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Engine Controls - Self-Diagnostics: Diagnosis Lexus ES XV30

Testing & Diagnostics 15 illustrations ~13722 words

MALFUNCTION INDICATOR LIGHT (MIL) INSPECTION

Note. The CHECK engine light located on instrument cluster is known as Malfunction Indicator Light (MIL). Inspect MIL to ensure it is operational and will come on if a Diagnostic Trouble Code (DTC) is set.

  1. Turn ignition on with engine off. MIL should come on and remain on. If MIL does not come on, check bulb circuit on instrument cluster and wiring circuit between MIL and ECM. See «WIRING DIAGRAMS»(ref-134952) article.
  2. Start engine and ensure MIL goes off. If MIL remains on with engine running, a malfunction is detected. Proceed to «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-134935-S31116483102002022100000) .

TESTING PROCEDURE

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

  1. Record Customer Complaint Ensure all customer complaints or observations are recorded. Test drive vehicle with customer when necessary for malfunction verification.
  2. Retrieve Diagnostic Trouble Codes & Freeze Frame Data Connect appropriate OBD-II scan tool. Retrieve codes and record any freeze-frame data. See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-134935-S31116483102002022100000) .
  3. Clear Trouble Codes & Freeze Frame Data Clear codes using scan tool. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-134935-S34521729992002022100000) .
  4. Perform Visual Inspection Inspect all connectors of suspect circuit or component. Ensure all connections are clean and tight.
  5. Confirm Symptoms & Trouble Codes Perform road test. Determine if original symptoms are still present. Retrieve codes.
  6. Diagnose & Repair Diagnostic Trouble Codes Perform diagnosis and repair procedures as needed. See «DIAGNOSTIC TESTS»(ref-134935-S04384016952002022100000) . If no codes are present, proceed to «TROUBLE SHOOTING - NO CODES»(ref-134942) article for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.).
  7. Verification Procedure After repairs have been completed, clear all diagnostic trouble codes. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-134935-S34521729992002022100000) . Perform road test. Ensure no codes are present and all symptoms and/or complaints have been repaired.

RETRIEVING DIAGNOSTIC TROUBLE CODES

Note. Diagnostic Trouble Codes (DTCs) may be retrieved using Lexus scan tool or On-Board Diagnostic (OBD-II) scan tool that complies with SAE standard J-1978. Lexus scan tool or OBD-II scan tool may be operated in NORMAL mode when retrieving trouble codes. If no DTCs are retrieved in NORMAL mode, Lexus scan tool may be operated in CHECK mode, or OBD-II J1979-compliant scan tool may be used in CONTINUOUS TEST RESULTS function under MODE 7 to observe current data. For aftermarket scan tool, see owner's manual for instructions.

NORMAL mode is used to retrieve DTCs from Engine Control Module (ECM). CHECK mode (or CONTINUOUS TEST RESULTS function under MODE 7) is used to check for DTCs when operating vehicle to simulate conditions in which DTC was set, and contains a higher sensing ability to detect malfunctions. It is also useful to help determine malfunctions caused by poor electrical connections, which are difficult to determine using NORMAL mode.

Note. If using Lexus scan tool, when ignition is turned from ON to ACC or OFF position, or scan tool is switched from NORMAL mode to CHECK mode, all DTCs and freeze-frame data will be erased. DO NOT switch modes until all DTCs and freeze-frame data are recorded.

CHECK Mode Code Retrieval (Lexus Scan Tool Only)

