Circuit Description

The crankshaft position sensor (NE signal) consists of a magnet, iron core and pickup coil. The NE signal plate (crankshaft position sensor plate) has 34 teeth and is installed on the crankshaft. The NE signal sensor generates 34 signals at every engine revolution. The ECM detects the crankshaft angle and the engine revolution based on the NE signal, and the cylinder and the angle of the VVT based on the combination of the VV and NE signal.

Note. Read freeze frame data using the hand-held tester or the OBD II scan tool, as freeze frame data records the engine conditions when a malfunction is detected.

For location of camshaft timing gear (Scheme 751)

Check valve timing. See appropriate article in ENGINES. Check for timing gears and/or chain damage. Repair if necessary. If no timing gear and/or chain damage is present, replace ECM. Engine Control Module (ECM) is located behind glove box. see scheme 7

Read freeze frame data using the hand-held tester or the OBD II scan tool, as freeze frame data records the engine conditions when a malfunction is detected.

For circuit wiring diagram, diagnosis and repair procedure (Scheme 697)& (Scheme 698).

For ECM location see scheme 7 For ECM connector view (Scheme 687) For testing of systems or components, see SYSTEM & COMPONENT TESTING - V6 & V8 article. For removal and installation of components, see REMOVAL & INSTALLATION - V6 & V8 article.

Scheme 697

Scheme 697: Diagnosis & Repair

Scheme 698

Note. Read freeze frame data using the hand-held tester or the OBD II scan tool, as freeze frame data records the engine conditions when a malfunction is detected.

For circuit wiring diagram, diagnosis and repair procedure (Scheme 699)& (Scheme 700).

Scheme 699

Scheme 699: Diagnosis & Repair

Scheme 700

Note. Using hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.

After confirming DTC P0100, P0102 or P0103, use the hand-held tester or the OBD II scan tool to confirm the mass air flow ratio from the DIAGNOSIS/ENHANCED OBD II/DATA LIST/ALL. If MAF meter air flow rate is 0.0 gm/sec., VG circuit may be open or shorted, or power source circuit may be open. If MAF meter air flow rate is 271.0 gm/sec. or more with engine idling and at normal operating temperature, E2G circuit may be open.

For circuit wiring diagram, diagnosis and repair procedure (Scheme 701), (Scheme 702) & (Scheme 703).

Scheme 701

Scheme 701: Diagnosis & Repair

Scheme 702

Scheme 703

Scheme 704

Mass Airflow (MAF) meter uses a platinum hot wire which is maintained at a constant temperature by controlling the current flow through the hot wire. Current flow is then measured as an output voltage. MAF meter may also be referred to as airflow meter.

Note. Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.

Check for any other DTCs. If other DTCs exist, diagnose and repair those DTCs first and retest. If only DTC P0101 exists, replace MAF meter. MAF meter is bolted to air intake hose, near air cleaner assembly and contains a Black 5-pin electrical connector. For removal and installation of components, see REMOVAL & INSTALLATION - V6 & V8 article.

Note. Using hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.

After confirming DTCs P0110, P0112 and/or P0113 use the hand-held tester or the OBD II scan tool to confirm the intake air temperature from the DIAGNOSIS/ENHANCED OBD II/DATA LIST/ALL. Read the intake air temperature for IAT sensor. If displayed intake air temperature is -40°F (-40°C), IAT sensor circuit may be open. If displayed intake air temperature is 284°F (140°C) or more, IAT sensor circuit may be shorted.

For circuit wiring diagram, diagnosis and repair procedure (Scheme 705)- (Scheme 707).

For ECM location see scheme 7 For connector views (Scheme 687)and (Scheme 704). For testing of systems or components, see SYSTEM & COMPONENT TESTING - V6 & V8 article. For removal and installation of components, see REMOVAL & INSTALLATION - V6 & V8 article.

Scheme 705

Scheme 705: Diagnosis & Repair

Scheme 706

Scheme 707

Note. Using hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.

After confirming DTCs P0115, P0117 and/or P0118, use the hand-held tester or the OBD II scan tool to confirm the engine coolant temperature from the DIAGNOSIS/ENHANCED OBD II/DATA LIST/ALL. Read the engine coolant temperature for ECT sensor. If displayed engine coolant temperature is -40°F (-40°C), ECT sensor circuit may be open. If displayed engine coolant temperature is 284°F (140°C) or more, ECT sensor circuit may be shorted.

For circuit wiring diagram, diagnosis and repair procedure (Scheme 708)- (Scheme 710).

