Engine Control System Self Diagnostics - 2UZ-FE: Diagnosis Toyota 4Runner IV

MALFUNCTION INDICATOR LIGHT INSPECTION

Note. Malfunction Indicator Light (MIL) may also be referred to as CHECK ENGINE light. Inspect MIL to ensure it is operational and will come on if a Diagnostic Trouble Code (DTC) is set.

1. Turn ignition on. Check that MIL comes on and remains on. MIL is displayed as an engine icon located just below the tachometer on instrument cluster. If MIL comes on and remains on, go to next step. If MIL does not come on, check bulb circuit on instrument cluster and Violet wire and electrical connectors between MIL and Engine Control Module (ECM). See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article. ECM is located behind glove box. see scheme 2
2. Start engine and ensure MIL goes off. If MIL goes off, no malfunction is detected at this time. If MIL remains on or blinks with engine running, a malfunction is detected. Proceed to «TESTING PROCEDURE»(ref-151976-S34905420152003010900000).

TESTING PROCEDURE

Note. Many aftermarket OBD II scan tools are limited in diagnostic capabilities, using the SAE Recommended Practice J1978, which defined the basic requirements of an OBD II scan tool. Most manufacturers service manuals describe repair procedures that require scan tool diagnostic capabilities beyond the ability of the aftermarket OBD II scan tools using only SAE Recommended Practice J1978. To perform these diagnostic test functions without having each manufacturers hand-held tester requires enhanced OBD II scan tools using the basic requirements and a standard set of diagnostic test modes, the SAE Recommended Practice J1979, which defines the test modes used by both the vehicle and the OBD II scan tool to access vehicle information and functions.

To perform test procedures outlined in most manufacturers service manuals, an OBD II scan tool compliant with SAE J1979 is required to contain the following test modes

1. MODE 1 - Display current diagnostic data parameters.
2. MODE 2 - Display freeze frame data captured by the vehicle along with DTC(s).
3. MODE 3 - Display emission-related powertrain DTC(s).
4. MODE 4 - RESET ECM/PCM: Clear DTC(s), freeze frame data, and any other diagnostic information from the on-board controller's memory.
5. MODE 5 - Displays results of Oxygen Sensor monitoring tests.
6. MODE 6 - Displays results of on-board monitoring tests for non-continuously monitored systems.
7. MODE 7 - Displays results of on-board monitoring tests for continuously monitored systems and status of vehicles on-board readiness code tests. In addition to these standard set of diagnostic test modes, the SAE Recommended Practice J1979, some scan tool manufacturers have provided even more enhancements, such as road test support through capture of sequences of data parameters (SNAP SHOT MODE), and user-selectable parameter list (DATA LIST) allowing user to trade off update (refresh) rate for amount of data.
8. MODE 8 - Request control of on-board system, test or component.
9. MODE 9 - Displays vehicle information; VIN and calibration numbers, etc.

To ensure correct diagnosis and repair, testing should be done in the following sequence

1. Record Customer Complaint Ensure all customer complaints or observations are recorded. Test drive vehicle with customer when necessary for malfunction verification.
2. Retrieve Diagnostic Trouble Codes Using Toyota hand-held tester or scan tool, retrieve Diagnostic Trouble Codes (DTC) from Engine Control Module (ECM) and record any freeze frame data (if applicable). See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-151976-S20898033472003010900000) .
3. Clear Diagnostic Trouble Codes Using Toyota hand-held tester or scan tool, clear DTCs and freeze frame data from ECM. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-151976-S07849978262003010900000) .
4. Visual Inspection Inspect all electrical connectors and wiring for suspected circuit or component. Ensure all connections are clean and tight.
5. Confirm Symptoms & Diagnostic Trouble Codes Perform road test. Determine if original symptoms still exist. Using scan tool or Toyota hand-held tester, retrieve DTCs from ECM. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-151976-S20898033472003010900000) .
6. Diagnose & Repair Diagnostic Trouble Codes Perform appropriate DTC test listed under DIAGNOSTIC TESTS as necessary. For DTC descriptions, see «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-151976-S41169390082003010900000) . If no DTCs are present and a no start condition exists, proceed to «BASIC DIAGNOSTIC PROCEDURES - V6 & V8»(ref-151953) article. If no DTCs are present and a driveability condition exists, proceed to «TROUBLESHOOTING - NO CODES»(ref-151977) article for diagnosis by symptom (i.e., ROUGH IDLE, ENGINE STALLS, etc.).
7. Verification Procedure After repairs have been completed, clear all DTCs from ECM. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-151976-S07849978262003010900000) . Perform road test. Ensure no DTCs exist and all symptoms and/or complaints have been repaired.

RETRIEVING DIAGNOSTIC TROUBLE CODES

Note. Diagnostic Trouble Codes (DTC) may be retrieved using Toyota hand-held tester or On-Board Diagnostic (OBD-II) scan tool that complies with SAE standard J-1978. Toyota hand-held tester or OBD-II scan tool may be operated in NORMAL mode when retrieving DTCs. Using Toyota hand-held tester or On-Board Diagnostic (OBD-II) scan tool that complies with SAE standard J-1979 may be used to check first trip DTC using MODE 7, the CONTINUOUS TEST RESULTS monitor function on scan tool.

NORMAL mode is used to retrieve DTCs from Engine Control Module (ECM). CHECK mode is used to check for DTCs when operating vehicle to simulate conditions during which DTC was set. CHECK mode contains a higher sensitivity to detect malfunctions. CHECK mode helps determine malfunctions caused by poor electrical connections or intermittent problems which are difficult to determine using NORMAL mode.

Note. If using Toyota hand-held tester, when ignition switch is turned from ON to ACC or OFF position during CHECK mode, hand-held tester is switched from NORMAL mode to CHECK mode or from CHECK mode to NORMAL mode, all DTCs and freeze frame data will be erased from ECM. DO NOT switch modes until all DTCs and freeze frame data have been recorded.

NORMAL Mode Diagnostic Trouble Code Retrieval

1. Connect Toyota hand-held tester or scan tool to Data Link Connector (DLC3) at driver's side of instrument panel. see scheme 1 Turn ignition on with engine off. Turn hand-held tester or scan tool on. Using hand-held tester or scan tool manufacturer's instructions, check for DTCs and freeze frame data.
2. If hand-held tester or scan tool does not display UNABLE TO CONNECT TO VEHICLE, go to next step. If hand-held tester or scan tool displays UNABLE TO CONNECT TO VEHICLE, check DLC3. See «DATA LINK CONNECTOR NO. 3 INSPECTION»(ref-151976-S33636861932003010900000) under SCAN TOOL PROBLEMS.
3. Record any DTCs and freeze frame data displayed for system diagnosis. If driveability problem exists and no DTCs are present, go to «TROUBLESHOOTING - NO CODES»(ref-151977) article for diagnosis by symptom.
4. If any DTCs exist, perform appropriate DTC test under «DIAGNOSTIC TESTS»(ref-151976-S21028076422003010900000). For DTC descriptions, see «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-151976-S41169390082003010900000). For information on freeze frame data, see «FREEZE FRAME DATA»(ref-151976-S17863610262003010900000). For information on two-trip detection logic codes, see «TWO-TRIP DETECTION LOGIC»(ref-151976-S10576698782003010900000).
5. After repairs for DTC have been completed, DTC must be cleared from Engine Control Module (ECM). See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-151976-S07849978262003010900000). Road test vehicle to ensure all symptoms and/or complaints have been repaired.

CHECK Mode Diagnostic Trouble Code Retrieval (Described Using Toyota Hand-Held Tester Only)

Note. If using Toyota hand-held tester, if ignition switch is turned from ON to ACC or OFF position during CHECK mode, all DTCs and freeze frame data will be erased from Engine Control Module (ECM). DO NOT switch from CHECK MODE to NORMAL mode until all DTCs and freeze frame data are recorded.

1. Ensure vehicle battery is fully charged. Apply parking brake. Place transmission in Park or Neutral. Ensure A/C and ignition are off. Check that throttle valve is fully closed. Connect hand-held tester to Data Link Connector (DLC3) at driver's side of instrument panel. see scheme 1 Turn ignition on and then turn hand-held tester on.
2. Switch hand-held tester from NORMAL mode to CHECK mode. Ensure Malfunction Indicator Light (MIL) on instrument cluster flashes to indicate CHECK mode operation. Start engine. If no DTCs are present, MIL will turn off. Try to simulate conditions of driveability complaint described by customer.
3. Record any DTCs and freeze frame data displayed for system diagnosis. If driveability problem exists and no DTCs are present, go to «TROUBLESHOOTING - NO CODES»(ref-151977) article for diagnosis by symptom.
4. If any DTCs exist, perform appropriate DTC test under «DIAGNOSTIC TESTS»(ref-151976-S21028076422003010900000). For DTC descriptions, see «DIAGNOSTIC TROUBLE CODE DEFINITIONS»(ref-151976-S41169390082003010900000). For information on freeze frame data, see «FREEZE FRAME DATA»(ref-151976-S17863610262003010900000). For information on two-trip detection logic DTCs, see «TWO-TRIP DETECTION LOGIC»(ref-151976-S10576698782003010900000).
5. After repairs for DTC have been completed, DTC must be cleared from Engine Control Module (ECM). See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-151976-S07849978262003010900000). Road test vehicle to ensure all symptoms and/or complaints have been repaired.

CLEARING DIAGNOSTIC TROUBLE CODES

1. After repairs for Diagnostic Trouble Codes (DTC) have been completed, DTCs and freeze frame data should be cleared from Engine Control Module (ECM) memory. Using scan tool or Toyota hand-held tester, follow the manufacturer's instructions and clear DTCs and freeze frame data from ECM.
2. DTCs and freeze frame data may also be cleared by removing EFI fuse (20-amp). EFI fuse is located in fuse/relay box at driver's side front corner of engine compartment. DTCs and freeze frame data may also be cleared by disconnecting negative battery cable. However, other various memory functions such as the clock, radio, alarm, seats, etc. will be cleared and must be reset.

TEST DRIVE CONFIRMATION

1. On certain Diagnostic Trouble Codes (DTC), once DTC has been cleared from Engine Control Module (ECM) memory, test drive confirmation can be performed to verify repairs are made and that DTC does not reset. Test drive confirmation will duplicate conditions required to set specified DTCs.
2. Test drive confirmation lists the procedure to be performed to check that DTC does not reset. Test drive confirmation applies only to specific DTCs. Test drive confirmation will be included within proper DTC test under DIAGNOSTIC TESTS.

DIAGNOSTIC TROUBLE CODE DEFINITIONS

DIAGNOSTIC TROUBLE CODE DEFINITIONS

DIAGNOSTIC TESTS

Note. Before performing any diagnostic test, refer to SELF-DIAGNOSTIC SYSTEM for diagnostic system functions and system diagnostic procedures. Also check for any related Technical Service Bulletins (TSBs).

Note. When performing diagnostic tests, it may be necessary to identify Engine Control Module (ECM) electrical connector terminals which are referenced to in testing procedure. (Scheme 58)

Scheme 58

Diagnosis & Repair

1. Turn ignition off. Disconnect HO2S 4-pin connector. (Scheme 59) Measure resistance between HO2S 4-pin connector terminals No. 2 (+B) and No. 1 (HT). Make note of measurement. Then, measure resistance between HO2S 4-pin connector terminals No. 1 (HT) and No. 4 (E1). See «HO2S HEATER RESISTANCE SPECIFICATIONS»(ref-151976-S13340720022003080800000). If resistance is within specification, go to next step. If resistance is not within specification, replace HO2S. See «HEATED OXYGEN SENSOR»(ref-151984-S41146403752003010900000) under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article. HO2S HEATER RESISTANCE SPECIFICATIONS Terminals No. Resistance in Ohms @ 68°F (20°C) 1 (HT) & 2 (B+) 11-16 1 (HT) & 4 (E1) No Continuity
2. Remove EFI relay from engine room relay box. Test relay. See EFI RELAY under «MODULES, MOTORS, RELAYS & SOLENOIDS»(ref-151979-S10779012602003010900000) in SYSTEM & COMPONENT TESTING - V6 & V8 article. If relay is bad, replace it. If relay is Ok, reinstall relay and go to next step.
3. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2 Turn ignition on. Backprobing, measure voltage between ECM 32-pin connector E6 terminal No. 1 (-) (Brown wire) and ECM 35-pin connector E5 terminals No. 4 (+) (Light/Green wire), No. 5 (+) (Green/Yellow wire), No. 33 (+) (Black/Blue wire) and No. 25 (+) ( Pink wire). (Scheme 58) Voltage should be 9-14 volts. If voltage is not within specification, go to next step. If voltage is within specification, replace ECM. NOTE: ECM 35-pin connector E5 terminal No. 4 (HT1A) is for HO2S (Bank 1 Sensor 1). ECM 35-pin connector E5 terminal No. 5 (HT1B) is for HO2S (Bank 1 Sensor 2). ECM 35-pin connector E5 terminal No. 33 (HT2A) is for HO2S (Bank 2 Sensor 1). ECM 35-pin connector E5 terminal No. 25 (HT2B) is for HO2S (Bank 2 Sensor 2).
4. Turn ignition off. Disconnect ECM 35-pin connector E5 and suspect HO2S 4-pin connector(s). Check continuity between appropriate ECM 35-pin connector terminal and appropriate HO2S connector terminal No. 1. There should be continuity. Then, check continuity between ground and appropriate HO2S connector terminal No. 1. There should be no continuity. If continuity is as specified, go to next step. If continuity is not as specified, repair wiring as necessary. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article. Then go to next step.
5. Check EFI fuse No. 2 located in engine room fuse/relay box. Replace as necessary. Disconnect EFI relay from engine room fuse/relay box. Check continuity between EFI main relay socket terminal No. 3 and suspect HO2S 4-pin connector terminal No. 2 (B+). Continuity should exist. Then, check continuity between ground and EFI main relay socket terminal No. 3. Continuity should not exist. If continuity is as specified, replace ECM. If continuity is not as specified, repair open or short circuit in wire or connector as necessary. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article.