  1. Ensure vehicle battery is fully charged (at least 11 volts). Apply parking brake. Shift transmission/transaxle into Neutral (M/T) or Park (A/T). Turn A/C and all accessories off. Ensure throttle is in idle position.
  2. Turn ignition off. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 DLC No. 3 connector is located under left side of instrument panel. Turn ignition on with engine off. Turn scan tool on.
  3. Switch scan tool from NORMAL mode to CHECK mode. CHECK mode is operational if MIL on instrument cluster flashes. Start engine. Ensure MIL goes off. Try to simulate conditions of driveability complaint described by customer. NOTE: If ignition is turned from ON to ACC or OFF position, all DTCs and freeze-frame data will be erased. DO NOT switch modes until all DTCs and freeze-frame data are recorded.
  4. Record any DTCs and freeze-frame data displayed for system diagnosis. If driveability problem exists and no codes are present, go to «TROUBLE SHOOTING - NO CODES»(ref-134942) article for diagnosis by symptom.
  5. If any DTCs are present, perform appropriate circuit test. See «DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION»(ref-134935-S06152497012002022100000) table. For more information on freeze-frame data, see «FREEZE-FRAME DATA»(ref-134935-S25196165712002022100000) under INTRODUCTION. For information on 2-trip detection logic codes, see «TWO-TRIP DETECTION LOGIC»(ref-134935-S21353108092002022100000) under INTRODUCTION.
  6. After repairs for DTC have been completed, DTC must be cleared from ECM memory. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-134935-S34521729992002022100000). DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION DTC (1) Description «P0100»(ref-134935-S17314861872002022100000) Mass Airflow (MAF) Sensor Circuit Fault «P0101»(ref-134935-S14797605492002022100000) Mass Airflow (MAF) Sensor Circuit Range/Performance Fault «P0110»(ref-134935-S24128949732002022100000) Intake Air Temperature (IAT) Sensor Circuit «P0115»(ref-134935-S07470685002002022100000) Engine Coolant Temperature (ECT) Sensor Circuit «P0116»(ref-134935-S42177566842002022100000) Engine Coolant Temperature (ECT) Sensor Circuit Range/Performance Fault «P0120»(ref-134935-S41590159922002110800000) Throttle Position (TP)/Pedal Position Sensor Switch "A" Circuit Malfunction «P0121»(ref-134935-S37660374082002110800000) Throttle Position (TP)/Pedal Position Sensor Switch "A" Circuit Range/Performance Fault «P0125»(ref-134935-S08473886272002110800000) Insufficient Coolant Temperature For Closed Loop Fuel Control «P0128»(ref-134935-S03028955982002022100000) Thermostat Malfunction «P0136»(ref-134935-S13685409602002022100000) Heated Oxygen Sensor Circuit Malfunction(Bank 1, Sensor 2) «P0141»(ref-134935-S22555380402002022100000) Heated Oxygen Sensor Heater Circuit (Bank 1, Sensor 2) «P0156»(ref-134935-S13685409602002022100000) Heated Oxygen Sensor Circuit Malfunction (Bank 2, Sensor 2) «P0161»(ref-134935-S22555380402002022100000) Heated Oxygen Sensor Heater Circuit (Bank 2, Sensor 2) «P0171»(ref-134935-S16312628952002110800000) System Too Lean/Rich Bank No. 1 «P0172»(ref-134935-S16312628952002110800000) System Too Lean/Rich Bank No. 1 «P0174»(ref-134935-S16312628952002110800000) System Too Lean/Rich Bank No. 2 «P0175»(ref-134935-S16312628952002110800000) System Too Lean/Rich Bank No. 2 «P0300»(ref-134935-S27585966662002110800000) Random Multiple Cylinder Misfire Detected «P0301-P0306»(ref-134935-S12394432182002022100000) Cylinders No. 1-6 Misfire Detected «P0325»(ref-134935-S26509904102002022100000) Knock Sensor No. 1 Circuit Malfunction «P0330»(ref-134935-S26509904102002022100000) Knock Sensor No. 2 Circuit Malfunction «P0335»(ref-134935-S35607296012002022100000) Crankshaft Position (CKP) Sensor "A" Circuit Malfunction «P0340»(ref-134935-S00649411452002022100000) (2) Variable Valve Timing (VVT) Sensor Circuit «P0420»(ref-134935-S20034955922002022100000) Catalyst System Efficiency Below Threshold (Bank No. 1) «P0430»(ref-134935-S20034955922002022100000) Catalyst System Efficiency Below Threshold (Bank No. 2) «P0440»(ref-134935-S08885033982002022100000) EVAP System Malfunction «P0441»(ref-134935-S38099999342002022100000) Incorrect EVAP Purge Flow «P0442»(ref-134935-S08885033982002022100000) EVAP System