Scheme 708

Scheme 708: Diagnosis & Repair

Scheme 709

Scheme 710

Note. Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.

Using Toyota hand-held tester or scan tool, check for any other DTCs. If only DTCs P0116 and/or P0125 exists, go to next step. If other DTCs exist, diagnose and repair those DTCs first and retest.
Remove and inspect cooling system thermostat for damage and proper operation. Thermostat is located behind thermostat housing on driver's side front of engine, just behind cooling fan. If thermostat is defective, replace thermostat. If thermostat is okay, replace ECT sensor. ECT sensor is located behind upper timing belt cover, on top of intake manifold and contains Dark Gray 2-pin electrical connector with Brown and Black/Blue wires. For removal and installation of components, see «REMOVAL & INSTALLATION - V6 & V8»(ref-151984) article.

Note. Using hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.

For diagnosis and repair procedure with Toyota hand-held tester or Enhanced OBD II scan tool (Scheme 711)- (Scheme 713).

For diagnosis and repair procedure with generic OBD II scan tool (Scheme 713)- (Scheme 714).

Scheme 711

Scheme 711: Diagnosis & Repair

Scheme 712

Scheme 713

Scheme 714

Throttle Position (TP) sensor uses 2 sensors which detect throttle opening and a malfunction of the TP sensor. TP sensor is located on throttle body and provides an input voltage of 0-5 volts to VTA and VTA2 terminals at Engine Control Module (ECM) in proportion to throttle opening. ECM uses input signals and controls the throttle control motor to provide proper throttle valve opening in response to driving conditions.

Note. Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.

Check for any other DTCs. If other DTCs exist, diagnose and repair those DTCs first and retest. If only DTC P0121 exists, replace TP sensor with throttle body as an assembly. For removal and installation of components, see REMOVAL & INSTALLATION - V6 & V8 article.

Note. Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame records engine conditions when malfunction is detected.

Remove and inspect cooling system thermostat for damage and proper operation. Thermostat is located behind thermostat housing on driver's side front of engine, just behind cooling fan. If thermostat is okay, go to next step. If thermostat is defective, replace thermostat.
Using Toyota hand-held tester or scan tool, check for any other DTCs. If other DTCs exist, diagnose and repair those DTCs first and retest. If only DTC P0128 exists, replace ECM. ECM is located behind glove box. see scheme 7

To aid in diagnosis or to confirm repair success, perform confirmation driving pattern. (Scheme 715)

Scheme 715

Scheme 715: Test Drive Confirmation

Note. Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.

For diagnosis and repair procedure (Scheme 717)- (Scheme 719). For circuit wiring diagram (Scheme 716) When prompted to perform confirmation driving pattern, see TEST DRIVE CONFIRMATION.

Scheme 716

Scheme 716: Diagnosis & Repair

Scheme 717

Scheme 718

Scheme 719

Note. Clear ECM of all DTCs before performing this procedure. See CLEARING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM.

Test drive confirmation may be performed to operate vehicle under conditions which may cause DTC to be set. When performing test drive confirmation, procedures must be performed exactly as listed or the malfunction may not be detected. If Toyota hand-held tester is available, go to next step. If Toyota hand-held tester is not available, go to step 4.
Connect hand-held tester to Data Link Connector No. 3 (DLC3) at driver's side of instrument panel. see scheme 1 Switch hand-held tester from NORMAL mode to CHECK mode.
Start engine and warm engine to normal operating temperature. Ensure all accessories are off. Drive vehicle at 38-75 MPH with engine speed of 1600-3200 RPM for 3-5 minutes. Check operation of Malfunction Indicator Light (MIL). If MIL illuminates, malfunction exists and DTC is set. If MIL does not illuminate, malfunction does not exist.
Start engine and warm engine to normal operating temperature. Ensure all accessories are off. Drive vehicle at 38-75 MPH with engine speed of 1600-3200 RPM for 3-5 minutes.
Turn ignition off. Repeat step 4 again and then check operation of Malfunction Indicator Light (MIL). If MIL illuminates, malfunction exists and DTC is set. If MIL does not illuminate, malfunction does not exist.

Note. Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.

For diagnosis and repair procedure (Scheme 720)- (Scheme 726).

For ECM location see scheme 7 For ECM connector view (Scheme 687) To identify circuits referenced in testing, see ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL. For vacuum or EVAP hose routing, see VACUUM DIAGRAMS article. For testing of systems or components, see BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article or SYSTEM & COMPONENT TESTING - V6 & V8 article. For adjustments, see ON-VEHICLE ADJUSTMENTS - V6 & V8 article. For removal and installation of components, see REMOVAL & INSTALLATION - V6 & V8 article.