Scheme 59

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 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. See AIRFLOW METER under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.

1. Connect Toyota hand-held tester or scan tool to Data Link Connector (DLC3) at driver's side of instrument panel. see scheme 1 Turn ignition on and then turn hand-held tester or scan tool on.
2. Using hand-held tester or scan tool, read engine coolant temperature for ECT sensor. If displayed engine coolant temperature is -40°F (-40°C), go to next step. If displayed engine coolant temperature is 284°F (140°C) or more, go to step 8. If displayed engine coolant temperature is same as actual engine coolant temperature, problem is intermittent. Check for defective connections or intermittent problem in wiring between ECT sensor and ECM. ECT sensor is located behind upper timing belt cover, on top of intake manifold and contains Black 2-pin electrical connector with Brown and Red/Blue wires. ECM is located behind glove box. see scheme 2
3. Turn ignition off. Disconnect ECT sensor 2-pin connector. ECT sensor is located behind upper timing belt cover, on top of intake manifold and contains Black 2-pin electrical connector with Brown and Red/Blue wires. Connect jumper wire between both terminals on electrical connector for ECT sensor.
4. Turn ignition on. Using hand-held tester or scan tool, read engine coolant temperature for ECT sensor. If displayed engine coolant temperature is less than 284°F (140°C), go to next step. If displayed engine coolant temperature is 284°F (140°C) or more, check for defective electrical connections at ECT sensor and electrical connector. If electrical connections are defective, repair as necessary. If electrical connections are okay, replace ECT sensor.
5. Turn ignition off. Remove jumper wire. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2 Ensure electrical connectors at ECM are securely installed so all terminals in electrical connectors are contacting terminals in ECM.
6. Ensure electrical connector at ECT sensor is still disconnected. Connect jumper wire between ECM 34-pin connector E4 terminals No. 19 (Red/Blue wire) and No. 28 (Brown wire). (Scheme 58) This is the E2 and THW terminals on ECM.
7. Turn ignition on. Using hand-held tester or scan tool, read engine coolant temperature for ECT sensor. If displayed engine coolant temperature is 284°F (140°C) or more, repair open Brown wire or Red/Blue wire or connectors between ECT sensor and ECM. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article. If displayed engine coolant temperature is not 284°F (140°C) or more, replace ECM.
8. Turn ignition off. Disconnect electrical connector at ECT sensor. ECT sensor is located behind upper timing belt cover, on top of intake manifold and contains Black 2-pin electrical connector with Brown and Red/Blue wires.
9. Turn ignition on. Using hand-held tester or scan tool, read engine coolant temperature for ECT sensor. If displayed engine coolant temperature is not -40°F (-40°C), go to next step. If displayed engine coolant temperature is -40°F (-40°C), replace ECT sensor.
10. Turn ignition off. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2 Disconnect ECM 34-pin connector E4. (Scheme 58) Ensure electrical connector is still disconnected at ECT sensor.
11. Turn ignition on. Using hand-held tester or scan tool, read engine coolant temperature for ECT sensor. If displayed engine coolant temperature is -40°F (-40°C), repair short in wiring harness and electrical connectors between ECT sensor and ECM. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article. If displayed engine coolant temperature is not -40°F (-40°C), replace ECM.

1. 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.
2. 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 Black 2-pin electrical connector with Brown and Red/Blue wires.

1. If Toyota hand-held tester is available, go to next step. If Toyota hand-held tester is not available, go to step 4.
2. Connect hand-held tester to Data Link Connector (DLC3) at driver's side of instrument panel. see scheme 1 Turn ignition on and then turn hand-held tester on.
3. Using hand-held tester or OBD II (enhanced) scan tool, monitor throttle valve opening in the DATA LIST for VTA1 and VTA2 circuits with accelerator pedal released and with accelerator pedal depressed. VTA1 circuit is displayed as a percentage and VTA2 circuit is displayed as a voltage. With accelerator pedal released, VTA1 circuit should be 10-24 percent and VTA2 circuit should be 2.1-3.1 volts. With accelerator pedal depressed, VTA circuit should be 64-96 percent and VTA2 circuit should be 4.5-5.5 volts. If throttle valve opening readings are not within specification, go to next step. If throttle valve opening readings are within specification, replace ECM. ECM is located behind glove box. see scheme 2
4. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2
5. Turn ignition off. Disconnect TP sensor 6-pin connector and ECM 34-pin connector E4. (Scheme 60) Check continuity between TP sensor and ECM connectors terminals. See «CONTINUITY CHECK BETWEEN TP SENSOR & ECM CONNECTORS»(ref-151976-S08073023452003081100000) for terminal selections. If continuity is as specified, go to next step. If continuity is not as specified, repair or replace harness and connectors as necessary. CONTINUITY CHECK BETWEEN TP SENSOR & ECM CONNECTORS TP Sensor & ECM Terminals No. (Wire Color) Specified Condition Of Wire No. 5 & No. 18 (Blue/Red) Continuity No. 6 & No. 21 (Yellow) Continuity No. 4 & No. 31 (Red/Black) Continuity No. 3 & No. 28 (Brown) Continuity No. 5 & Body Ground (Blue/Red) No Continuity No. 6 & Body Ground (Yellow) No Continuity No. 4 & Body Ground (Red/Black) No Continuity
6. Reconnect ECM 34-pin connector E4. Turn ignition on. Measure voltage between ECM terminals No. 18 (Blue/Red wire) and No. 28 (Brown wire). (Scheme 58) This is the E2 and VC terminals on ECM. Voltage should be 4.5-5.5 volts. If voltage is within specification, replace throttle body with motor assembly, then, go to next step. See «THROTTLE BODY»(ref-151984-S20444146202003010900000) under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article. If voltage is not within specification, replace ECM.
7. Using hand-held tester or OBD II scan tool, clear DTC(s). See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-151976-S07849978262003010900000). Start engine and allow engine to idle for 15 seconds or more. Check for DTCs. If DTCs are set, replace ECM. If no DTCs are set, troubleshooting is complete.

Scheme 60

Circuit Description

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 VTA1 and VTA2 terminals at 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. DTC is set when improper input signals from TP sensor are received at ECM. If DTC(s) exist, throttle valve is locked at a certain opening angle. Also when this occurs, the whole electronically controlled throttle operation is cancelled until the system returns to normal and ignition switch is turned off. Possible cause is defective TP sensor.

Diagnostic Aids

This DTC uses two-trip detection logic. 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 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. See THROTTLE BODY under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.

1. 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.
2. 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 2

1. 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.
2. Connect hand-held tester to Data Link Connector (DLC3) at driver's side of instrument panel. see scheme 1 Switch hand-held tester from NORMAL mode to CHECK mode.
3. 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.
4. 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.
5. 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.

1. Using Toyota hand-held tester or scan tool, check for any other DTCs. If only DTCs P0130, P0150, P2195, P2196, P2197 &/OR P2198 exists, go to next step. If other DTCs exist, diagnose and repair those DTCs first and retest.
2. With Toyota hand-held tester or scan tool still connected to DLC3, start engine and maintain engine speed at 2500 RPM for about 90 seconds to fully warm the oxygen sensor. Allow engine to idle.
3. Using hand-held tester or scan tool, monitor oxygen sensor output voltage with engine idling. HO2S output should alternate between less than 0.4 volt and more than 0.55 volt. If voltage is as specified, go to step 11. If voltage is not as specified, go to next step.
4. Turn ignition off. Disconnect HO2S 4-pin connector. (Scheme 59) Measure resistance between HO2S 4-pin connector terminals No. 2 (+B) and No. 1 (HT). Make note of measurement. Then, measure resistance between HO2S 4-pin connector terminals No. 1 (HT) and No. 4 (E1). See «HO2S HEATER RESISTANCE SPECIFICATIONS»(ref-151976-S24001383152003081100000). If resistance is within specification, go to next step. If resistance is not within specification, replace HO2S. See «HEATED OXYGEN SENSOR»(ref-151984-S41146403752003010900000) under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article. HO2S HEATER RESISTANCE SPECIFICATIONS Terminals No. Resistance in Ohms @ 68F (20C) 1 (HT) & 2 (B+) 11-16 1 (HT) & 4 (E1) No Continuity
5. Remove EFI relay from engine room relay box. (Scheme 59) Test relay. See EFI RELAY under «MODULES, MOTORS, RELAYS & SOLENOIDS»(ref-151979-S10779012602003010900000) in SYSTEM & COMPONENT TESTING article. If relay is bad, replace it. If relay is Ok, reinstall relay and go to next step.
6. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2 Check continuity between ECM and HO2S connectors at terminals listed below. (Scheme 58)and (Scheme 59). ECM 35-pin connector E5 terminal No. 4 (HT1A) and HO2S (Bank 1 Sensor 1) terminal No. 1. Continuity should exist. ECM 35-pin connector E5 terminal No. 23 (OX1A) and HO2S (Bank 1 Sensor 1) terminal No. 3. Continuity should exist. ECM 35-pin connector E5 terminal No. 33 (HT2A) and HO2S (Bank 2 Sensor 1) terminal No. 1. Continuity should exist. ECM 35-pin connector E5 terminal No. 22 (OX2A) and HO2S (Bank 2 Sensor 1) terminal No. 3. Continuity should exist. ECM 35-pin connector E5 terminal No. 4 (HT1A) and body ground. Continuity should not exist. ECM 35-pin connector E5 terminal No. 23 (OX1A) and body ground. Continuity should not exist. ECM 35-pin connector E5 terminal No. 33 (HT2A) and body ground. Continuity should not exist. ECM 35-pin connector E5 terminal No. 22 (OX2A) and body ground. Continuity should not exist.
7. If continuity is as specified, go to next step. If continuity is not as specified, repair wiring as necessary. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article. Then go to next step.
8. Ensure engine oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem does not exist, go to next step. If problem exists, repair as necessary.
9. Check fuel pressure. See «FUEL PRESSURE»(ref-151953-S33614114892003010900000) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, repair fuel system as necessary.
10. Check operation of fuel injectors. See «FUEL CONTROL»(ref-151979-S22215092702003010900000) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. Fuel injector volume should be.20-.25 oz. (60-73 cc) within 15 seconds and difference in volume between each fuel injector should be less than.04 oz. (13 cc). Fuel injectors should not leak more than one drop every 12 minutes. If fuel injectors are okay, replace oxygen sensor. See «HEATED OXYGEN SENSOR»(ref-151984-S41146403752003010900000) under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article. If fuel injectors are defective, replace fuel injectors as necessary.
11. Using Toyota hand-held tester or scan tool, clear DTCs from ECM. Perform test drive confirmation and then go to next step. See «TEST DRIVE CONFIRMATION»(ref-151976-S28331386662003010900000).
12. Recheck for DTCs. If DTCs P0130, P0150, P2195, P2196, P2197 &/OR P2198 does not exist, go to next step. If DTCs P0130, P0150, P2195, P2196, P2197 &/OR P2198 exists, replace HO2S. See «HEATED OXYGEN SENSOR»(ref-151984-S41146403752003010900000) under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.
13. Verify if vehicle ran out of fuel. If vehicle ran out of fuel, DTCs P0130, P0150, P2195, P2196, P2197 &/OR P2198 was caused by the vehicle running out of fuel. If vehicle did not run out of fuel, problem is intermittent. Check for defective connections or intermittent problem in wiring. ECM is located behind glove box. see scheme 2

1. 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.
2. Connect hand-held tester to Data Link Connector (DLC3) at driver's side of instrument panel. see scheme 1 Switch hand-held tester from NORMAL mode to CHECK mode.
3. 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.
4. 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.
5. 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.