Leak Detected (Small Leak) «P0446»(ref-134935-S38099999342002022100000) EVAP Vent Control Fault «P0450»(ref-134935-S24660654492002022100000) EVAP Pressure Sensor Malfunction «P0451»(ref-134935-S24660654492002022100000) EVAP Pressure Sensor Range/Performance Fault «P0500»(ref-134935-S03356675982002111100000) Vehicle Speed Sensor (VSS) Malfunction «P0505»(ref-134935-S38635547762002022100000) Idle Control System Malfunction «P0710»(ref-142323-S12670859872002072900000) (3) Transmission Fluid Temperature Sensor Fault «P0750»(ref-142323-S32175676602002072900000) (3) Shift Solenoid Valve No. 1 Fault «P0753»(ref-142323-S07268582522002072900000) (3) Shift Solenoid Valve No. 1 Electrical Fault «P0755»(ref-142323-S32175676602002072900000) (3) Shift Solenoid Valve No. 2 Fault «P0758»(ref-142323-S07268582522002072900000) (3) Shift Solenoid Valve No. 2 Electrical Fault «P0765»(ref-142323-S32175676602002072900000) (3) Shift Solenoid Valve No. 4 Fault «P0768»(ref-142323-S07268582522002072900000) (3) Shift Solenoid Valve No. 4 Electrical Fault «P0770»(ref-142323-S11169772712002072900000) (3) Lock-Up Solenoid Fault «P0773»(ref-142323-S11169772712002072900000) (3) Lock-Up Solenoid Circuit Electrical Fault «P1130»(ref-134935-S20733710832002022100000) Air/Fuel Sensor Circuit Range/Performance Fault (Bank 1 Sensor 1) «P1133»(ref-134935-S28935212992002022100000) Air/Fuel Sensor Circuit Response Malfunction (Bank 1 Sensor 1) «P1135»(ref-134935-S34004396332002111300000) Air/Fuel Sensor Heater Circuit Malfunction (Bank 1 Sensor 1) «P1150»(ref-134935-S20733710832002022100000) Air/Fuel Sensor Circuit Range/Performance Fault (Bank 2 Sensor 1) «P1153»(ref-134935-S28935212992002022100000) Air/Fuel Sensor Circuit Response Malfunction (Bank 2 Sensor 1) «P1155»(ref-134935-S34004396332002111300000) Air/Fuel Sensor Heater Circuit Malfunction (Bank 2 Sensor 1) «P1300, P1305, P1310, P1315, P1320, P1325»(ref-134935-S36367010262002022100000) Ignitor Circuit Malfunction «P1335»(ref-134935-S02750233392002111300000) Crankshaft Position Sensor Circuit Malfunction (While Engine Running) «P1346»(ref-134935-S12875658122002022100000) (2) Variable Valve Timing (VVT)/Crankshaft Position Sensor Circuit Range/Performance Fault (Bank No. 1) «P1349»(ref-134935-S41540708952002022100000) (2) Variable Valve Timing (VVT) System Malfunction (Bank No. 1) «P1350»(ref-134935-S05447739432002022100000) Variable Valve Timing (VVT)/Camshaft Position Sensor Circuit Fault (Bank No. 2) «P1351»(ref-134935-S12875658122002022100000) (2) Variable Valve Timing (VVT)/Crankshaft Position Sensor Circuit Range/Performance Fault (Bank No. 2) «P1354»(ref-134935-S41540708952002022100000) (2) Variable Valve Timing (VVT) System Malfunction (Bank No. 2) «P1520»(ref-134935-S25257467232002111300000) Stoplight Switch Signal Malfunction «P1600»(ref-134935-S14226928062002022100000) ECM Batt Malfunction «P1633»(ref-134935-S22639330992002111300000) ECM Malfunction «P1656»(ref-134935-S05191829892002022100000) Oil Control Valve (OCV) Malfunction (Bank No. 1) «P1663»(ref-134935-S05191829892002022100000) Oil Control Valve (OCV) Malfunction (Bank No. 2) «P1725»(ref-142323-S03492211912002072900000) (3) Input Turbine Speed Sensor Circuit Fault «P1730»(ref-142323-S42376743372002072900000) (3) Counter Gear Speed Sensor Circuit Fault «P1760»(ref-142323-S41993658982002072900000) (3) Shift Solenoid Valve SLT Fault «P1780»(ref-134935-S21936130342002111300000) Park/Neutral Position Switch Malfunction «B2795»(ref-152104-S00587491362003011400000) (4) Unmatched Key Code «B2796»(ref-152104-S00965411372003011500000) (4) No Communication In Immobilizer System «B2797»(ref-152104-S35255484252003011500000) (4) Communication Malfunction No. 1 «B2798»(ref-152104-S00965411372003011500000) (4) Communication Malfunction No. 2 (1) Some codes are two-trip detection logic code(s). For more information, see «DETECTION LOGIC»(ref-134935-S28293697292002022100000) under INTRODUCTION. (2) May also be referred to as camshaft position sensor. (3) These codes only apply to electronically controlled transmissions. For testing procedures, see appropriate ELECTRONIC CONTROLS article in AUTOMATIC TRANSMISSIONS. (4) MIL will not illuminate. For testing procedures, see ENGINE IMMOBILIZER SYSTEMS - ES300 article in ACCESSORIES & EQUIPMENT.