Scheme 720

Scheme 720: Diagnosis & Repair

Scheme 721

Note. At this point in diagnosis, review the following list of hints while referring to (Scheme 722).

Note. In the following list, the voltage in parenthesis are as seen on OBD II scan tool. The voltages outside parenthesis are as seen on Toyota hand-held tester.

Whenever the output voltage of the A/F sensor remains at approximately 3.3 volts (0.66 volt) under any conditions as well as the above conditions, the A/F sensor may have an open circuit. (This will happen also when the A/F sensor heater has an open circuit). See drawing in (Scheme 722).
Whenever the output voltage of the A/F sensor remains at a certain value of approximately 3.8 volts (0.76 volt) or more, or 2.8 volts (0.56 volt) or less under any condition as well as the above conditions, the A/F sensor may have a short circuit. See drawing in (Scheme 722).
The ECM will stop fuel injection (fuel cut) during engine deceleration. This will cause a lean condition and should result in a momentary increase in A/F ratio sensor voltage.
The ECM must establish a closed throttle position learned value to perform fuel cut. If the battery terminal has been disconnected, the vehicle must be driven over 10 mph to allow the ECM to relearn the closed throttle position.
When the vehicle is driven, in the case that the output voltage of the A/F sensor is below 2.8 volts (0.56 volt) during fuel enrichment, (for example, when the vehicle tries to overtake another vehicle on a highway, the vehicle speed is suddenly increased with the accelerator pedal fully depressed), the A/F sensor is functioning normally.
The A/F sensor is a current output element, and therefore the current is converted into voltage inside the ECM. If measuring voltage at connectors of A/F ratio sensor or ECM, you will obtain a constant voltage. If voltage is not as specified, proceed to step 10). (Scheme 723)- (Scheme 725). If voltages are as specified, go to step 17). (Scheme 725)& (Scheme 726). When it is necessary to perform CONFIRMATION DRIVING PATTERN, see «TEST DRIVE CONFIRMATION»(ref-157557-S02637365022003081500000).

Scheme 722

Scheme 723

Scheme 724

Scheme 725

Scheme 726

Note. Read freeze frame data using the hand-held tester or the OBD II scan tool, as freeze frame data records the engine conditions when a malfunction is detected.

For diagnosis and repair procedure (Scheme 727)& (Scheme 728).

Scheme 727

Scheme 727: Diagnosis & Repair

Scheme 728

Note. Clear ECM of all DTCs before performing this procedure. See CLEARING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM.

When performing test drive confirmation, procedures must be performed exactly as listed or the malfunction may not be detected. Connect Toyota hand-held tester or scan tool to Data Link Connector No. 3 (DLC3) at driver's side of instrument panel. see scheme 1 Check for any DTCs and read FREEZE FRAME data. Record DTCs and freeze frame data. If using hand-held tester, switch hand-held tester to CHECK mode.
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 the data list on hand-held tester or scan tool.
Drive vehicle at specified engine speeds for specified amount of time. See «DRIVING PATTERN»(ref-157557-S04255967622003081500000). If using OBD II scan tool, turn ignition off after symptom is simulated the first time (1 trip detection logic), then repeat test drive again trying to get a misfire again and set DTC (2 trip detection logic). If using hand-held tester or scan tool, if a misfire is detected, a DTC will set and misfire will be indicated in freeze frame data. Be careful not to turn ignition off, as that switches the diagnostic system from check (test) mode to normal mode. All DTCs, freeze frame data, etc. would be erased. Check for misfire DTCs by monitoring DTC and freeze frame data. Record any data. Turn ignition off and wait a minimum of 5 seconds. DRIVING PATTERN Engine RPM Specified Time Idling 3 1/2 Minutes Or More 1000 3 Minutes Or More 2000 1 1/2 Minutes Or More 3000 1 Minute Or More

Note. When 2 or more DTCs for misfiring cylinder are recorded repeatedly and DTC P0300 does not exist, it indicates misfires were detected and recorded at different times. If misfire cannot be reproduced, the reason may be because vehicle was driven with a lack of fuel, improper fuel, fouled spark plug, etc. Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected. If COOLANT TEMP displayed in freeze frame data is less than 176°F (80°C), there is a possibility that misfire only exists during warm-up.