1. Using Toyota hand-held tester or scan tool, check for any other DTCs. If only DTCs P0133 and/or P0153 exists, go to next step. If other DTCs exist, diagnose and repair those DTCs first and retest.
2. With Toyota hand-held tester or scan tool still connected to DLC3, start engine and maintain engine speed at 2500 RPM for about 90 seconds to fully warm the oxygen sensor. Allow engine to idle.
3. Using hand-held tester or scan tool, monitor HO2S output voltage with engine idling. HO2S output alternates between less than 0.4 volt and more than 0.55 volt. If voltage is as specified, go to step 11. If voltage is not as specified, go to next step.
4. Turn ignition off. Disconnect HO2S 4-pin connector. (Scheme 59) Measure resistance between HO2S 4-pin connector terminals No. 2 (+B) and No. 1 (HT). Make note of measurement. Then, measure resistance between HO2S 4-pin connector terminals No. 1 (HT) and No. 4 (E1). See «HO2S HEATER RESISTANCE SPECIFICATIONS»(ref-151976-S24001383152003081100000). If resistance is within specification, go to next step. If resistance is not within specification, replace HO2S. See «HEATED OXYGEN SENSOR»(ref-151984-S41146403752003010900000) under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.
5. Remove EFI relay from engine room relay box. (Scheme 59) Test relay. See EFI RELAY under «MODULES, MOTORS, RELAYS & SOLENOIDS»(ref-151979-S10779012602003010900000) in SYSTEM & COMPONENT TESTING article. If relay is bad, replace it. If relay is Ok, reinstall relay and go to next step.
6. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2 Check continuity between ECM and HO2S connectors at terminals listed below. (Scheme 58)and (Scheme 59). ECM 35-pin connector E5 terminal No. 4 (HT1A) and HO2S (Bank 1 Sensor 1) terminal No. 1. Continuity should exist. ECM 35-pin connector E5 terminal No. 23 (OX1A) and HO2S (Bank 1 Sensor 1) terminal No. 3. Continuity should exist. ECM 35-pin connector E5 terminal No. 33 (HT2A) and HO2S (Bank 2 Sensor 1) terminal No. 1. Continuity should exist. ECM 35-pin connector E5 terminal No. 22 (OX2A) and HO2S (Bank 2 Sensor 1) terminal No. 3. Continuity should exist. ECM 35-pin connector E5 terminal No. 4 (HT1A) and body ground. Continuity should not exist. ECM 35-pin connector E5 terminal No. 23 (OX1A) and body ground. Continuity should not exist. ECM 35-pin connector E5 terminal No. 33 (HT2A) and body ground. Continuity should not exist. ECM 35-pin connector E5 terminal No. 22 (OX2A) and body ground. Continuity should not exist.
7. If continuity is as specified, go to next step. If continuity is not as specified, repair wiring as necessary. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article. Then go to next step.
8. Ensure engine oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem does not exist, go to next step. If problem exists, repair as necessary.
9. Check fuel pressure. See «FUEL PRESSURE»(ref-151953-S33614114892003010900000) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, repair fuel system as necessary.
10. Check operation of fuel injectors. See «FUEL CONTROL»(ref-151979-S22215092702003010900000) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. Fuel injector volume should be.20-.25 oz. (60-73 cc) within 15 seconds and difference in volume between each fuel injector should be less than.04 oz. (13 cc). Fuel injectors should not leak more than one drop every 12 minutes. If fuel injectors are okay, replace HO2S. See «HEATED OXYGEN SENSOR»(ref-151984-S41146403752003010900000) under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article. If fuel injectors are defective, replace fuel injectors as necessary.
11. Using Toyota hand-held tester or scan tool, clear DTCs from ECM. Perform test drive confirmation and then go to next step. See «TEST DRIVE CONFIRMATION»(ref-151976-S15170287452003010900000).
12. Recheck for DTCs. If DTCs P0133 and/or P0153 does not exist, go to next step. If DTCs P0133 and/or P0153 exists, replace HO2S. See «HEATED OXYGEN SENSOR»(ref-151984-S41146403752003010900000) under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.
13. Verify if vehicle ran out of fuel. If vehicle ran out of fuel, DTCs P0133 and/or P0153 was caused by the vehicle running out of fuel. If vehicle did not run out of fuel, problem is intermittent. Check for defective connections or intermittent problem in wiring. ECM is located behind glove box. see scheme 2

1. 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.
2. Connect hand-held tester to Data Link Connector (DLC3) at driver's side of instrument panel. see scheme 1 Switch hand-held tester from NORMAL mode to CHECK mode.
3. 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.
4. 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.
5. 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.

1. Using Toyota hand-held tester or scan tool, check for any other DTCs. If only DTCs P0134 and/or P0154 exists, go to next step. If other DTCs exist, diagnose and repair those DTCs first and retest.
2. With Toyota hand-held tester or scan tool still connected to DLC3, start engine and maintain engine speed at 2500 RPM for about 90 seconds to fully warm the oxygen sensor. Allow engine to idle.
3. Using hand-held tester or scan tool, monitor oxygen sensor output voltage with engine suddenly raced. Quickly rev engine to 4000 RPM 3 times. HO2S output should go RICH (0.4 volt and more) at least once. If voltage is as specified, go to step 14. If voltage is not as specified, go to next step.
4. Check for vacuum leak at PCV hose. Check condition of PCV hose. Repair or replace as necessary. Then, go to next step.
5. Turn ignition off. Disconnect HO2S 4-pin connector. (Scheme 59) Measure resistance between HO2S 4-pin connector terminals No. 2 (+B) and No. 1 (HT). Make note of measurement. Then, measure resistance between HO2S 4-pin connector terminals No. 1 (HT) and No. 4 (E1). See «HO2S HEATER RESISTANCE SPECIFICATIONS»(ref-151976-S24001383152003081100000). If resistance is within specification, go to next step. If resistance is not within specification, replace HO2S. See «HEATED OXYGEN SENSOR»(ref-151984-S41146403752003010900000) under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.
6. Remove EFI relay from engine room relay box. (Scheme 59) Test relay. See EFI RELAY under «MODULES, MOTORS, RELAYS & SOLENOIDS»(ref-151979-S10779012602003010900000) in SYSTEM & COMPONENT TESTING article. If relay is bad, replace it. If relay is Ok, reinstall relay and go to next step.
7. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2 Check continuity between ECM and HO2S connectors at terminals listed below. (Scheme 58)and (Scheme 59). ECM 35-pin connector E5 terminal No. 4 (HT1A) and HO2S (Bank 1 Sensor 1) terminal No. 1. Continuity should exist. ECM 35-pin connector E5 terminal No. 23 (OX1A) and HO2S (Bank 1 Sensor 1) terminal No. 3. Continuity should exist. ECM 35-pin connector E5 terminal No. 33 (HT2A) and HO2S (Bank 2 Sensor 1) terminal No. 1. Continuity should exist. ECM 35-pin connector E5 terminal No. 22 (OX2A) and HO2S (Bank 2 Sensor 1) terminal No. 3. Continuity should exist. ECM 35-pin connector E5 terminal No. 4 (HT1A) and body ground. Continuity should not exist. ECM 35-pin connector E5 terminal No. 23 (OX1A) and body ground. Continuity should not exist. ECM 35-pin connector E5 terminal No. 33 (HT2A) and body ground. Continuity should not exist. ECM 35-pin connector E5 terminal No. 22 (OX2A) and body ground. Continuity should not exist.
8. If continuity is as specified, go to next step. If continuity is not as specified, repair wiring as necessary. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article. Then go to next step.
9. Using hand-held tester or scan tool, monitor for misfires and related DTCs in the DATA LIST.
10. Ensure engine oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem does not exist, go to next step. If problem exists, repair as necessary.
11. Check fuel pressure. See «FUEL PRESSURE»(ref-151953-S33614114892003010900000) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, repair fuel system as necessary.
12. Check operation of fuel injectors. See «FUEL CONTROL»(ref-151979-S22215092702003010900000) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. Fuel injector volume should be.20-.25 oz. (60-73 cc) within 15 seconds and difference in volume between each fuel injector should be less than.04 oz. (13 cc). Fuel injectors should not leak more than one drop every 12 minutes. If fuel injectors are okay, replace oxygen sensor. See «HEATED OXYGEN SENSOR»(ref-151984-S41146403752003010900000) under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article. If fuel injectors are defective, replace fuel injectors as necessary.
13. Inspect the exhaust system for leaks especially near HO2S (Bank 1 & 2, Sensor 1). Repair or replace cause of exhaust system leak as necessary. Then go to next step.
14. Using Toyota hand-held tester or scan tool, clear DTCs from ECM. Perform test drive confirmation and then go to next step. See «TEST DRIVE CONFIRMATION»(ref-151976-S06320574722003081100000).
15. Recheck for DTCs. If DTCs P0134 and/or P0154 does not exist, go to next step. If DTCs P0134 and/or P0154 exists, replace ECM. ECM is located behind glove box. see scheme 2
16. Verify if vehicle ran out of fuel. If vehicle ran out of fuel, DTCs P0134 and/or P0154 was caused by the vehicle running out of fuel. If vehicle did not run out of fuel, problem is intermittent. Check for defective connections or intermittent problem in wiring. ECM is located behind glove box. see scheme 2

Scheme 61

Heated Oxygen Sensor (HO2S) monitors exhaust gas oxygen content and delivers input signals to Engine Control Module (ECM). HO2S is located on exhaust pipe, behind catalytic converter. HO2S may also be referred to as oxygen sensor (bank No. 1 & 2, sensor No. 2). ECM uses input signals to determine fuel injection system operation. DTC is set when HO2S output voltage remains at 0.40 volt or more, or 0.50 volt or less when vehicle is driven at 31 MPH with engine at normal operating temperature. Possible causes are

1. HO2S circuit is open or shorted (bank 1 & 2, sensor 2).
2. Defective HO2S (bank 1 & 2, sensor 2).
3. Defective HO2S heater (bank 1 & 2, sensor 2).
4. EFI relay defective.

This DTC uses two-trip detection logic. Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.

If DTCs related to MAF, IAT, TPS, HO2S, ECT and/or VPS are output simultaneously, the E2 sensor ground circuit at ECM 34-pin connector E4 terminal No. 2 (Brown wire) may be open. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article. For ECM electrical connector terminal identification (Scheme 58) It may be necessary to check intermediate connectors and ground point in circuit as well. Splice No. 18 is located behind passenger's side of instrument panel, above ECM. Intermediate connector "IE1" is located behind left kick panel. Ground connection "EF" is located on right side of left cylinder head.

1. 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.
2. Connect hand-held tester to Data Link Connector (DLC3) at driver's side of instrument panel. see scheme 1 Switch hand-held tester from NORMAL mode to CHECK mode.
3. 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.
4. 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.
5. 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.