CONTINUOUS TEST RESULTS Function Under MODE 7

OBD-II J1979-compliant scan tool is required to perform this function. For setup and operating instructions, see scan tool owner's manual.

CLEARING DIAGNOSTIC TROUBLE CODES

  1. After performing repairs, clear ECM memory of all stored Diagnostic Trouble Codes (DTCs) and freeze-frame data. DTCs and freeze-frame data may be cleared by using scan tool and following scan tool manufacturer's instructions. NOTE: If using Lexus Scan Tool, DTCs and freeze-frame data may be cleared by switching from CHECK mode to NORMAL mode or from NORMAL mode to CHECK mode.
  2. DTCs and freeze-frame data may also be cleared by removing EFI fuse from fuse/relay box located in engine compartment. DTCs and freeze-frame data may also be cleared by disconnecting negative battery cable. However, other memory functions (clock, radio, alarm, seats, etc.) will be cancelled and must be reset.

TROUBLE CODE TEST DRIVE CONFIRMATION

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

DLC NO. 3 INSPECTION

  1. If scan tool displays UNABLE TO CONNECT TO VEHICLE when scan tool is connected, try scan tool on another vehicle. If scan tool operates on another vehicle, go to next step. If scan tool does not operate on another vehicle, problem is probably with scan tool.
  2. Check DLC No. 3 for loose or damaged terminals. Ensure DLC No. 3 terminals are in correct position in connector. See «WIRING DIAGRAMS»(ref-134952) article. Repair as necessary. If connector and terminals are okay, go to next step.
  3. Check voltage and resistance between ground and specified terminal on DLC No. 3. See «DLC NO. 3 VOLTAGE & RESISTANCE SPECIFICATIONS»(ref-134935-S23323871502002022100000) table. (Scheme 22) If voltage and resistance readings are not as specified, check wiring circuit. See «WIRING DIAGRAMS»(ref-134952) article.
Terminal No. (Application)Specification
4 (Chassis Ground)One Ohm Or Less
5 (Signal)One Ohm Or Less
7 (BUS+ Line)(1)
16 (Battery Voltage)9-14 Volts
(1) Terminal No. 7 of DLC No. 3 provides a pulse generation during the information transmission from the Engine Control Module (ECM).
(1)Terminal No. 7 of DLC No. 3 provides a pulse generation during the information transmission from the Engine Control Module (ECM).

DLC NO. 3 VOLTAGE & RESISTANCE SPECIFICATIONS

Scheme 22

Scheme 22
Scheme 22

DIAGNOSTIC TESTS

Note. For component locations, see appropriate illustration in THEORY & OPERATION article.

