, replace ignition coil/ignitor No. 2. If voltage is not 4.5-5.5 volts, replace ECM.
4. Check for open or short in Black/Red wire between terminal No. 12 at ECM harness connector E4 and ignition coil/ignitor No. 2. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
5. Access ECM behind passenger's side kick panel. Using DVOM, backprobe ECM harness connector and measure voltage between ground and terminal No. 12 (Black/Red wire) at ECM harness connector E4 while cranking engine. (Scheme 1) If voltage is.1-4.5 volts, go to next step. If voltage is not.1-4.5 volts, replace ECM.
6. Disconnect ignition coil/ignitor No. 2 harness connector. Using DVOM, backprobe ECM harness connector and measure voltage between ground and terminal No. 12 (Black/Red wire) at ECM harness connector E4 while cranking engine. If voltage is.1-4.5 volts, go to next step. If voltage is not.1-4.5 volts, replace ECM.
7. Turn ignition on. Measure voltage between ground and terminal No. 1 (Black/White wire) at ignition coil/ignitor No. 2 harness connector. (Scheme 13) If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, check and repair ignition coil/ignitor No. 2 power source circuit. See WIRING DIAGRAMS article.
8. Check for open or short in wiring between ground and terminal No. 4 (White/Black wire) at ignition coil/ignitor No. 2 harness connector. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace ignition coil/ignitor No. 2.

1. Check for spark at misfiring cylinder. See IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If spark exists, go to next step. If spark does not exist, go to step 4.
2. Check for open or short in Black/Yellow wire between terminal No. 25 at ECM harness connector E4 and ignition coil/ignitor No. 3. Also, check for open or short in Light Green/Black wire between terminal No. 13 at ECM harness connector E4 and ignition coil/ignitor No. 3. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
3. Disconnect ignition coil/ignitor No. 3 harness connector. Access ECM behind passenger's side kick panel. Turn ignition on. Using DVOM, backprobe at ECM harness connector and measure voltage between ground and terminal No. 25 (Black/Yellow wire) at ECM harness connector E4. (Scheme 1) If voltage is 4.5-5.5 volts, replace ignition coil/ignitor No. 3. If voltage is not 4.5-5.5 volts, replace ECM.
4. Check for open or short in Light Green/Black wire between terminal No. 13 at ECM harness connector E4 and ignition coil/ignitor No. 3. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
5. Access ECM behind passenger's side kick panel. Using DVOM, backprobe ECM harness connector and measure voltage between ground and terminal No. 13 (Light Green/Black wire) at ECM harness connector E4 while cranking engine. (Scheme 1) If voltage is.1-4.5 volts, go to next step. If voltage is not.1-4.5 volts, replace ECM.
6. Disconnect ignition coil/ignitor No. 3 harness connector. Using DVOM, backprobe ECM harness connector and measure voltage between ground and terminal No. 13 (Light Green/Black wire) at ECM harness connector E4 while cranking engine. If voltage is.1-4.5 volts, go to next step. If voltage is not.1-4.5 volts, replace ECM.
7. Turn ignition on. Measure voltage between ground and terminal No. 1 (Black/White wire) at ignition coil/ignitor No. 3 harness connector. (Scheme 13) If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, check and repair ignition coil/ignitor No. 3 power source circuit. See WIRING DIAGRAMS article.
8. Check for open or short in wiring between ground and terminal No. 4 (White/Black wire) at ignition coil/ignitor No. 3 harness connector. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace ignition coil/ignitor No. 3.