1. Using Toyota hand-held tester or scan tool, check for any other DTCs. If only DTCs P0136 and/or P0156 exists, go to next step. If other DTCs exist, diagnose and repair those DTCs first and retest.
2. Check for open and short in wiring harness and electrical connectors between HO2S and ECM. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article. HO2S is located on exhaust pipe, behind catalytic converter. ECM is located behind glove box. see scheme 2 If wiring harness and electrical connectors are okay, go to next step. If wiring harness or electrical connector is defective, repair as necessary.
3. With hand-held tester or scan tool still connected to DLC3, start engine and warm engine to normal operating temperature. Monitor HO2S output voltage while quickly accelerating engine to 4000 RPM 3 consecutive times. Output voltage should fluctuate from 0.40 volt or less to 0.50 volt or more. If output voltage is within specification, go to step 8. If output voltage is not within specification, go to next step.
4. Turn ignition off. Disconnect HO2S 4-pin connector. (Scheme 59)& (Scheme 61). Measure resistance between HO2S 4-pin connector terminals No. 2 (+B) and No. 1 (HT). Make note of measurement. Then, measure resistance between HO2S 4-pin connector terminals No. 1 (HT) and No. 4 (E1). See «HO2S HEATER RESISTANCE SPECIFICATIONS»(ref-151976-S24001383152003081100000). If resistance is within specification, go to next step. If resistance is not within specification, replace HO2S. See «HEATED OXYGEN SENSOR»(ref-151984-S41146403752003010900000) under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.
5. Remove EFI relay from engine room relay box. (Scheme 59) Test relay. See EFI RELAY under «MODULES, MOTORS, RELAYS & SOLENOIDS»(ref-151979-S10779012602003010900000) in SYSTEM & COMPONENT TESTING article. If relay is bad, replace it. If relay is Ok, reinstall relay and go to next step.
6. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2 Check continuity between ECM and HO2S connectors at terminals listed below. (Scheme 58)and (Scheme 59). ECM 35-pin connector E5 terminal No. 5 (HT1B) and HO2S (Bank 1 Sensor 2) terminal No. 1. Continuity should exist. ECM 35-pin connector E5 terminal No. 29 (OX1B) and HO2S (Bank 1 Sensor 2) terminal No. 3. Continuity should exist. ECM 35-pin connector E5 terminal No. 25 (HT2B) and HO2S (Bank 2 Sensor 2) terminal No. 1. Continuity should exist. ECM 35-pin connector E5 terminal No. 21 (OX2B) and HO2S (Bank 2 Sensor 2) terminal No. 3. Continuity should exist. ECM 35-pin connector E5 terminal No. 5 (HT1B) and body ground. Continuity should not exist. ECM 35-pin connector E5 terminal No. 29 (OX1B) and body ground. Continuity should not exist. ECM 35-pin connector E5 terminal No. 25 (HT2B) and body ground. Continuity should not exist. ECM 35-pin connector E5 terminal No. 21 (OX2B) and body ground. Continuity should not exist.
7. If continuity is as specified, replace HO2S. See «HEATED OXYGEN SENSOR»(ref-151984-S41146403752003010900000) under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article. If continuity is not as specified, repair wiring as necessary. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article.
8. Using Toyota hand-held tester or scan tool, clear DTCs from ECM. Perform test drive confirmation and then go to next step. See «TEST DRIVE CONFIRMATION»(ref-151976-S24216472672003081100000).
9. Recheck for DTCs. If DTCs P0136 and/or P0156 does not exist, go to next step. If DTCs P0136 and/or P0156 exists, replace HO2S. See «HEATED OXYGEN SENSOR»(ref-151984-S41146403752003010900000) under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.
10. Verify if vehicle ran out of fuel. If vehicle ran out of fuel, DTCs P0136 and/or P0156 was caused by the vehicle running out of fuel. If vehicle did not run out of fuel, problem is intermittent. Check for defective connections or intermittent problem in wiring. ECM is located behind glove box. see scheme 2

1. 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.
2. Connect hand-held tester to Data Link Connector (DLC3) at driver's side of instrument panel. see scheme 1 Switch hand-held tester from NORMAL mode to CHECK mode.
3. 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.
4. 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.
5. 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.

1. Check for any loose or defective PCV valve hose connections. PCV valve is located on top of passenger's side valve cover near front corner of valve cover. If PCV valve hose connections are okay, go to next step. If PCV valve hose connections are defective, repair or replace components as necessary.
2. Ensure engine oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem does not exist, go to next step. If problem exists, repair as necessary.
3. Check operation of fuel injectors. See «FUEL CONTROL»(ref-151979-S22215092702003010900000) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. Fuel injector volume should be.20-.25 oz. (60-73 cc) within 15 seconds and difference in volume between each fuel injector should be less than.04 oz. (13 cc). Fuel injectors should not leak more than one drop every 12 minutes. If fuel injectors are okay, go to next step. If fuel injectors are defective, replace fuel injectors as necessary.
4. Check Mass Airflow (MAF) meter and Engine Coolant Temperature (ECT) sensor. MAF meter may also be referred to as airflow meter. See «AIRFLOW METER»(ref-151979-S27373878712003010900000) and «ENGINE COOLANT TEMPERATURE SENSOR»(ref-151979-S16108789692003010900000) under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - V6 & V8 article. If MAF meter and ECT sensor are okay, go to next step. If MAF meter or ECT sensor is defective, replace components as necessary. See «MASS AIRFLOW METER»(ref-151984-S24928640612003010900000) and «ENGINE COOLANT TEMPERATURE SENSOR»(ref-151984-S40345071782003010900000) under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.
5. Check ignition system by performing spark test. See «SPARK TEST»(ref-151953-S22929264732003010900000) under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If ignition system operates properly and spark exists, go to next step. If ignition system does not operate properly and spark does not exist, repair ignition system as necessary.
6. Check fuel pressure. See «FUEL PRESSURE»(ref-151953-S33614114892003010900000) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, repair fuel system as necessary.
7. Check exhaust system for leaks. If no exhaust leak exists, go to next step. If exhaust leak exists, repair exhaust system as necessary.
8. Connect Toyota hand-held tester or scan tool to Data Link Connector (DLC3) at driver's side of instrument panel. see scheme 1 Start engine and maintain engine speed at 2500 RPM for about 90 seconds to fully warm oxygen sensor. Allow engine to idle.
9. Using hand-held tester or scan tool, monitor oxygen sensor output voltage with engine idling. Heated oxygen sensor output should alternate between less than 0.4 volt and more than 0.55 volt. If voltage is as specified, go to step 17. If voltage is not as specified, go to next step.
10. Turn ignition off. Disconnect HO2S 4-pin connector. (Scheme 59) Measure resistance between HO2S 4-pin connector terminals No. 2 (+B) and No. 1 (HT). Make note of measurement. Then, measure resistance between HO2S 4-pin connector terminals No. 1 (HT) and No. 4 (E1). See «HO2S HEATER RESISTANCE SPECIFICATIONS»(ref-151976-S24001383152003081100000). If resistance is within specification, go to next step. If resistance is not within specification, replace HO2S. See «HEATED OXYGEN SENSOR»(ref-151984-S41146403752003010900000) under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.
11. Remove EFI relay from engine room relay box. (Scheme 59) Test relay. See EFI RELAY under «MODULES, MOTORS, RELAYS & SOLENOIDS»(ref-151979-S10779012602003010900000) in SYSTEM & COMPONENT TESTING article. If relay is bad, replace it. If relay is Ok, reinstall relay and go to next step.
12. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2 Check continuity between ECM and HO2S connectors at terminals listed below. (Scheme 58)and (Scheme 59). ECM 35-pin connector E5 terminal No. 5 (HT1B) and HO2S (Bank 1 Sensor 2) terminal No. 1. Continuity should exist. ECM 35-pin connector E5 terminal No. 29 (OX1B) and HO2S (Bank 1 Sensor 2) terminal No. 3. Continuity should exist. ECM 35-pin connector E5 terminal No. 25 (HT2B) and HO2S (Bank 2 Sensor 2) terminal No. 1. Continuity should exist. ECM 35-pin connector E5 terminal No. 21 (OX2B) and HO2S (Bank 2 Sensor 2) terminal No. 3. Continuity should exist. ECM 35-pin connector E5 terminal No. 5 (HT1B) and body ground. Continuity should not exist. ECM 35-pin connector E5 terminal No. 29 (OX1B) and body ground. Continuity should not exist. ECM 35-pin connector E5 terminal No. 25 (HT2B) and body ground. Continuity should not exist. ECM 35-pin connector E5 terminal No. 21 (OX2B) and body ground. Continuity should not exist.
13. If continuity is as specified, replace HO2S. Then, go to next step. See «HEATED OXYGEN SENSOR»(ref-151984-S41146403752003010900000) under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article. If continuity is not as specified, repair wiring as necessary. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article.
14. Using Toyota hand-held tester or scan tool, clear DTCs from ECM. Perform test drive confirmation and then go to next step. See «TEST DRIVE CONFIRMATION»(ref-151976-S32134211632003010900000).
15. Recheck for DTCs. If DTCs P0171, P0172, P0174 and/or P0175 does not exist, go to next step. If DTCs P0171, P0172, P0174 and/or P0175 exist, replace ECM. ECM is located behind glove box. see scheme 2 Then, perform test drive confirmation and then go to next step. See «TEST DRIVE CONFIRMATION»(ref-151976-S32134211632003010900000).
16. Verify if vehicle ran out of fuel. If vehicle ran out of fuel, DTCs P0171, P0172, P0174 and/or P0175 was caused by the vehicle running out of fuel. If vehicle did not run out of fuel, problem is intermittent. Check for defective connections or intermittent problem in wiring. ECM is located behind glove box. see scheme 2
17. Using Toyota hand-held tester or scan tool, clear DTCs from ECM. Perform test drive confirmation and then go to next step. See «TEST DRIVE CONFIRMATION»(ref-151976-S32134211632003010900000).
18. Recheck for DTCs. If DTCs P0171, P0172, P0174 and/or P0175 does not exist, go to step 20. If DTCs P0171, P0172, P0174 and/or P0175 exist, replace HO2S. See «HEATED OXYGEN SENSOR»(ref-151984-S41146403752003010900000) under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article. Then, go to next step.
19. Recheck for DTCs. If DTCs P0171, P0172, P0174 and/or P0175 does not exist, go to next step. If DTCs P0171, P0172, P0174 and/or P0175 exist, replace ECM. ECM is located behind glove box. see scheme 2 Then, perform test drive confirmation and then go to next step. See «TEST DRIVE CONFIRMATION»(ref-151976-S32134211632003010900000).
20. Verify if vehicle ran out of fuel. If vehicle ran out of fuel, DTCs P0171, P0172, P0174 and/or P0175 was caused by the vehicle running out of fuel. If vehicle did not run out of fuel, problem is intermittent. Check for defective connections or intermittent problem in wiring. see scheme 2

When the engine is cranked, current flows from ECM to the starter relay coil and also current flows to ECM (START) signal terminal. When the START signal and ENGINE RUNNING signal from CKP are input to the ECM, transistor No. 1 (internal in ECM) is turned ON, current flows to the coil of the circuit opening relay, the relay switches on, power is supplied to the fuel pump, and the fuel pump operates. While the ENGINE RUNNING signal from CKP is generated, the ECM keeps transistor No. 1 (internal in ECM) ON (circuit opening relay ON) and the fuel pump keeps operating. The fuel pump speed is controlled at two levels (high speed or low speed) by the condition of the engine (starting, light load, heavy load). When the engine starts, transistor No. 2 (internal in ECM) is OFF, so the fuel pump relay closes and battery positive voltage is applied directly to the fuel pump. The fuel pump operates at high speed. After the engine starts during idling or light loads, since transistor No. 2 goes ON, power is supplied to the fuel pump via the fuel pump resistor. The fuel pump operates at low speed. DTC will set when an open or short circuit in fuel pump relay has been detected. Possible causes are

1. Open or short in fuel pump relay circuit.
2. Defective fuel pump relay.
3. ECM.

This DTC diagnosis & repair procedure assumes the premise that the engine starts normally. If DTC is present and a no start condition exists, proceed to BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article.

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

1. Remove glove box and ECM, leaving ECM connectors connected. ECM is located behind glove box. see scheme 2 Backprobing, measure voltage between ECM 34-pin connector E4 terminal No. 33 (+) (Green/Red wire) and ECM 32-pin connector E6 terminal No. 1 (-) (Brown wire). With shift indicator in P or N position and ignition switch in START position, voltage should be 9-14 volts. With ignition in ON position, voltage should be 0-3 volts. (Scheme 58) If voltage is as specified, replace ECM. If voltage is not as specified, go to next step.
2. Remove the fuel pump relay from the engine room relay box. (Scheme 62) Inspect the fuel pump relay. See «FUEL PUMP RELAY»(ref-151979-S19087612892003010900000) under MODULES, MOTORS, RELAYS & SOLENOIDS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If relay is Ok, go to next step. If relay is bad, replace relay.
3. Disconnect ECM 34-pin connector E4. Check continuity between fuel pump relay socket terminal No. 1 and ECM 34-pin connector terminal No. 33 (Green/Red wire). Continuity should exist. Then, check continuity between fuel pump relay socket terminal No. 1 and ground. Continuity should not exist. If continuity is as specified, replace ECM. If continuity is not as specified, repair or replace harness wires or connectors as necessary.

Scheme 62

1. 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 (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.
2. 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.
3. Allow engine to idle for at least 3 1/2 minutes and then drive vehicle at specified engine speeds for specified amount of time. See «DRIVING PATTERN»(ref-151976-S32044674282003010900000). If NOT using scan tool, turn ignition off after symptom is simulated the first time, then repeat test drive again (two 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 (one trip detection logic). Be careful not to turn ignition off. Doing so switches scan tool diagnosis system from CHECK mode to NORMAL mode, erasing all DTCs and FREEZE FRAME data. Go to next step. DRIVING PATTERN Engine RPM Specified Time 1000 3 Minutes Or More 2000 1 1/2 Minutes Or More 3000 1 Minute Or More
4. Check for misfire or not by monitoring DTC and freeze frame data. Record any data. Turn ignition off and wait a minimum of 5 seconds. NOTE: If any other DTC(s) are recorded, perform troubleshooting for them first, then recheck.