Diagnosis & Repair

  1. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Turn ignition on. Turn on scan tool. Start engine and allow it to idle. Monitor MAF rate. If scan tool reading is 0.0 gm/sec., go to next step. If reading is 160.0 gm/sec. or more once engine is at normal operating temperature, go to step 5.
  2. Disconnect MAF sensor 5-pin connector. Turn ignition on. Using voltmeter, measure voltage between terminals No. 1 (Black/White) and No. 5 (Brown wire) at MAF sensor wiring harness connector. (Scheme 23) If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, see 7.
  3. Access ECM behind glove box. Start engine. Ensure A/C is off. Backprobing ECM connector, measure voltage between ECM connector E9 terminal No. 24 (Red wire) and ECM connector E10 terminal No. 28 (Brown wire). If voltage is.5-3.0 volts, replace ECM and retest system. If voltage is not.5-3.0 volts, go to next step.
  4. Check for short or open circuits in wiring between ECM and MAF sensor. See «WIRING DIAGRAMS»(ref-134952) article. Repair wiring as necessary. If wiring is okay, replace MAF sensor.
  5. Access ECM behind glove box. Turn ignition off. Backprobing, check for open circuit between ECM connector E9 terminal No. 32 (Blue/White wire) and ECM connector E10 terminal No. 28 (Brown wire). If resistance is one ohm or less, go to next step. If resistance is not one ohm or less, replace ECM.
  6. Check for open or short circuit in wiring between ECM and MAF sensor. See «WIRING DIAGRAMS»(ref-134952) article. Repair wiring as necessary. If wiring is okay, replace MAF sensor.
  7. Disconnect negative battery cable. Disconnect ECM E6 and E9 connectors. Check for open circuit between ECM E6 connector terminal No. 1 (Black/Red wire) and terminal No. 3 of computer relay at relay block. Resistance should be one ohm or less. Disconnect ECM E9 connector. Check for open circuit in Blue/White wire between terminal No. 32 (Blue/White wire) and MAF sensor. Resistance should be one ohm or less. If resistances are to specification, check ECM power source circuit. If resistances are not to specification, check and replace harness and connector. See «WIRING DIAGRAMS»(ref-134952) article.

Scheme 23

Scheme 23
Scheme 23

Scheme 24

Scheme 24
Scheme 24

Circuit Description

MAF sensor uses a platinum hot wire maintained at a constant temperature. Airflow past sensor affects temperature and current flow through sensor. If DTC P0101 is set, ECM will operate in fail-safe mode, keeping ignition timing and injection volume constant. DTC P0101 is set when throttle valve is fully closed, MAF sensor output is more than 2.2 volts, and Engine Coolant Temperature (ECT) sensor indicates more than 158°F (70°C) for 10 seconds or more at engine speed of less than 900 RPM.

DTC P0101 will also set when VTA sensor output is .63 volt or more, and MAF sensor output is less than 1.06 volts for 10 seconds or more at engine speed or 1500 RPM or more. Possible cause is faulty MAF sensor.

Diagnostic Aids

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

Retrieve trouble codes. See RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. If only DTC P0101 is displayed, replace MAF sensor and retest system. If other codes are displayed, diagnose and repair those codes first and retest system.