1. Check for spark at misfiring cylinder. See IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If spark exists, go to next step. If spark does not exist, go to step 4.
2. Check for open or short in Black/Yellow wire between terminal No. 25 at ECM harness connector E4 and ignition coil/ignitor No. 4. Also, check for open or short in Light Green/Black wire between terminal No. 14 at ECM harness connector E4 and ignition coil/ignitor No. 4. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
3. Disconnect ignition coil/ignitor No. 4 harness connector. Access ECM behind passenger's side kick panel. Turn ignition on. Using DVOM, backprobe at ECM harness connector and measure voltage between ground and terminal No. 25 (Black/Yellow wire) at ECM harness connector E4. (Scheme 1) If voltage is 4.5-5.5 volts, replace ignition coil/ignitor No. 4. If voltage is not 4.5-5.5 volts, replace ECM.
4. Check for open or short in Blue/Yellow wire between terminal No. 14 at ECM harness connector E4 and ignition coil/ignitor No. 4. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
5. Access ECM behind passenger's side kick panel. Using DVOM, backprobe ECM harness connector and measure voltage between ground and terminal No. 14 (Blue/Yellow wire) at ECM harness connector E4 while cranking engine. (Scheme 1) If voltage is.1-4.5 volts, go to next step. If voltage is not.1-4.5 volts, replace ECM.
6. Disconnect ignition coil/ignitor No. 4 harness connector. Using DVOM, backprobe ECM harness connector and measure voltage between ground and terminal No. 14 (Blue/Yellow wire) at ECM harness connector E4 while cranking engine. If voltage is.1-4.5 volts, go to next step. If voltage is not.1-4.5 volts, replace ECM.
7. Turn ignition on. Measure voltage between ground and terminal No. 1 (Black/White wire) at ignition coil/ignitor No. 4 harness connector. (Scheme 13) If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, check and repair ignition coil/ignitor No. 4 power source circuit. See WIRING DIAGRAMS article.
8. Check for open or short in wiring between ground and terminal No. 4 (White/Black wire) at ignition coil/ignitor No. 4 harness connector. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace ignition coil/ignitor No. 4.

1. Check for spark at misfiring cylinder. See IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If spark exists, go to next step. If spark does not exist, go to step 4.
2. Check for open or short in Black/Yellow wire between terminal No. 25 at ECM harness connector E4 and ignition coil/ignitor No. 5. Also, check for open or short in Blue wire between terminal No. 15 at ECM harness connector E4 and ignition coil/ignitor No. 5. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
3. Disconnect ignition coil/ignitor No. 5 harness connector. Access ECM behind passenger's side kick panel. Turn ignition on. Using DVOM, backprobe at ECM harness connector and measure voltage between ground and terminal No. 25 (Black/Yellow wire) at ECM harness connector E4. (Scheme 1) If voltage is 4.5-5.5 volts, replace ignition coil/ignitor No. 5. If voltage is not 4.5-5.5 volts, replace ECM.
4. Check for open or short in Blue wire between terminal No. 15 at ECM harness connector E4 and ignition coil/ignitor No. 5. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
5. Access ECM behind passenger's side kick panel. Using DVOM, backprobe ECM harness connector and measure voltage between ground and terminal No. 15 (Blue wire) at ECM harness connector E4 while cranking engine. (Scheme 1) If voltage is.1-4.5 volts, go to next step. If voltage is not.1-4.5 volts, replace ECM.
6. Disconnect ignition coil/ignitor No. 5 harness connector. Using DVOM, backprobe ECM harness connector and measure voltage between ground and terminal No. 15 (Blue wire) at ECM harness connector E4 while cranking engine. If voltage is.1-4.5 volts, go to next step. If voltage is not.1-4.5 volts, replace ECM.
7. Turn ignition on. Measure voltage between ground and terminal No. 1 (Black/White wire) at ignition coil/ignitor No. 5 harness connector. (Scheme 13) If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, check and repair ignition coil/ignitor No. 5 power source circuit. See WIRING DIAGRAMS article.
8. Check for open or short in wiring between ground and terminal No. 4 (White/Black wire) at ignition coil/ignitor No. 5 harness connector. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace ignition coil/ignitor No. 5.