Scheme 63

1. Check for any loose or defective PCV valve hose connections. PCV valve is located on top of passenger's side valve cover near front corner of valve cover. If PCV valve hose connections are okay, go to next step. If PCV valve hose connections are defective, repair or replace components as necessary.
2. Check vacuum hoses for leaks, restrictions, poor connections and proper routing. See «VACUUM DIAGRAMS»(ref-151982) article for proper vacuum hose routing. Also, check engine wiring harness and electrical connectors for damage or poor connections. If no problems exist, go to next step. If problem exists, repair as necessary and perform «TEST DRIVE CONFIRMATION»(ref-151976-S39686713102003010900000).
3. Connect Toyota hand-held tester or scan tool to Data Link Connector (DLC3) at driver's side of instrument panel. see scheme 1 Check number of MISFIRE COUNTS in the DATA LIST for all cylinders. If there is a high misfire count on 1 or 2 cylinders only, go to next step. If there is a high misfire count for more than 3 cylinders, go to step 13.
4. Remove spark plug for misfiring cylinder. Ensure no carbon deposits exist, spark plug is not fouled and spark plug gap is.043" (1.10 mm). Check ignition system by performing spark test on misfiring cylinder. Disconnect each fuel injector connector while performing spark test. See «SPARK TEST»(ref-151953-S22929264732003010900000) under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If ignition system operates properly and spark exists, go to step 8. If ignition system does not operate properly and spark does not exist, go to next step.
5. Replace spark plugs and check ignition system by performing spark test again. Disconnect each fuel injector connector while performing spark test. See «SPARK TEST»(ref-151953-S22929264732003010900000) under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If ignition system operates properly and spark exists, perform «TEST DRIVE CONFIRMATION»(ref-151976-S39686713102003010900000). If ignition system does not operate properly and spark does not exist, go to next step.
6. Turn ignition off. Remove glove box for access to ECM with connectors. see scheme 2 Disconnect all 8 ignition coil 4-pin connectors and ECM 34-pin connector E4. (Scheme 58)& (Scheme 64). Check continuity between ignition coil 4-pin connector terminal and ECM 34-pin connector E4 terminals. See «IDENTIFYING ECM (IGF) TO IGNITION COILS TERMINALS»(ref-151976-S12148583712003081200000) for appropriate ignition coil and ECM 34-pin connector E4 terminal selections. Continuity should exist. Then, check continuity between body ground and ECM 34-pin connector E4 terminals No. 23 (Red/White wire) and No. 24 (Red/Yellow wire) individually. There should be no continuity. Go to next step. IDENTIFYING ECM (IGF) TO IGNITION COILS TERMINALS Ignition Coil No. (1) (3) ECM 34-Pin Connector E4 Terminal No. Wire Color 1 (2) No. 24 Red/Yellow 2 (2) No. 23 Red/White 3 (2) No. 23 Red/White 4 (2) No. 24 Red/Yellow 5 (2) No. 23 Red/White 6 (2) No. 24 Red/Yellow 7 (2) No. 24 Red/Yellow 8 (2) No. 23 Red/White (1) Ignition coil No. 1 is front ignition coil on passenger's side of engine. Ignition coil No. 2 is front ignition coil on driver's side of engine. Ignition coils No. 1, 3, 5 and 7 are on passenger's side of engine. Ignition coils No. 2, 4, 6 and 8 are on driver's side of engine. (2) For all continuity checks, use ignition coil 4-pin connector terminal No. 2. (3) For ECM electrical connector terminal identification (Scheme 58)
7. Check continuity between ignition coil 4-pin connector terminal and ECM 34-pin connector E4 terminals. See «IDENTIFYING ECM (IGT) TO IGNITION COILS TERMINALS»(ref-151976-S38731516182003081200000) for appropriate ignition coil and ECM 34-pin connector E4 terminal selections. Continuity should exist. Then, check continuity between body ground and ignition coil 4-pin connector terminals No. 3, individually. There should be no continuity. If continuity is as specified, replace ignition coil(s) assembly. Then, perform «TEST DRIVE CONFIRMATION»(ref-151976-S39686713102003010900000). If continuity is not as specified, repair or replace harness and/or connectors as necessary. Then, perform «TEST DRIVE CONFIRMATION»(ref-151976-S39686713102003010900000). IDENTIFYING ECM (IGT) TO IGNITION COILS TERMINALS Ignition Coil No. (1) (2) ECM 34-Pin Connector E4 Terminal No. Wire Color 1 (3) No. 9 Light Green 2 (3) No. 8 Light Green/Black 3 (3) No. 25 Blue/White 4 (3) No. 11 Blue/Yellow 5 (3) No. 12 Black/Blue 6 (3) No. 26 Green 7 (3) No. 13 Green/White 8 (3) No. 10 Green/Black (1) Ignition coil No. 1 is front ignition coil on passenger's side of engine. Ignition coil No. 2 is front ignition coil on driver's side of engine. Ignition coils No. 1, 3, 5 and 7 are on passenger's side of engine. Ignition coils No. 2, 4, 6 and 8 are on driver's side of engine. (2) For ECM electrical connector terminal identification (Scheme 58) (3) For all continuity checks, use ignition coil 4-pin connector terminal No. 3.
8. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2 Turn ignition on. With negative (-) probe of voltmeter on ECM 34-pin connector E4 terminal No. 7 (EO1) (White/Black wire), place positive (+) probe and check voltage at appropriate ECM connector (fuel injector driver) terminal. See «IDENTIFYING ECM FUEL INJECTOR DRIVER TERMINALS»(ref-151976-S21860279412003010900000) for ECM injector driver circuit terminal selections. For ECM electrical connector terminal identification (Scheme 58)& (Scheme 64). If voltage is not 9-14 volts at fuel injector driver terminal, go to next step. If voltage is 9-14 volts at fuel injector driver terminal, go to step 11. NOTE: With engine idling, using same connections as described above, an oscilloscope can be used to show each injector's waveform pattern. Fuel injector signal waveform pattern and fuel injector duration signal waveform pattern should be properly displayed within proper intervals. (Scheme 63) IDENTIFYING ECM FUEL INJECTOR DRIVER TERMINALS Fuel Injector No. (1) ECM Electrical Connector & Terminal (2) Wire Color 1 E4 Terminal No. 1 Red/Blue 2 E4 Terminal No. 2 Blue 3 E4 Terminal No. 3 White 4 E4 Terminal No. 4 Yellow 5 E4 Terminal No. 5 Green 6 E5 Terminal No. 3 Red 7 E6 Terminal No. 6 White 8 E6 Terminal No. 5 Brown (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, 5 and 7 are on passenger's side of engine. Fuel injectors No. 2, 4, 6 and 8 are on driver's side of engine. (2) For ECM electrical connector terminal identification (Scheme 58)
9. Disconnect electrical connector at fuel injector for misfiring cylinder. Using ohmmeter, check resistance between electrical terminals on fuel injector. Resistance should be about 13.4-14.2 ohms at 68°F (20°C). If resistance is within specification, go to next step. If resistance is not within specification, replace fuel injector. See «FUEL RAILS & FUEL INJECTORS»(ref-151984-S24404518332003010900000) under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.
10. Disconnect ECM connectors E4, E5, and E6. Check continuity between each injector connector terminal No. 2 and ECM connector. See «IDENTIFYING ECM FUEL INJECTOR DRIVER TERMINALS»(ref-151976-S21860279412003010900000) for terminal selections. Here, continuity should exist. Then, check continuity between each injector connector terminal No. 2 and body ground. Continuity should not exist. Check that continuity exists between ignition switch connector terminal No. 6 and injector connector terminal No. 1. If continuity is not as specified, repair as necessary. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article. If continuity is as specified, go to next step.
11. Check operation of fuel injector for misfiring cylinder. See «FUEL CONTROL»(ref-151979-S22215092702003010900000) under FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. Fuel injector volume should be 0.20-0.25 oz. (60-73 cc) within 15 seconds and difference in volume between each fuel injector should be less than 0.04 oz. (13 cc). Fuel injectors should not leak more than one drop every 12 minutes. If fuel injectors are okay, go to next step. If fuel injectors are defective, replace fuel injectors as necessary.
12. Check engine compression on misfiring cylinder. See «ENGINE MECHANICAL»(ref-151949-S00997933432003010900000) under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. Check valve clearance on misfiring cylinder. See «V8 VALVE CLEARANCE»(ref-151949-S01204936222003010900000) under ENGINE MECHANICAL in ON-VEHICLE ADJUSTMENTS - V6 & V8 article.
13. Check valve timing belt for loose or jumped teeth. See appropriate article in ENGINES. Repair engine as necessary. If valve timing and timing belt are OK, go to next step.
14. Check fuel pressure. See «FUEL PRESSURE»(ref-151953-S33614114892003010900000) under FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If fuel pressure is within specification, go to next step. If fuel pressure is not within specification, repair fuel system as necessary.
15. Connect Toyota hand-held tester or scan tool to Data Link Connector (DLC3) at driver's side of instrument panel. see scheme 1 Start engine and maintain engine speed at 2500 RPM for about 90 seconds to fully warm the HO2S. Allow engine to idle.
16. Check Intake Air Temperature (IAT ) sensor. See «INTAKE AIR TEMPERATURE SENSOR»(ref-151979-S11749446942003010900000) under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - V6 & V8 article. If IAT sensor is okay, go to next step. If IAT sensor is defective, replace components as necessary (IAT and MAF are combined into one unit). See «AIRFLOW METER»(ref-151984-S24928640612003010900000) under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.
17. Check Mass Airflow (MAF) meter. MAF meter may also be referred to as airflow meter. See «AIRFLOW METER»(ref-151979-S27373878712003010900000) under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - V6 & V8 article. If MAF meter is okay, go to next step. If MAF meter is defective, replace components as necessary. See «AIRFLOW METER»(ref-151984-S24928640612003010900000) under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.
18. Check Engine Coolant Temperature (ECT) sensor. See «ENGINE COOLANT TEMPERATURE SENSOR»(ref-151979-S16108789692003010900000) under ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - V6 & V8 article. If ECT sensor is okay, go to next step. If ECT sensor is defective, replace components as necessary. See «ENGINE COOLANT TEMPERATURE SENSOR»(ref-151984-S40345071782003010900000) under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.
19. Connect Toyota hand-held tester or scan tool to Data Link Connector (DLC3) at driver's side of instrument panel. see scheme 1 Check number of MISFIRE COUNTS in the DATA LIST for all cylinders. If there is a high misfire count on 1 or 2 cylinders only, go to next step. If there is a high misfire count for more than 3 cylinders, go to step 13 and recheck.
20. Verify if vehicle ran out of fuel. If vehicle ran out of fuel, DTC P0300 and DTCs P0301-P0308 was caused by the vehicle running out of fuel. If vehicle did not run out of fuel, problem is intermittent. Check for defective connections or intermittent problem in wiring. ECM is located behind glove box. see scheme 2

Scheme 64

1. Check resistance of crankshaft position sensor. See «CRANKSHAFT POSITION SENSOR»(ref-151953-S32927524702003010900000) under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. Crankshaft position sensor is located at front of engine, just above crankshaft pulley. (Scheme 68) If crankshaft position sensor is okay, go to next step. If crankshaft position sensor is defective, replace crankshaft position sensor. See «CRANKSHAFT POSITION SENSOR»(ref-151984-S30853055372003010900000) under IGNITION SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.
2. Remove glove box to gain access to ECM connectors with ECM attached. see scheme 2 Check continuity between crankshaft position sensor 2-pin connector terminal No. 1 and ECM 32-pin connector E6 terminal No. 25 (NE+) (Blue wire). (Scheme 58), (Scheme 65) & (Scheme 66). Then, check continuity between crankshaft position sensor 2-pin connector terminal No. 2 and ECM 32-pin connector E6 terminals No. 24 (NE-) (Yellow wire). Continuity should exist. Check that continuity does not exist between ground and either wire. If continuity is as specified, go to next step. If continuity is not as specified, repair or replace wires and/or connectors as necessary.
3. Check the installation of crankshaft position sensor, tighten if necessary. If the installation is Ok, go to next step.
4. Remove crankshaft position sensor. See «CRANKSHAFT POSITION SENSOR»(ref-151984-S30853055372003010900000) under IGNITION SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article. Remove and inspect crankshaft position sensor plate No. 1 teeth for damage. If crankshaft position sensor or signal plate is damaged, replace components as necessary. If crankshaft position sensor and signal plate are okay, replace ECM.