  1. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Turn ignition on. Turn scan tool on. Using scan tool, monitor IAT sensor temperature. If temperature displayed is same as actual intake air temperature, check IAT sensor and ECM connections. Problem is intermittent. If temperature displayed is 284°F (140°C) or more, go to step 4. If temperature displayed is -40°F (-40°C), go to next step.
  2. Turn ignition off. Disconnect MAF sensor 5-pin connector. Connect a fused jumper wire between terminals No. 5 (Brown wire) and No. 4 (Blue/Black wire) at MAF sensor harness connector. Turn ignition on. Using scan tool, monitor IAT sensor temperature. If temperature displayed is 284°F (140°C) or more, ensure MAF connector is okay. If connector is okay, replace MAF sensor and retest system. If temperature displayed is less than 284°F (140°C), go to next step.
  3. Connect jumper wire between ECM E10 terminals No. 20 (Blue/Black wire) and No. 28 (Brown wire). If temperature displayed on scan tool is 284°F (140°C) or more, repair open in Brown or Blue/Black wire between MAF harness connector and ECM connector. If temperature displayed on scan tool is not 284°F (140°C) or more, replace ECM and retest system.
  4. Turn ignition off. Disconnect MAF sensor connector. Turn ignition on. If temperature displayed on scan tool is -40°F (-40°C), replace MAF sensor and retest system. If temperature displayed is not -40°F (-40°C), turn ignition off and go to next step.
  5. Access ECM behind glove box. Disconnect ECM E10 connector. Turn ignition on. If temperature displayed is -40°F (-40°C), locate and repair short circuit in wiring harness between MAF sensor and ECM. (Scheme 24) If temperature displayed by scan tool is not -40°F (-40°C), replace ECM and retest system.
  1. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Turn ignition on. Turn scan tool on. Using scan tool, monitor ECT sensor temperature. If temperature displayed is same as actual coolant temperature, check component and ECM connections. Problem is intermittent. If temperature displayed is 284°F (140°C), go to step 4. If temperature displayed is -40°F (-40°C), go to next step.
  2. Turn ignition off. Disconnect ECT sensor harness connector. Connect a fused jumper wire between terminals No. 2 (Green/Black wire) and No. 1 (Brown wire) at ECT sensor harness connector. Turn ignition on. Using scan tool, monitor ECT sensor temperature. If temperature displayed is 284°F (140°C) or more, ensure ECT connector is okay. If connector is okay, replace ECT sensor and retest system. If temperature displayed is less than 284°F (140°C), go to next step.
  3. Turn ignition off. Remove fused jumper wire. Access ECM behind glove box. Backprobing, connect a fused jumper wire between ECM connector E10 terminals No. 19 (Green/Black wire) and No. 28 (Brown wire). (Scheme 24) If temperature displayed on scan tool is 284°F (140°C) or more, repair open in Brown or Green/Black wire between ECT sensor harness connector and ECM E10 connector. If temperature displayed on scan tool is not 284°F (140°C) or more, replace ECM and retest system.
  4. Turn ignition off. Disconnect ECT sensor harness connector. Turn ignition on. If temperature displayed on scan tool is -40°F (-40°C), replace ECT sensor and retest system. If temperature displayed is not -40°F (-40°C), turn ignition off and go to next step.
  5. Access ECM behind glove box. Disconnect ECM E10 connector. Turn ignition on. If temperature displayed is -40°F (-40°C), locate and repair short circuit in wiring harness between ECT sensor and ECM E10 connector. (Scheme 24) If temperature displayed by scan tool is not -40°F (-40°C), replace ECM and retest system.

The ECT sensor is a thermistor that monitors coolant temperature. If DTC P0116 is set, ECM will operate in a fail-safe mode, in which engine coolant is assumed to be 176°F (80°C). Possible causes are

  1. Faulty ECT sensor.
  2. Faulty cooling system.

Note. If DTCs P0115 and P0116 are output together, diagnose DTC P0115 first. Inspect engine coolant temperature circuit for an open. Repair as necessary. See WIRING DIAGRAMS article.

After confirming DTC P0116, use scan tool to access CURRENT DATA to confirm engine coolant temperature. If temperature displayed on scan tool is -40°F (-40°C), ECT sensor circuit may be open. If temperature displayed on scan tool is 284°F (140°C) or more, ECT sensor circuit may be shorted. Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.

Retrieve trouble codes. See RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. If other codes are displayed, diagnose and repair those codes first and retest system. If only DTC P0116 is displayed, check cooling system thermostat. Replace thermostat as necessary and retest system. If thermostat is okay, replace ECT sensor and retest system.

  1. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Turn ignition on. On scan tool, select THROTTLE POS and THROTTLE POS #2 in DATA LIST and read value displayed. With accelerator pedal released, throttle valve opening position expressed as percentage (VTA1) should be 8-20 percent, with voltage (VTA2) of 2.0-2.0. With throttle depressed, throttle valve opening position expressed as percentage (VTA1) should be 64-96 percent, with voltage (VTA2) of 4.6-5.0. If percentages are not as specified, go to next step. If percentages are as specified, problem may be intermittent. Check component and ECM connections.
  2. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 18 (Yellow wire) and No. 28 (Brown wire) at ECM harness connector E10. (Scheme 24) If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, replace ECM.
  3. Measure voltage between ECM harness connector E10 terminals No. 21 (Light Green wire) and No. 28 (Brown wire). (Scheme 24) With accelerator pedal released, voltage should be.4-1.0 volts. With accelerator pedal depressed, voltage should be 3.2-4.8 volts. Measure voltage between ECM harness connector E10 terminals No. 31 (Black/Red wire) and No. 28 (Brown wire). With accelerator pedal released, voltage should be 2.0-2.9 volts. With accelerator pedal depressed, voltage should be 4.6-5.0 volts. If voltages are to specification, go to next step. If voltages are not to specification, replace ECM.
  4. Disconnect TP sensor 4-pin harness connector. Measure resistance between connector terminals No. 1 and 2. If resistance is 1.2-3.2 k/ohms at 68°F (20°C), go to next step. If resistance is not to specification, replace TP sensor.
  5. Disconnect TP sensor connector and ECM E10 connector. Read throttle opening angle on hand-held tester. With accelerator pedal released, opening percentage should be zero percent. With accelerator pedal depressed, opening percentage should be 64-96 percent. If percentages are not to specification, repair or replace harness and connector. If percentages are to specification, check and replace ECM.