1. Check for spark at misfiring cylinder. See IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If spark exists, go to next step. If spark does not exist, go to step 4.
2. Check for open or short in Black/Yellow wire between terminal No. 25 at ECM harness connector E4 and ignition coil/ignitor No. 6. Also, check for open or short in Light Green wire between terminal No. 16 at ECM harness connector E4 and ignition coil/ignitor No. 6. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
3. Disconnect ignition coil/ignitor No. 6 harness connector. Access ECM behind passenger's side kick panel. Turn ignition on. Using DVOM, backprobe at ECM harness connector and measure voltage between ground and terminal No. 25 (Black/Yellow wire) at ECM harness connector E4. (Scheme 1) If voltage is 4.5-5.5 volts, replace ignition coil/ignitor No. 6. If voltage is not 4.5-5.5 volts, replace ECM.
4. Check for open or short in Light Green wire between terminal No. 16 at ECM harness connector E4 and ignition coil/ignitor No. 6. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
5. Access ECM behind passenger's side kick panel. Using DVOM, backprobe ECM harness connector and measure voltage between ground and terminal No. 16 (Light Green wire) at ECM harness connector E4 while cranking engine. (Scheme 1) If voltage is.1-4.5 volts, go to next step. If voltage is not.1-4.5 volts, replace ECM.
6. Disconnect ignition coil/ignitor No. 6 harness connector. Using DVOM, backprobe ECM harness connector and measure voltage between ground and terminal No. 16 (Light Green wire) at ECM harness connector E4 while cranking engine. If voltage is.1-4.5 volts, go to next step. If voltage is not.1-4.5 volts, replace ECM.
7. Turn ignition on. Measure voltage between ground and terminal No. 1 (Black/White wire) at ignition coil/ignitor No. 6 harness connector. (Scheme 13) If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, check and repair ignition coil/ignitor No. 6 power source circuit. See WIRING DIAGRAMS article.
8. Check for open or short in wiring between ground and terminal No. 4 (White/Black wire) at ignition coil/ignitor No. 6 harness connector. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace ignition coil/ignitor No. 6.

1. Disconnect suspect VVT sensor connector. Measure resistance between VVT sensor harness connector terminals. Resistance should be 835-1400 ohms at 14-122°F (cold sensor) and 1060-1645 ohms at 122-212°F (hot sensor). If resistance is not as specified, replace VVT sensor. If resistance is as specified, go to next step.
2. Check for open or short in wiring between ECM and appropriate VVT sensor. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
3. Remove and inspect VVT sensor. Also inspect signal plate. If problem exists, replace VVT sensor and/or signal plate as necessary. If problem does not exist, replace ECM.

Check valve timing. Check for loose, stretched or jumped teeth of timing belt. See appropriate article in ENGINES. If problem exists, repair as necessary. If problem does not exist, replace ECM.