Scheme 65

Scheme 66

Scheme 67

Scheme 68

1. Disconnect electrical connector for camshaft position sensor installed on the camshaft timing pulley LH side.
2. Using ohmmeter, check resistance between electrical terminals on camshaft position sensor. Resistance should be 835-1400 ohms with sensor temperature of 14-122°F (-10-50°C) and 1060-1645 ohms with sensor temperature of 122-212°F (50-100°C). If resistance is within specification, go to next step. If resistance is not within specification, replace camshaft position sensor. See «CAMSHAFT POSITION SENSOR»(ref-151984-S08754480822003010900000) under IGNITION SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.
3. Remove glove box to gain access to ECM connectors with ECM attached. see scheme 2 Check continuity between camshaft position sensor 2-pin connector terminal No. 1 and ECM 32-pin connector E6 terminals No. 27 (G2+) (Black wire). (Scheme 58), (Scheme 65) & (Scheme 69). Then, check continuity between camshaft position sensor 2-pin connector terminal No. 2 and ECM 32-pin connector E6 terminals No. 32 (G2-) (White wire). Continuity should exist. Check that continuity does not exist between ground and either wire. If continuity is as specified, go to next step. If continuity is not as specified, repair or replace wires and/or connectors as necessary.
4. Inspect installation of camshaft position sensor for looseness. Tighten if necessary. If installation is Ok, go to next step.
5. Remove camshaft position sensor. See «CAMSHAFT POSITION SENSOR»(ref-151984-S08754480822003010900000) under IGNITION SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article. Inspect camshaft LH pulley sub assembly for tooth damage on signal plate. If camshaft position sensor or signal plate is damaged, replace components as necessary. If camshaft position sensor and signal plate are okay, replace ECM.

Scheme 69

1. Remove spark plug for misfiring cylinder. Ensure no carbon deposits exist, spark plug is not fouled and spark plug gap is.043" (1.10 mm). Check ignition system by performing spark test on misfiring cylinder. Disconnect each fuel injector connector while performing spark test. See «SPARK TEST»(ref-151953-S22929264732003010900000) under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If ignition system operates properly and spark exists, go to next step. If ignition system does not operate properly and spark does not exist, go to step 4.
2. Turn ignition off. Remove glove box for access to ECM with connectors. see scheme 2 Disconnect all 8 ignition coil 4-pin connectors and ECM 34-pin connector E4. (Scheme 58)& (Scheme 64). Check continuity between ignition coil 4-pin connector terminal and ECM 34-pin connector E4 terminals. See «IDENTIFYING ECM (IGF) TO IGNITION COILS TERMINALS»(ref-151976-S41300971462003081200000) for appropriate ignition coil and ECM 34-pin connector E4 terminal selections. Continuity should exist. Then, check continuity between body ground and ECM 34-pin connector E4 terminals No. 23 (Red/White wire) and No. 24 (Red/Yellow wire) individually. There should be no continuity. If continuity is as specified, go to next step. If continuity is not as specified, repair or replace wires and/or connectors as necessary. IDENTIFYING ECM (IGF) TO IGNITION COILS TERMINALS Ignition Coil No. (1) (3) ECM 34-Pin Connector E4 Terminal No. Wire Color 1 (2) No. 24 Red/Yellow 2 (2) No. 23 Red/White 3 (2) No. 23 Red/White 4 (2) No. 24 Red/Yellow 5 (2) No. 23 Red/White 6 (2) No. 24 Red/Yellow 7 (2) No. 24 Red/Yellow 8 (2) No. 23 Red/White (1) Ignition coil No. 1 is front ignition coil on passenger's side of engine. Ignition coil No. 2 is front ignition coil on driver's side of engine. Ignition coils No. 1, 3, 5 and 7 are on passenger's side of engine. Ignition coils No. 2, 4, 6 and 8 are on driver's side of engine. (2) For all continuity checks, use ignition coil 4-pin connector terminal No. 2. (3) For ECM electrical connector terminal identification (Scheme 58)
3. Reconnect ECM 34-pin connector E4. Turn ignition on. Backprobing, measure voltage between ECM 34-pin connector E4 terminal No. 24 (+) (IGF1) and ECM 32-pin connector E6 terminal No. 1 (-) (Red/Yellow wire). Then, measure voltage between ECM 34-pin connector E4 terminal No. 23 (+) (IGF2) and ECM 32-pin connector E6 terminal No. 1 (-) (Red/White wire). Voltage should be 4.5-5.5 volts at both checks. If voltage is not as specified, replace ECM. If voltage is as specified, replace ignition coil(s).
4. Remove glove box to gain access to ECM connectors. see scheme 2 Disconnect all 8 ignition coil 4-pin connectors and ECM 34-pin connector E4. (Scheme 58)and (Scheme 64). Check continuity between ignition coil 4-pin connector terminal and ECM 34-pin connector E4 terminals. See «IDENTIFYING ECM (IGT) TO IGNITION COILS TERMINALS»(ref-151976-S16484715412003081200000) for appropriate ignition coil and ECM 34-pin connector E4 terminal selections. Continuity should exist. Then, check continuity between body ground and each ignition coil 4-pin connector terminal No. 3, individually. There should be no continuity. If continuity is as specified, go to next step. If continuity is not as specified, repair or replace harness and/or connectors as necessary. IDENTIFYING ECM (IGT) TO IGNITION COILS TERMINALS Ignition Coil No. (1) (2) ECM 34-Pin Connector E4 Terminal No. Wire Color 1 (3) No. 9 Light Green 2 (3) No. 8 Light Green/Black 3 (3) No. 25 Blue/White 4 (3) No. 11 Blue/Yellow 5 (3) No. 12 Black/Blue 6 (3) No. 26 Green 7 (3) No. 13 Green/White 8 (3) No. 10 Green/Black (1) Ignition coil No. 1 is front ignition coil on passenger's side of engine. Ignition coil No. 2 is front ignition coil on driver's side of engine. Ignition coils No. 1, 3, 5 and 7 are on passenger's side of engine. Ignition coils No. 2, 4, 6 and 8 are on driver's side of engine. (2) For ECM electrical connector terminal identification (Scheme 58) (3) For all continuity checks, use ignition coil 4-pin connector terminal No. 3.
5. Reconnect ECM 34-pin connector E4. Turn ignition on. Backprobing, measure voltage while engine is being cranked, between ECM 34-pin connector E4 (IGT+) terminals and ECM 32-pin connector E6 terminal No. 1 (-) (Red/Yellow wire). See «IDENTIFYING ECM (IGT) TO IGNITION COILS TERMINALS»(ref-151976-S16484715412003081200000) for ECM terminal selections. Voltage should be more than 0.1 volt and less than 4.5 volts at all 8 checks. If voltage is not as specified, replace ECM. If voltage is as specified, go to next step. NOTE: During cranking or idling, check the waveform using an oscilloscope at the same terminals checked above. ECM IGT and IGF signal waveform patterns should be properly displayed. (Scheme 70)
6. Ignition still on, measure voltage between ground and suspect ignition coil 4-pin connector terminal No. 1 (Black/Red wire). (Scheme 64) Voltage should be between 9-14 volts. If voltage is as specified, replace ignition coil(s). If voltage is not as specified, go to next step.
7. Turn ignition off. Disconnect ignition switch 8-pin connector. Check continuity between suspect ignition coil 4-pin connector terminal No. 1 (Black/Red wire) and ignition switch 8-pin connector terminal No. 6 (IG2). Continuity should exist. Then, check continuity between body ground and ignition switch 8-pin connector terminal No. 6 (IG2). Continuity should not exist. If continuity is as specified, replace ignition coil(s). If continuity is not as specified, repair or replace harness wire and/or connector as necessary.

Scheme 70

The ECM compares the waveform of the heated oxygen sensor located before the catalyst with the waveform of the heated oxygen sensor located after the catalyst to determine whether or not the catalyst performance has deteriorated. The data input to ECM keeps the HO2S (Sensor 1) repeatedly changing back and forth from rich to lean. If the catalyst is functioning normally, the HO2S (Sensor 2) after the catalyst switches back and forth between rich and lean much more slowly than the HO2S (Bank 1) before the catalyst. But when both HO2S (Sensor 1 & 2) change at a similar rate, it indicates that the catalyst performance has deteriorated. DTC is set when HO2S (Sensor 1 & 2) have nearly the same waveform pattern after engine and catalytic converter are at normal operating temperature and vehicle is driven. Possible causes are

1. Exhaust system leak.
2. Defective HO2S.
3. Defective 3-way catalytic converter (in exhaust manifold).

This DTC uses two-trip detection logic. Using Toyota hand-held tester or scan tool, read FREEZE FRAME data. Freeze frame data records engine conditions when malfunction is detected.

1. Using Toyota hand-held tester or scan tool, check for any other DTCs. If only DTCs P0420 and/or P0430 exists, go to next step. If other DTCs exist, diagnose and repair those DTCs first and then retest.
2. Check exhaust system for leaks. If no exhaust leak exists, go to next step. If exhaust leak exists, repair exhaust system as necessary.
3. Turn ignition off. Disconnect HO2S 4-pin connector. (Scheme 59) Measure resistance between HO2S 4-pin connector terminals No. 2 (+B) and No. 1 (HT). Make note of measurement. Then, measure resistance between HO2S 4-pin connector terminals No. 1 (HT) No. 4 (E1). See «HO2S HEATER RESISTANCE SPECIFICATIONS»(ref-151976-S27379541872003081300000). If resistance is within specification, replace TWC (in exhaust manifold LH or RH). If resistance is not within specification, replace HO2S. See «HEATED OXYGEN SENSOR»(ref-151984-S41146403752003010900000) under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article. HO2S HEATER RESISTANCE SPECIFICATIONS Terminals No. Resistance in Ohms @ 68F (20C) 1 (HT) & 2 (B+) 11-16 1 (HT) & 4 (E1) No Continuity

EVAP Leak Test

1. Connect hand-held tester or enhanced OBD II scanner to Data Link Connector (DLC3) at driver's side of instrument panel. see scheme 1
2. Select ENHANCED OBD II/SYSTEM CHECK/EVAP SYS CHECK or EVAP LEAK TEST mode on hand-held tester.
3. If any changes do not occur within one minute after pressing EVAP LEAK TEST, remove and reinstall fuel tank cap, then perform EVAP LEAK TEST again.
4. If a leak is detected, or if DTCs P0441, P0442 and P0446 are output simultaneously, repeat leak test after repair. If no leak is detected at this time, EVAP system is okay.

Confirmation Readiness Test

To run EVAP monitor (Scheme 71)and (Scheme 72).

Scheme 71

Scheme 72

For diagnosis and repair (Scheme 73)- (Scheme 90). For wiring diagram (Scheme 91)

Scheme 73

Scheme 74

Scheme 75

Scheme 76

Scheme 77

Scheme 78

Scheme 79

Scheme 80

Scheme 81

Scheme 82

Scheme 83

Scheme 84

Scheme 85

Scheme 86

Scheme 87

Scheme 88

Scheme 89

Scheme 90

Scheme 91

1. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2 Turn ignition on. Using voltmeter, check voltage between ECM 34-pin connector E4 terminals No. 18 (+) (Black/Red wire) and No. 28 (-) (Brown wire). (Scheme 58) This is the VC+ and E2- terminals on ECM. Voltage should be 4.5-5.5 volts. If voltage is within specification, go to next step. If voltage is not within specification, replace ECM.
2. Turn ignition off. Backprobing, connect voltmeter between ECM 31-pin connector E8 terminal No. 21 (Orange wire) and ECM 34-pin connector E4 terminal No. 28 (Brown wire). (Scheme 58) This is the E2 and PTNK terminals on ECM. Disconnect vacuum hose from vapor pressure sensor. Turn ignition on and note voltage. Voltage should be 2.9-3.7 volts. Turn ignition off. Then, connect vacuum/pressure pump to vapor pressure sensor vacuum port. Apply 1.18 in. Hg vacuum to sensor. Turn ignition on and measure voltage. Voltage should be less than 0.5 volt. If voltage is not as specified, go to next step. If voltage is as specified, replace ECM.
3. Turn ignition off. Disconnect vapor pressure sensor 3-pin connector and ECM 31-pin connector E8 and ECM 34-pin connector E4. Vapor pressure sensor is located on top of fuel pump assembly on top of fuel tank and contains a 3-pin electrical connector with Black/Red, Orange and Brown wires. (Scheme 92), (Scheme 93) and (Scheme 94). Check continuity between ECM E4 connector terminal No. 28 and VPS 3-pin connector terminal No. 1, between ECM E8 connector terminal No. 21 and VPS 3-pin connector terminal No. 2, and between ECM E4 connector terminal No. 18 and VPS 3-pin connector terminal No. 3. Continuity should exist at all 3 checks. Then, check that continuity does not exist between ground and VPS 3-pin connector terminals No. 2 and 3 individually. If continuity is as specified, replace vapor pressure sensor. See «VAPOR PRESSURE SENSOR»(ref-151984-S32872100962003010900000) under EMISSION SYSTEMS & SUB-SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article. If continuity is not as specified, repair or replace wires and/or connectors as necessary.