If DTC is displayed, replace TP sensor.

  1. If other DTCs are displayed, diagnose and repair those DTCs first and retest system. If only DTC P0125 is displayed, go to next step.
  2. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Start engine and increase engine speed to 2500 RPM for approximately 90 seconds. Using scan tool, monitor each A/F sensor output voltage. See «AIR/FUEL RATIO SENSOR OUTPUT VOLTAGE SPECIFICATIONS»(ref-134935-S25187982332002021900000) table. If voltage is as specified, go to next step. If voltage is not as specified, go to step 10. AIR/FUEL RATIO SENSOR OUTPUT VOLTAGE SPECIFICATIONS Application & Operating Condition Specification Using OBD-II Scan Tool Engine Idling, Engine Racing & Driving Vehicle (1) (2) Using Toyota Hand-Held Tester Engine Idling, Engine Racing & Driving Vehicle (1) (3) (1) Drive vehicle at 25 MPH or more with engine speed of 1500 RPM or more while opening and closing the throttle. (2) Voltage should not remain at.56 volt or less,.66 volt, or.76 volt or more. (3) Voltage should not remain at 2.80 volts or less, 3.30 volts, or 3.80 volts or more.
  3. Check connection of PCV hose. Repair or replace hose as necessary. If hose is okay, go to next step.
  4. Check harness and connectors between ECM and A/F sensor. See «WIRING DIAGRAMS»(ref-134952) article. Repair harness and connectors as necessary. If harness and connectors are okay, go to next step.
  5. Disconnect suspect A/F sensor harness connector. Measure resistance between terminal B+ (Black wire on bank No. 1; Black/White wire on bank No. 2) and HT (Black/White wire on bank No. 1; Black/Red wire on bank No. 2) at A/F sensor connector (component side). (Scheme 25) Resistance should be 2.16-2.88 ohms at 68°F (20°C). If resistance is not as specified, replace appropriate A/F sensor. If resistance is not as specified, go to next step.
  6. Ensure oil dipstick, oil filler cap and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, go to next step.
  7. Check fuel pressure. See «FUEL SYSTEM»(ref-134934-S01980397212002022100000) in BASIC DIAGNOSTIC PROCEDURES article. If fuel pressure is not to specification, repair as necessary. If fuel pressure is to specification, go to next step.
  8. Check fuel injectors. See «FUEL SYSTEM»(ref-134944-S14140289912002022100000) in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  9. Check exhaust system for leaks. If problem exists, repair as necessary. If problem does not exist, replace defective A/F sensor(s).
  10. Clear DTCs. Perform test drive confirmation, then go to next step. See «TEST DRIVE CONFIRMATION»(ref-134935-S18916324982002110800000) under DTC P1130 OR DTC P1150: AIR/FUEL SENSOR CIRCUIT RANGE/PERFORMANCE.
  11. Recheck for DTCs. If DTC P0125 is displayed again, replace ECM. If DTC P0125 is not displayed again, go to next step.
  12. Vehicle either ran out of fuel or problem is intermittent. Check component and ECM connections.