1. Check valve timing. See appropriate article in ENGINES. If problem exists, repair as necessary. If problem does not exist, go to next step.
2. Connect hand-held tester to Data Link Connector (DLC) NO. 3. (Scheme 2) Using hand-held tester, select ACTIVE TEST mode. Select VVT. Note idle speed when OCV is activated by hand-held tester. If idle speed is normal with OCV off and engine idles rough or stalls when OCV is on, VVT is functioning properly at this time. DTC may have been set because of a foreign object that was temporarily caught in the engine oil system but after a short time system returned to normal. If idle speed does not function as specified, go to next step.
3. Access ECM behind passenger's side kick panel. Using oscilloscope, backprobe ECM harness connector. If checking OCV for bank No. 1 (right cylinder head), connect oscilloscope between terminals No. 18 (Red/White wire) and No. 29 (Red/Blue wire) at ECM harness connector E4. (Scheme 1) If checking OCV for bank No. 2 (left cylinder head), connect oscilloscope between terminals No. 5 (Red wire) and No. 6 (Red/Black wire) at ECM harness connector E4. On all applications, start engine and let idle. Ensure oscilloscope pattern is as shown in illustration. (Scheme 14) As engine speed is increased, waveform frequency ("A") should lengthen. If waveform pattern is as shown, go to next step. If waveform pattern is not as shown, replace ECM.
4. Remove timing belt cover and timing belt. See appropriate article in ENGINES. Remove valve cover. Remove OCV. Place a shop towel under OCV cylinder head opening. Rotate VVT pulley from left to right about 30 degrees 2-3 times. Oil should drain from OCV cylinder head opening. If oil does not drain from opening, replace VVT pulley/gear assembly and go to next step. If oil drains from opening, go to next step.
5. With OCV removed, connect a fused jumper wire between positive battery terminal and terminal No. 1 at OCV. (Scheme 15) Connect another jumper wire between negative battery terminal and terminal No. 2 at OCV and note OCV plunger operation. With battery voltage applied, plunger on end of OCV should extend. Disconnect a jumper wire. Without battery voltage applied, plunger should retract. If OCV operates as specified, go to next step. If OCV does not operate as specified, replace OCV and go to next step.
6. Check blockage in OCV. Check oil check valve and oil pipe located under OCV. If problem exists, repair as necessary. If problem does not exist, go to next step.
7. Install all remove components and connect all disconnected harness connectors. Using hand-held tester, clear DTCs. Start engine and allow it to idle. Turn ignition off. Turn ignition on and check for DTCs. If DTC P1349 or P1354 is not present, no problem is indicated at this time. DTC may have been set because of a foreign object that was temporarily caught in the engine oil system but after a short time system returned to normal. If DTC P1349 or P1354 is present, replace ECM.

Scheme 14

Scheme 15

1. Check valve timing. See appropriate article in ENGINES. If problem exists, repair as necessary. If problem does not exist, go to next step.
2. Start engine and allow it to idle. Disconnect suspect Oil Control Valve (OCV) and note idle speed. OCV is located in each cylinder head, underneath lower intake manifold. Engine idle speed should not change. Using jumper wires, apply battery voltage to OCV. Engine should idle rough or stall. If OCV operates as specified, go to next step. If OCV does not operate as specified, go to step 4.
3. Access ECM behind passenger's side kick panel. Using oscilloscope, backprobe ECM harness connector. If checking OCV for bank No. 1 (right cylinder head), connect oscilloscope between terminals No. 18 (Red/White wire) and No. 29 (Red/Blue wire) at ECM harness connector E4. (Scheme 1) If checking OCV for bank No. 2 (left cylinder head), connect oscilloscope between terminals No. 5 (Red wire) and No. 6 (Red/Black wire) at ECM harness connector E4. On all applications, start engine and let idle. Ensure oscilloscope pattern is as shown in illustration. (Scheme 14) As engine speed is increased, waveform frequency ("A") should lengthen. If waveform pattern is as shown, go to next step. If waveform pattern is not as shown, replace ECM.
4. Remove timing belt cover and timing belt. See appropriate article in ENGINES. Remove valve cover. Remove OCV. Place a shop towel under OCV cylinder head opening. Rotate VVT pulley from left to right about 30 degrees 2-3 times. Oil should drain from OCV cylinder head opening. If oil does not drain from opening, replace VVT pulley/gear assembly and go to next step. If oil drains from opening, go to next step.
5. With OCV removed, connect a fused jumper wire between positive battery terminal and terminal No. 1 at OCV. (Scheme 15) Connect another jumper wire between negative battery terminal and terminal No. 2 at OCV and note OCV plunger operation. With battery voltage applied, plunger on end of OCV should extend. Disconnect a jumper wire. Without battery voltage applied, plunger should retract. If OCV operates as specified, go to next step. If OCV does not operate as specified, replace OCV and go to next step.
6. Check blockage in OCV. Check oil check valve and oil pipe located under OCV. If problem exists, repair as necessary. If problem does not exist, go to next step.
7. Install and connect all disconnected harness connectors. Using hand-held tester, clear DTCs. Start engine and allow it to idle. Turn ignition off. Turn ignition on and check for DTCs. If DTC P1349 or P1354 is not present, no problem is indicated at this time. DTC may have been set because of a foreign object that was temporarily caught in the engine oil system but after a short time system returned to normal. If DTC P1349 or P1354 is present, replace ECM.