Scheme 92

Scheme 93

Scheme 94

1. Test drive vehicle and check operation of speedometer. If speedometer operates properly, go to next step. If speedometer does not operate properly, repair speedometer as necessary. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. Speedometer may not operate, as output signal from VSC ECU and input to combination meter may not be occurring.
2. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2 Raise and support vehicle with one rear wheel off the ground. Place transmission in Neutral.
3. Disconnect ECM 32-pin connector E6 and ECM 35-pin connector E7. (Scheme 58) Turn ignition on. Backprobing, measure voltage between ECM 32-pin connector E6 terminal No. 1 (-) and ECM 35-pin connector E7 terminal No. 17 (+) (Violet/Red wire) while rotating rear wheel. (Scheme 58) This is the SPD terminal on ECM. Voltage should pulse between zero volts and 4.5-5.5 volts. If voltage is within specification, replace ECM. If voltage is not within specification, repair or replace wire and/or connector as necessary. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article.

1. If Toyota hand-held tester is available, go to next step. If Toyota hand-held tester is not available, go to step 6.
2. Check stoplight operation. If stoplights operate properly, go to next step. If stoplights do not operate properly, repair as necessary and retest system. See appropriate EXTERIOR LIGHTS article in ACCESSORIES & EQUIPMENT.
3. Connect hand-held tester to Data Link Connector (DLC3) at driver's side of instrument panel. see scheme 1 Turn ignition on and then turn hand-held tester on.
4. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2 Backprobing, measure voltage between ECM 32-pin connector E6 terminal No. 1 (-) and ECM 35-pin connector E7 terminal No. 12 (+) (Red/Blue wire). This is the ST1- terminal on ECM. Monitor STP signal and ST1- voltage on hand-held tester while depressing and releasing brake pedal. STP signal should indicate ON with brake pedal depressed and OFF with brake pedal released. The ST1- voltage should be below 1.5 volts when pedal is depressed and 7.5-14 volts when pedal is released. If STP signal and ST1- voltage are not as specified, go to next step. If STP signal and ST1- voltage are as specified, problem is intermittent. Check for defective connections or intermittent problem in wiring harness between stoplight switch and ECM, and for intermittent problem with stoplight switch.
5. Disconnect ECM 35-pin connector E7. (Scheme 58) Check continuity between stop light switch 4-pin connector terminal No. 1 and ECM 35-pin connector E7 terminal No. 19. Then, check continuity between stop light switch 4-pin connector terminal No. 4 and ECM 35-pin connector E7 terminal No. 12. Continuity should exist. Check that continuity does not exist between ground and stop light switch 4-pin connector terminals No. 1 and 4 individually. If continuity is as specified, replace ECM. If continuity is not as specified, repair or replace wires and/or connectors as necessary.
6. Check stoplight operation. If stoplights operate properly, go to next step. If stoplights do not operate properly, repair as necessary and retest system. See appropriate EXTERIOR LIGHTS article in ACCESSORIES & EQUIPMENT.
7. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2 Backprobing, measure voltage between ECM 32-pin connector E6 terminal No. 1 (-) and ECM 35-pin connector E7 terminal No. 12 (+) (Red/Blue wire). This is the ST1- terminal on ECM. The ST1- voltage should be below 1.5 volts when pedal is depressed and 7.5-14 volts when pedal is released. Then, backprobing, measure voltage between ECM 32-pin connector E6 terminal No. 1 (-) and ECM 35-pin connector E7 terminal No. 19 (+) (Green/Yellow wire). This is the STP terminal on ECM. The STP voltage should be below 1.5 volts when pedal is released and 7.5-14 volts when pedal is depressed. If STP and ST1- voltage are not as specified, go to next step. If STP and ST1- voltage are as specified, problem is intermittent. Check for defective connections or intermittent problem in wiring harness between stoplight switch and ECM, and for intermittent problem with stoplight switch.
8. Disconnect ECM 35-pin connector E7. (Scheme 58) Check continuity between stop light switch 4-pin connector terminal No. 1 and ECM 35-pin connector E7 terminal No. 19. Then, check continuity between stop light switch 4-pin connector terminal No. 4 and ECM 35-pin connector E7 terminal No. 12. Continuity should exist. Check that continuity does not exist between ground and stop light switch 4-pin connector terminals No. 1 and 4 individually. If continuity is as specified, replace ECM. If continuity is not as specified, repair or replace wires and/or connectors as necessary.

Idle speed is controlled by Electronic Throttle Control System (ETCS). ETCS uses throttle control motor to operate throttle valve opening angle to obtain target idle speed. DTC is set when idle speed continues to vary greatly from target speed. Possible causes are

1. Defective Positive Crankcase Ventilation (PCV) valve hose or connection.
2. Defective ETCS.
3. Air induction system malfunction.

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

1. Using Toyota hand-held tester or scan tool, check for any other DTCs. If only DTC P0505 exists, go to next step. If other DTCs exists, diagnose and repair those DTCs first and then retest.
2. Check for any loose or defective PCV valve hose connections. PCV valve is located on top of passenger's side valve cover near front corner of valve cover. If PCV valve hose connections are okay, go to next step. If PCV valve hose connections are defective, repair or replace components as necessary.
3. Ensure engine oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem does not exist, go to next step. If problem exists, repair as necessary.
4. Check throttle body and components for ECTS. See «THROTTLE BODY»(ref-151979-S41763017912003010900000) under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article.

1. Remove the EFI fuse from the engine room relay box. Check fuse and replace if necessary. (Scheme 95) Measure the voltage between the terminals of the E6 and E8 ECM connectors.
2. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2 Backprobing, measure voltage between ECM 32-pin connector E6 terminal No. 1 (-) and ECM 31-pin connector E8 terminal No. 3 (+) (Blue wire). (Scheme 58) This is the BATT terminal on ECM. The BATT voltage should be 9-14 volts. If BATT voltage is not as specified, go to next step. If BATT voltage is as specified, replace ECM.
3. Disconnect battery terminals. Remove EFI fuse from engine room relay box. Disconnect ECM 31-pin connector E8. Check the harness and connector between the EFI fuse and ECM. Check continuity between the EFI fuse socket terminal No. 2 and ECM 31-pin connector E8 terminal No. 3 (+) (Blue wire). Continuity should exist. Then, check that continuity does not exist between the EFI fuse socket terminal No. 2 and ground. Check continuity between battery positive terminal and EFI fuse socket terminal No. 1. Continuity should exist. Then, check that continuity does not exist between ground and EFI fuse socket terminal No. 1. If continuity is as specified, replace engine room relay box. If continuity is not as specified, repair or replace wire and/or connectors as necessary.

Scheme 95

1. If Toyota hand-held tester is available, go to next step. If Toyota hand-held tester is not available, go to step 6.
2. Check stoplight operation. If stoplights operate properly, go to next step. If stoplights do not operate properly, repair as necessary and retest system. See appropriate EXTERIOR LIGHTS article in ACCESSORIES & EQUIPMENT.
3. Connect hand-held tester to Data Link Connector (DLC3) at driver's side of instrument panel. see scheme 1 Turn ignition on and then turn hand-held tester on.
4. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2 Backprobing, measure voltage between ECM 32-pin connector E6 terminal No. 1 (-) and ECM 35-pin connector E7 terminal No. 12 (+) (Red/Blue wire). This is the ST1- terminal on ECM. Monitor STP signal and ST1- voltage on hand-held tester while depressing and releasing brake pedal. STP signal should indicate ON with brake pedal depressed and OFF with brake pedal released. The ST1- voltage should be below 1.5 volts when pedal is depressed and 7.5-14 volts when pedal is released. If STP signal and ST1- voltage are not as specified, go to next step. If STP signal and ST1- voltage are as specified, problem is intermittent. Check for defective connections or intermittent problem in wiring harness between stoplight switch and ECM, and for intermittent problem with stoplight switch.
5. Disconnect ECM 35-pin connector E7. (Scheme 58) Check continuity between stop light switch 4-pin connector terminal No. 1 and ECM 35-pin connector E7 terminal No. 19. Then, check continuity between stop light switch 4-pin connector terminal No. 4 and ECM 35-pin connector E7 terminal No. 12. Continuity should exist. Check for no continuity between ground and stop light switch 4-pin connector terminal No. 1 and No. 4. If continuity is as specified, replace ECM. If continuity is not as specified, repair or replace wires and/or connectors as necessary.
6. Check stoplight operation. If stoplights operate properly, go to next step. If stoplights do not operate properly, repair as necessary and retest system. See appropriate EXTERIOR LIGHTS article in ACCESSORIES & EQUIPMENT.
7. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2 Backprobing, measure voltage between ECM 32-pin connector E6 terminal No. 1 (-) and ECM 35-pin connector E7 terminal No. 12 (+) (Red/Blue wire). This is the ST1- terminal on ECM. The ST1- voltage should be below 1.5 volts when pedal is depressed and 7.5-14 volts when pedal is released. Then, backprobing, measure voltage between ECM 32-pin connector E6 terminal No. 1 (-) and ECM 35-pin connector E7 terminal No. 19 (+) (Green/Yellow wire). This is the STP terminal on ECM. The STP voltage should be below 1.5 volts when pedal is released and 7.5-14 volts when pedal is depressed. If STP and ST1- voltage are not as specified, go to next step. If STP and ST1- voltage are as specified, problem is intermittent. Check for defective connections or intermittent problem in wiring harness between stoplight switch and ECM, and for intermittent problem with stoplight switch.
8. Disconnect ECM 35-pin connector E7. (Scheme 58) Check continuity between stop light switch 4-pin connector terminal No. 1 and ECM 35-pin connector E7 terminal No. 19. Then, check continuity between stop light switch 4-pin connector terminal No. 4 and ECM 35-pin connector E7 terminal No. 12. Continuity should exist. Check for no continuity between ground and stop light switch 4-pin connector terminal No. 1 and No. 4. If continuity is as specified, replace ECM. If continuity is not as specified, repair or replace wires and/or connectors as necessary.

Replace ECM.

1. Connect Toyota hand-held tester or enhanced OBD II scan tool to Data Link Connector (DLC3) at driver's side of instrument panel. see scheme 1 If Toyota hand-held tester or enhanced OBD II scan tool is not available, go to step 3.
2. Turn ignition on and then turn hand-held tester on. With Toyota hand-held tester or enhanced OBD II scan tool, select the item STARTER SIGNAL in the DATA LIST and read its value displayed on the hand-held tester. With ignition switch ON, STARTER SIGNAL should indicate OFF, and with ignition in START position STARTER SIGNAL should indicate ON. If readings are as specified, check for intermittent problem. System is Ok at this time. Check harness wires, connectors and terminals for damage and repair or replace as necessary. If readings are not as specified, go to step 4.
3. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2 Backprobing, measure voltage between ECM 32-pin connector E6 terminal No. 1 (-) and ECM 34-pin connector E4 terminal No. 17 (+) (Black/Yellow wire) with ignition on and while cranking. (Scheme 58) This is the STA terminal on ECM. The STA voltage should be below 0.5 volts when ignition switch is ON position and 9-14 volts when ignition switch is in START position. If STA voltage is not as specified, go to next step. If STA voltage is as specified, problem is intermittent. Check for defective connections or intermittent problem in wiring harness between park neutral position switch and ECM, and for intermittent problem with park neutral switch.
4. Disconnect the park/neutral position switch 9-pin connector located rear of engine room and on top of transmission. (Scheme 96) Check continuity between each terminal when the shift lever is moved to each range. See «CONTINUITY CHECK - PARK/NEUTRAL POSITION SWITCH»(ref-151976-S25958941452003081400000) for terminal selections. If continuity is as specified, check for cranking holding function circuit. See «CRANKING HOLDING FUNCTION CIRCUIT»(ref-151976-S26150036362003081400000). If continuity is not as specified, replace park/neutral position switch. Then, check for cranking holding function circuit. See «CRANKING HOLDING FUNCTION CIRCUIT»(ref-151976-S26150036362003081400000). CONTINUITY CHECK - PARK/NEUTRAL POSITION SWITCH Shift Range Terminal No. & Between All (Except No.) Specification Condition P 1 (Except 3) 6 (Except 9) No Continuity R 2 (Except 3) No Continuity N 3 (Except 5) 6 (Except 9) No Continuity D, 4 3 (Except 7) No Continuity 3 3 (Except 4) No Continuity 2, L 3 (Except 8) No Continuity

Scheme 96

1. Check resistance of throttle control motor. See «THROTTLE BODY»(ref-151979-S41763017912003010900000) under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If throttle control motor is okay, go to next step. If throttle control motor is defective, replace throttle body with throttle control motor as an assembly. See «THROTTLE BODY»(ref-151984-S20444146202003010900000) under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.
2. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2 Disconnect ECM 32-pin connector E6 and throttle body 6-pin connector. Check continuity between ECM 32-pin connector E6 terminals No. 3 (M+) (Red wire) and throttle body 6-pin connector terminal No. 2. Then, check continuity between ECM 32-pin connector E6 terminals No. 2 (M-) (Green wire) and throttle body 6-pin connector terminal No. 1. (Scheme 58) Ensure no continuity exists between ground and either circuit wires. If continuity is as specified, replace ECM. If continuity is not as specified, repair or replace harness wires and/or connectors as necessary. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article.