Note. If oscilloscope is available, fuel injector operation on misfiring cylinder may be checked by reading the fuel injector signal waveform pattern and fuel injector duration signal waveform pattern which may be checked by connecting oscilloscope between ECM 34-pin connector E4 terminal No. 7 (E01) (White/Black wire) and fuel injector driver terminals (#10 - #60) for misfiring cylinder at ECM with engine idling. ECM is located behind glove box. see scheme 7 For ECM electrical connector terminal identification (Scheme 687) For fuel injector driver identification, see IDENTIFYING ECM FUEL INJECTOR DRIVER TERMINALS. Fuel injector signal waveform pattern and fuel injector duration signal waveform pattern should be properly displayed within proper intervals. (Scheme 738)

For circuit wiring diagram, diagnosis and repair procedure (Scheme 729)- (Scheme 737).

When it is necessary to perform TEST DRIVE CONFIRMATION pattern, see TEST DRIVE CONFIRMATION .

When ignition coil(s) and/or ignition coil(s) and ignitor circuit diagnosis is necessary, go to DTC P0351-DTC P0356: IGNITION COIL "A"-"F" PRIMARY/SECONDARY CIRCUIT . If necessary to check or replace engine timing chain and/or timing gear(s), see appropriate article in ENGINES. For vacuum or EVAP hose routing, see VACUUM DIAGRAMS article. For testing of systems or components, see BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article or SYSTEM & COMPONENT TESTING - V6 & V8 article. For adjustments, see ON-VEHICLE ADJUSTMENTS - V6 & V8 article. For removal and installation of components, see REMOVAL & INSTALLATION - V6 & V8 article.

Scheme 729

Scheme 729: Diagnosis & Repair

Scheme 730

Scheme 731

Scheme 732

Scheme 733

Scheme 734

Scheme 735

Scheme 736

Scheme 737

Scheme 738

Fuel Injector No. (1)	ECM Electrical Connector & Terminal (2)	Wire Color
1	E4 Terminal No. 1 (#10)	Red/Black
2	E4 Terminal No. 2 (#20)	Black
3	E4 Terminal No. 3 (#30)	Red
4	E4 Terminal No. 4 (#40)	Green
5	E4 Terminal No. 5 (#50)	Yellow
6	E5 Terminal No. 3 (#60)	Blue
(1) Fuel injector No. 1 is front fuel injector on passenger's side of engine. Fuel injector No. 2 is front fuel injector on driver's side of engine. Fuel injectors No. 1, 3 and 5 are on passenger's side of engine. Fuel injectors No. 2, 4 and 6 are on driver's side of engine. (2) For ECM electrical connector terminal identification (Scheme 687)

(1)	Fuel injector No. 1 is front fuel injector on passenger's side of engine. Fuel injector No. 2 is front fuel injector on driver's side of engine. Fuel injectors No. 1, 3 and 5 are on passenger's side of engine. Fuel injectors No. 2, 4 and 6 are on driver's side of engine.

(2)	For ECM electrical connector terminal identification (Scheme 687)

IDENTIFYING ECM FUEL INJECTOR DRIVER TERMINALS

Note. Read freeze frame data using the hand-held tester or the OBD II scan tool, as freeze frame data records the engine conditions when a malfunction is detected.

Note. Normal mode vibration frequency of knock sensor is 6 kHz to 15 kHz. If oscilloscope is available, knock sensor No. 1 and No. 2 operation may be checked by reading knock sensor waveform patterns with engine at 4000 RPM. (Scheme 742)for proper probe placement and terminal selections.

For circuit wiring diagram, diagnosis and repair procedure (Scheme 739)- (Scheme 742). The 6-pin connector ED1 is located rear side of right bank cylinder head.

For ECM location see scheme 7 For ECM connector view (Scheme 687) Knock sensors are located on cylinder block, just below cylinder head and under intake manifold. (Scheme 743) For testing of systems or components, see SYSTEM & COMPONENT TESTING - V6 & V8 article. For removal and installation of components, see REMOVAL & INSTALLATION - V6 & V8 article.

Scheme 739

Scheme 739: Diagnosis & Repair

Scheme 740

Scheme 741

Scheme 742

Scheme 743

Perform troubleshooting DTC P0335 first. If no trouble is found, troubleshoot the engine mechanical systems. Read freeze frame data using the hand-held tester or the OBD II scan tool, as freeze frame data records the engine conditions when a malfunction is detected.