1. Check stoplight operation. If stoplights do not operate properly, repair as necessary and retest system. See appropriate wiring diagram in EXTERIOR LIGHTS article in ACCESSORIES & EQUIPMENT. If stoplights operate properly, go to next step.
2. Access ECM behind passenger's side kick panel. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between ground and terminal No. 15 (Red/Blue wire) at ECM harness connector E8. (Scheme 1) Voltage should be 7.5-14.0 volts with brake pedal depressed, and less than 1.5 volts with brake pedal released. If voltage is not as specified, go to next step. If voltage is as specified, problem is intermittent. Check component and ECM connections.
3. Check for short in wiring between ECM and stoplight switch. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.

1. Turn ignition off. Access ECM behind passenger's side kick panel. Using DVOM, backprobe ECM harness connector and measure voltage between ground and terminal No. 1 (Black/Red wire) at ECM harness connector E8. (Scheme 1) If voltage is 9-14 volts, replace ECM. If voltage is not 9-14 volts, go to next step.
2. Remove and inspect EFI fuse No. 1 (15-amp). EFI fuse is located in engine compartment junction block on left side of engine compartment. If fuse is blown, check for short to ground in wiring between EFI fuse No. 1 and ECM. See WIRING DIAGRAMS article. Repair as necessary and replace fuse. If fuse is okay, check for open in wiring between EFI fuse and ECM. Repair as necessary.

Note. Variable Valve Timing (VVT) sensor may also be referred to as camshaft position sensor.

Note. Bank No. 1 refers to bank which includes cylinder No. 1. Bank No. 2 refers to bank without cylinder No. 1.

The Variable Valve Timing (VVT) system controls intake valve timing in response to driving conditions. Electronic Control Module (ECM) controls Oil Control Valve (OCV) to ensure correct valve timing. A OCV is located in each cylinder head at flywheel side of engine. Oil pressure controlled by the OCV is supplied to the VVT controller. VVT controller then changes relative position between camshaft and crankshaft. VVT controller is located on the front of each intake camshaft. DTC P1656 or P1663 is set if ECM detects an open or short in OCV circuit. DTC P1656 is for bank No. 1 (right cylinder head) OCV circuit. DTC P1663 is for bank No. 2 (left cylinder head) OCV circuit. Possible causes are

1. OCV circuit is open or shorted.
2. Defective OCV.
3. Defective ECM.

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

1. Connect hand-held tester to Data Link Connector (DLC) NO. 3. (Scheme 2) Using hand-held tester, select ACTIVE TEST mode. Select VVT. Note idle speed when OCV is activated by hand-held tester. If idle speed is normal with OCV off and engine idles rough or stalls when OCV is on, VVT is functioning properly at this time. DTC may have been set because of a foreign object that was temporarily caught in the engine oil system but after a short time system returned to normal. If idle speed does not function as specified, go to next step.
2. Start engine and allow it to idle. Disconnect suspect Oil Control Valve (OCV) and note idle speed. OCV is located in each cylinder head underneath lower intake manifold. Engine idle speed should not change. Using jumper wires, apply battery voltage to OCV. Engine should idle rough or stall. If OCV operates as specified, go to next step. If OCV does not operate as specified, replace OCV.
3. Access ECM behind passenger's side kick panel. Using oscilloscope, backprobe ECM harness connector. If checking OCV for bank No. 1 (right cylinder head), connect oscilloscope between terminals No. 18 (Red/White wire) and No. 29 (Red/Blue wire) at ECM harness connector E4. (Scheme 1) If checking OCV for bank No. 2 (left cylinder head), connect oscilloscope between terminals No. 5 (Red wire) and No. 6 (Red/Black wire) at ECM harness connector E4. On all applications, start engine and let idle. Ensure oscilloscope pattern is as shown in illustration. (Scheme 14) As engine speed is increased, waveform frequency ("A") should lengthen. If waveform pattern is as shown, go to next step. If waveform pattern is not as shown, replace ECM.
4. Check for an open or short in wiring between suspect OCV and ECM. If problem exists, repair wiring as necessary. If problem does not exist, problem is intermittent. Check component and ECM connections.