1. Remove air inlet hose from throttle body. Visually inspect throttle body for foreign material which may be caught between throttle valve and throttle body. If foreign material exists, remove foreign material and clean throttle body as necessary. If foreign material does not exist, go to next step.
2. Check resistance of throttle control motor. See «THROTTLE BODY»(ref-151979-S41763017912003010900000) under IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If throttle control motor is okay, go to next step. If throttle control motor is defective, replace throttle body with throttle control motor as an assembly. See «THROTTLE BODY»(ref-151984-S20444146202003010900000) under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.
3. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2 Disconnect ECM 32-pin connector E6 and throttle body 6-pin connector. Check continuity between ECM 32-pin connector E6 terminals No. 3 (M+) (Red wire) and throttle body 6-pin connector terminal No. 2. Then, check continuity between ECM 32-pin connector E6 terminals No. 2 (M-) (Green wire) and throttle body 6-pin connector terminal No. 1. (Scheme 58) Ensure no continuity exists between ground and either circuit wires. If continuity is as specified, problem is intermittent. System is Ok at this time. Check harness wires and/or connectors for loose, damaged or corroded terminals and repair or replace as necessary. If continuity is not as specified, repair or replace harness wires and/or connectors as necessary. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article.

1. Remove ETCS fuse (15-amp) from engine room relay box. Inspect ETCS fuse. If ETCS fuse is okay, reinstall fuse and go to next step. If ETCS fuse is defective, replace fuse and check for short in Gray wire between ETCS fuse and ECM 35-pin connector E7 terminal No. 6. (Scheme 58) See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article. ECM is located behind glove box. see scheme 2 Repair wiring as necessary.
2. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2 Using voltmeter, check voltage between body ground and ECM 32-pin connector E6 terminal 1 (-) and ECM 35-pin connector E7 terminal No. 6 (+) (Gray wire). (Scheme 58) This is the E1 and +BM terminal on ECM. If voltage is 9-14 volts, replace ECM. If voltage is not 9-14 volts, go to next step.
3. Disconnect battery terminals. Remove ETCS fuse from engine room relay box. Disconnect ECM 35-pin connector E7. Check the harness and connector between the ETCS fuse and ECM. Check continuity between the ETCS fuse socket terminal No. 2 and ECM 35-pin connector E7 terminal No. 6 (+) (Gray wire). Continuity should exist. Then, check that no continuity exists between the ETCS fuse socket terminal No. 2 and ground. Check continuity between battery positive terminal and ETCS fuse socket terminal No. 1. Continuity should exist. Then, check that continuity does not exist between ground and ETCS fuse socket terminal No. 1. If continuity is as specified, replace engine room relay box. If continuity is not as specified, repair or replace wire and/or connectors as necessary. See appropriate WIRING DIAGRAM under ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article.

Replace ECM. ECM is located behind glove box. see scheme 2 Using Toyota hand-held tester or scan tool, ensure DTCs are cleared from ECM. Turn ignition on and then use hand-held tester or scan tool to check for DTCs. If DTC P2119 exists, replace throttle body. See THROTTLE BODY under FUEL SYSTEMS in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article.

1. If Toyota hand-held tester is available, go to next step. If Toyota hand-held tester is not available, go to step 3.
2. Connect Toyota hand-held tester to Data Link Connector (DLC3) at driver's side of instrument panel. see scheme 1 Turn ignition on and then turn hand-held tester on. Using hand-held tester, monitor accelerator pedal position sensor voltages for VPA1 and VPA2 circuits with accelerator pedal depressed and released. See «ACCELERATOR PEDAL POSITION SENSOR VOLTAGE»(ref-151976-S42849741442003010900000). If voltages are not within specification, go to next step. If voltages are within specification, replace ECM. ECM is located behind glove box. see scheme 2 ACCELERATOR PEDAL POSITION SENSOR VOLTAGE Accelerator Pedal Position & Circuit Identification Volts Accelerator Pedal Depressed VPA1 Circuit 2.6-4.5 VPA2 Circuit 3.4-5.3 Accelerator Pedal Released VPA1 Circuit 0.5-1.1 VPA2 Circuit 1.2-2.0
3. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2 Turn ignition off. Disconnect ECM 31-pin connector E8 and accelerator pedal position sensor 6-pin connector. Check continuity between ground and accelerator pedal position sensor 6-pin connector terminals, individually. Continuity should not exist. Then, check continuity between specified accelerator pedal position sensor 6-pin connector terminals and specified ECM 31-pin connector E8 terminals. See «ECM/APP SENSOR CONTINUITY»(ref-151976-S28690729882003081400000). (Scheme 58) If continuity is as specified, go to next step. If continuity is not as specified, repair or replace wires and/or connectors as necessary. ECM/APP SENSOR CONTINUITY APP Sensor Terminal No. Wire Color ECM 31-Pin Connector E8Terminal No. 6 White/Red 22 5 Light Green/Black 28 4 Black/Yellow 26 3 Red/Black 23 2 Violet/White 29 1 White/Blue 27
4. Reconnect ECM 31-pin connector E8. Turn ignition is on. Using voltmeter, check voltage between ECM 31-pin connector E8 terminal No. 26 (Black/Yellow wire) No. 28 (Light Green/Black wire). (Scheme 58) Also, check voltage between ECM 31-pin connector E8 terminal No. 27 (White/Blue wire) and No. 29 (Violet/White wire). Voltage should be 4.5-5.5 volts on both checks. If voltage readings are not within specification, replace ECM. If voltage readings are within specification, replace accelerator pedal rod assembly located at accelerator pedal.
5. Using hand-held tester or scan tool, clear DTCs. Start engine and test drive, then allow to idle for 15 seconds or more. Check for DTCs P2120, P2122, P2123, P2125, P2127, P2128 and P2138. If DTCs exist, replace ECM. If DTCs do not exist, system is Ok at this time.

1. If Toyota hand-held tester is available, go to next step. If Toyota hand-held tester is not available, go to step 3.
2. Connect Toyota hand-held tester to Data Link Connector (DLC3) at driver's side of instrument panel. see scheme 1 Turn ignition on and then turn hand-held tester on. Using hand-held tester, monitor accelerator pedal position sensor voltages for VPA1 and VPA2 circuits with accelerator pedal depressed and released. See «ACCELERATOR PEDAL POSITION SENSOR VOLTAGE»(ref-151976-S42849741442003010900000). If voltages are not within specification, replace accelerator pedal rod assembly located on accelerator pedal. If voltages are within specification, replace ECM. ECM is located behind glove box. see scheme 2
3. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2 Turn ignition on. Backprobing, measure voltage between specified ECM connector terminals. See «ACCELERATOR PEDAL POSITION SENSOR VOLTAGE»(ref-151976-S29288416102003081400000). If voltage is as specified, replace ECM. If voltage is not as specified, go to next step. ACCELERATOR PEDAL POSITION SENSOR VOLTAGE ECM Connector E8 Terminals No. Volts Accelerator Pedal Depressed (1) 22 (+) - 28 (-) 2.6-4.5 23 (+) - 29 (-) 3.4-5.3 Accelerator Pedal Released (1) 22 (+) - 28 (-) 0.5-1.1 23 (+) - 29 (-) 1.2-2.0 (1) Observe polarity with voltmeter probes.
4. Turn ignition off. Disconnect ECM 31-pin connector E8 and accelerator pedal position sensor 6-pin connector. Check continuity between ground and accelerator pedal position sensor 6-pin connector terminals, individually. Continuity should not exist. Then, check continuity between specified accelerator pedal position sensor 6-pin connector terminals and specified ECM 31-pin connector E8 terminals. See «ECM/APP SENSOR CONTINUITY»(ref-151976-S28690729882003081400000). (Scheme 58) If continuity is as specified, replace accelerator pedal rod assembly located at accelerator pedal. If continuity is not as specified, repair or replace wires and/or connectors as necessary.

The system detects the ignition (IG) switch starting signal (STSW) and the supply current to starter until ECM determines engine starts. The purpose is to reduce the holding time of the ignition key.

1. When turning the ignition switch to the START position, check whether the starter motor operates. If engine starts, system is okay at this time. Check for intermittent problem. Check harness wires, connectors and terminals for damage and repair or replace as necessary. If starter does not operate when key is turned to START position, go to next step.
2. Remove glove box for access to ECM with electrical connectors still installed on ECM. see scheme 2 Backprobing and while cranking, measure voltage between ECM 32-pin connector E6 terminal No. 1 (-) and ECM 34-pin connector E4 terminal No. 17 (+) (Black/Yellow wire). (Scheme 58) This is the STA terminal on ECM. Note the voltage reading. Then, measure voltage between ECM 32-pin connector E6 terminal No. 1 (-) and ECM 35-pin connector E5 terminal No. 9 (+) (Pink wire). This is the STAR terminal on ECM. Note the voltage reading. Then, measure voltage between ECM 32-pin connector E6 terminal No. 1 (-) and ECM 32-pin connector E6 terminal No. 12 (+) (Blue/Yellow wire). This is the STSW terminal on ECM. The specified voltage should be 9-14 volts. If voltage is not as specified, go to list below for direction. If voltage is as specified, go to next step. If voltage between ECM 32-pin connector E6 terminal No. 1 (-) and ECM connector E4 terminal No. 17 (STA) is zero volts, while the other checks are as specified, go to step 6. If voltage between ECM 32-pin connector E6 terminal No. 1 (-) and ECM connector E4 terminal No. 17 (STA) and ECM connector E5 terminal No. 9 (STAR) are both zero volts, while the other check is as specified, replace ECM. If all 3 circuits checked are zero volts, go to step 7.
3. Remove starter relay from engine room relay box. Inspect starter relay. (Scheme 97) If relay checks Ok, go to next step. If relay is bad, replace starter relay.
4. Check the harness and connector between the park/neutral position switch connector and starter relay. Disconnect the park/neutral position switch 9-pin connector. Remove the starter relay from the engine room relay box. Check continuity between park/neutral position switch 9-pin connector terminal No. 6 and starter relay socket terminal No. 1. (Scheme 97) Continuity should exist. Then, ensure no continuity exists between ground and starter relay socket terminal No. 1 and No. 2, individually. If continuity is as specified, go to next step. If continuity is not as specified, repair or replace wire and/or connectors as necessary.
5. Turn ignition on. Measure the voltage between ground and starter relay socket terminal No. 5. If voltage is 9-14 volts, inspect starter assembly and replace if necessary. If voltage is not 9-14 volts, repair or replace wire and/or connectors between starter relay and battery as necessary.
6. Turn ignition off. Check continuity between specified park/neutral position switch terminals with gearshift lever in specified positions. See «PARK/NEUTRAL POSITION SWITCH CONTINUITY»(ref-151976-S39640532542003081400000). (Scheme 96) If continuity is as specified, repair or replace wires and/or connectors between park/neutral position switch and ECM as necessary. If continuity is not as specified, replace park/neutral position switch. PARK/NEUTRAL POSITION SWITCH CONTINUITY Shift Range Terminals No. P 1 & 3, 6 & 9 R 2 & 3 N 3 & 5, 6 & 9 D, 4 3 & 7 3 3 & 4 2, L 3 & 8
7. Check STA No. 2 fuse located in driver's side fuse box. Replace fuse if necessary.
8. Disconnect ignition switch 8-pin connector. Check continuity between the connector terminals (component side). (Scheme 97)for connector terminal selections. If continuity is not as specified, replace ignition switch assembly. If continuity is as specified, repair or replace harness wires and/or connectors between ECM, battery and/or ignition switch as necessary.

Scheme 97