If an oscilloscope is available, crankshaft position sensor operation may be checked by reading crankshaft position sensor waveform pattern with engine idling. This may be done by monitoring the crankshaft position sensor signal which is referred to as the NE signal. Crankshaft position sensor waveform pattern may be checked by connecting oscilloscope between ECM 32-pin connector E6 terminals No. 25 (NE+) (Black wire) and No. 24 (NE-) (White wire). ECM is located behind glove box. see scheme 7 For ECM electrical connector terminal identification (Scheme 687) Crankshaft position sensor waveform pattern should be properly displayed. (Scheme 747)

For circuit wiring diagram, diagnosis and repair procedure (Scheme 744)& (Scheme 745). For ECM location see scheme 7 For ECM connector view (Scheme 687) For location of CKP sensor (Scheme 746) For testing of systems or components, see BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article or SYSTEM & COMPONENT TESTING - V6 & V8 article. For removal and installation of components, see REMOVAL & INSTALLATION - V6 & V8 article.

Scheme 744

Scheme 744: Diagnosis & Repair

Scheme 745

Scheme 746

Scheme 747

Note. Read freeze frame data using the hand-held tester or the OBD II scan tool, as freeze frame data records the engine conditions when a malfunction is detected.

If oscilloscope is available, VVT (CMP) sensor operation may be checked by reading VVT sensor waveform pattern with engine idling. This may be done by monitoring the VVT sensor signal which is referred to as the VV1+ (R/H) and VV2+ (L/H) signal. VVT sensor waveform pattern may be checked by connecting oscilloscope between ECM 32-pin connector E6 terminals No. 27 (VV1+) (R/H) (Red wire) and No. 24 (NE-) (White wire). For VVT2+ (L/H) waveform pattern may be checked between ECM 32-pin connector E6 terminals No. 26 (VV2+) (L/H) (Yellow wire) and No. 24 (NE-) (White wire). ECM is located behind glove box. see scheme 7 For ECM electrical connector terminal identification (Scheme 687) VVT sensor waveform patterns should be properly displayed. (Scheme 747)

For diagnosis and repair procedure (Scheme 748)& (Scheme 749).

For location of VVT (CMP) sensor (Scheme 752) If necessary to replace VVT (CMP) sensor(s) (Scheme 750) For location of VVT (CMP) sensor signal plate (Scheme 751) If necessary to replace VVT (CMP) sensor signal plate, see appropriate ENGINES article. For testing of systems or components, see BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article or SYSTEM & COMPONENT TESTING - V6 & V8 article. For removal and installation of components, see REMOVAL & INSTALLATION - V6 & V8 article.

Scheme 748

Scheme 748: Diagnosis & Repair

Scheme 749

Scheme 750

Scheme 751

Scheme 752

Read freeze frame data using the hand-held tester or the OBD II scan tool, as freeze frame data records the engine conditions when a malfunction is detected.

If oscilloscope is available, ignition coil and ignitor operation may be checked by reading IGT and IGF signal waveform pattern with engine cranking or idling. This may be done by monitoring the IGT and IGF signal waveform pattern. It may be checked by connecting oscilloscope between IGT1 - IGT6 circuit and E1, and the IGF and E1. ECM 32-pin connector E6 terminals No. 1 (-) (E1) is ECM sensor ground. IGT and IGF waveform patterns should be properly displayed. (Scheme 753)

For circuit wiring diagram, diagnosis and repair procedure (Scheme 754)- (Scheme 758).

For ECM location see scheme 7 For ECM connector view (Scheme 687) For testing of systems or components, see BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article or SYSTEM & COMPONENT TESTING - V6 & V8 article. For removal and installation of components, see REMOVAL & INSTALLATION - V6 & V8 article.

Scheme 753

Scheme 753: Diagnosis & Repair

Scheme 754

Scheme 755

Scheme 756

Scheme 757

Scheme 758

The ECM observes the waveform of the oxygen sensor located behind the catalyst to determine whether the catalyst performance has deteriorated. If the catalyst is functioning normally, the waveform of the oxygen sensor located behind the catalyst switches back and forth between rich and lean much more slowly. When the waveform of the oxygen sensor located behind the catalyst alternates frequently between rich and lean, it indicates that catalyst performance has deteriorated. (Scheme 759)

Note. Read freeze frame data using the hand-held tester or the OBD II scan tool, as freeze frame data records the engine conditions when a malfunction is detected.

To aid in diagnosing a deteriorated catalytic converter it is recommended to first perform CONFIRMATION ENGINE RACING PATTERN .

For diagnosis and repair procedure (Scheme 759)& (Scheme 760).

For testing of systems or components, see SYSTEM & COMPONENT TESTING - V6 & V8 article. For removal and installation of components, see REMOVAL & INSTALLATION - V6 & V8 article.

Scheme 759

Scheme 759: Diagnosis & Repair

Scheme 760

Circuit Description Toyota 4Runner IV