1. Start engine and allow it to idle. Disconnect suspect Oil Control Valve (OCV) and note idle speed. OCV is located in each cylinder head, underneath lower intake manifold. Engine idle speed should not change. Using jumper wires, apply battery voltage to OCV. Engine should idle rough or stall. If OCV operates as specified, go to next step. If OCV does not operate as specified, replace OCV.
2. Access ECM behind passenger's side kick panel. Using oscilloscope, backprobe ECM harness connector. If checking OCV for bank No. 1 (right cylinder head), connect oscilloscope between terminals No. 18 (Red/White wire) and No. 29 (Red/Blue wire) at ECM harness connector E4. (Scheme 1) If checking OCV for bank No. 2 (left cylinder head), connect oscilloscope between terminals No. 5 (Red wire) and No. 6 (Red/Black wire) at ECM harness connector E4. On all applications, start engine and let idle. Ensure oscilloscope pattern is as shown in illustration. (Scheme 14) As engine speed is increased, waveform frequency ("A") should lengthen. If waveform pattern is as shown, go to next step. If waveform pattern is not as shown, replace ECM.
3. Check for an open or short in wiring between suspect OCV and ECM. If problem exists, repair wiring as necessary. If problem does not exist, problem is intermittent. Check component and ECM connections.

Note. Toyota hand-held tester can be used to confirm PNP switch signal from CURRENT DATA.

1. Access ECM behind passenger's side kick panel. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between ground and specified terminal at appropriate ECM harness connector with shift lever in appropriate position. See «PARK/NEUTRAL POSITION SWITCH VOLTAGE»(ref-2593-S25530968002000040700000) table. (Scheme 1) If voltage is as specified, replace ECM. If voltage is not as specified, go to next step. PARK/NEUTRAL POSITION SWITCH VOLTAGE Shift Lever Position ECM Terminal No. Volts Park & Neutral 8 (1) Zero 13 (1) Zero 14 (1) Zero 20 (2) Zero Reverse 8 (1) (3) 9-14 13 (1) Zero 14 (1) Zero 20 (2) (3) 9-14 Drive 8 (1) Zero 13 (1) Zero 14 (1) Zero 20 (2) 9-14 2 8 (1) Zero 13 (1) Zero 14 (1) 9-14 20 (2) 9-14 Low 8 (1) Zero 13 (1) 9-14 14 (1) Zero 20 (2) 9-14 (1) Terminal located at ECM harness connector E6. (Scheme 1) (2) Terminal located at ECM harness connector E7. (Scheme 1) (3) Voltage may be slightly less due to lighting of reverse lights.
2. Disconnect PNP switch harness connector. Check continuity between appropriate PNP switch terminals (component side) with shift lever in appropriate position. See «PARK/NEUTRAL POSITION SWITCH CONTINUITY»(ref-2593-S16204498452000040700000) table. (Scheme 16) If problem exists, replace PNP switch. If problem does not exist, go to next step. PARK/NEUTRAL POSITION SWITCH CONTINUITY Shift Lever Position Continuity Between Terminals No. Park 2 & 7; 5 & 6 Reverse 2 & 8 Neutral 2 & 9; 5 & 6 Drive 2 & 10 2 2 & 3 Low 2 & 4
3. Check wiring between battery and PNP switch and between PNP switch and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.

Scheme 16