Scheme 25

Scheme 25
Scheme 25
  1. Remove and inspect cooling system thermostat. If problem exists, replace thermostat as necessary and retest. If problem does not exist, go to next step.
  2. If any other DTCs are displayed, diagnose and repair those DTCs first and retest. If only DTC P0128 is displayed, replace ECM.
  1. If any other DTCs are displayed, diagnose and repair those DTCs first. If only DTCs P0136/P0156 are displayed, go to next step.
  2. Disconnect appropriate oxygen sensor 4-pin connector. Disconnect ECM E9 connector. (Scheme 24) Check continuity between terminals No. 21 (White wire) and No. 29 (Black wire) at ECM E9 connector and appropriate oxygen sensor connector terminal No. 3 (White wire) or No. 3 (Black wire). Resistance should be one ohm or less. Check for short circuit between ECM connector E9 terminals No. 21 (White wire) and No. 29 (Black wire). See «WIRING DIAGRAMS»(ref-134952) article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
  3. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Start and warm engine to normal operating temperature. Read voltage output displayed on hand-held tester when engine is snap accelerated to about 4000 RPM 3 times. Voltage should fluctuate from less than.4 volt to.6 volt or more. If voltage is as specified, problem is intermittent. Check component and ECM connections. If voltage is not as specified, replace oxygen sensor No. 2.
  1. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe between terminal No. 28 at ECM connector E10 and terminals No. 5 (Yellow wire) and No. 6 (Blue wire) at ECM harness connector E8. (Scheme 24) Voltage should be 9-14 volts. If voltage is as specified, replace ECM. If voltage is not as specified, go to next step.
  2. Turn ignition off. Disconnect heated oxygen sensor No. 2 harness connector. Connector is located on front right side of engine. Measure resistance between terminals HT at bank No. 2 (Yellow wire) or bank No. 1 (Blue wire) and B+ (Black/Yellow wire) at heated oxygen sensor connector (component side). Resistance should be 11-16 ohms at 68°F (20°C). If resistance is not as specified, replace heated oxygen sensor No. 2. If resistance is as specified, go to next step.
  3. Disconnect oxygen sensor connector. Disconnect ECM E8 connector. Check for open circuit between terminals HT (Yellow or Blue wire) of oxygen sensor connector and HT1B (Blue wire) and HT2B (Yellow wire) of ECM E8 connector. Resistance should be one ohm or less. Check for short circuit between HT1B (Blue wire) and HT2B (Yellow wire) of ECM E8 connector and E2 (Brown wire) at ECM connector E10. (Scheme 24) Resistance should be one megohm or more. If resistances are to specification, go to next step. If resistances are not to specification, repair or replace harness and connector.
  4. Disconnect negative battery terminal. Disconnect oxygen sensor connector. Check for open circuit between terminal No. 5 of computer relay side connector and +B (Black/White wire) at oxygen sensor connector. Do not insert tester leads hard or holder may be damaged. If resistance is one ohm or less, check ECM power source circuit. If resistance is greater than one ohm, repair or replace harness and connector.

Scheme 26

Scheme 26
Scheme 26
  1. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, go to next step.
  2. Check fuel injectors. See «FUEL SYSTEM»(ref-134944-S14140289912002022100000) in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. Injectors should not leak more than one drop every 12 minutes. If problem exists, repair as necessary. If problem does not exist, go to next step.
  3. Check Mass Airflow (MAF) meter and Engine Coolant Temperature (ECT) sensor. See «ENGINE SENSORS & SWITCHES»(ref-134944-S07748320542002022100000) in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. If problem exists, replace appropriate sensor(s). If problem does not exist, go to next step.
  4. Check spark and ignition system. See «IGNITION CHECKS»(ref-134934-S31811742762002022100000) in BASIC DIAGNOSTIC PROCEDURES article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  5. Check fuel pressure. See «FUEL SYSTEM»(ref-134934-S01980397212002022100000) in BASIC DIAGNOSTIC PROCEDURES article. If fuel pressure is not to specification, repair as necessary. If fuel pressure is as specified, go to next step.
  6. Check exhaust system for leaks. If problem exists, repair as necessary. If problem does not exist, go to next step.
  7. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Start engine and increase engine speed to 2500 RPM for approximately 90 seconds. Using scan tool, monitor each A/F sensor output voltage. See «AIR/FUEL SENSOR OUTPUT VOLTAGE SPECIFICATIONS»(ref-134935-S03492022902002021900000) table. If voltage is not as specified, go to next step. If voltage is as specified, go to step 9. AIR/FUEL SENSOR OUTPUT VOLTAGE SPECIFICATIONS Application & Operating Condition Specification Using OBD-II Scan Tool Engine Idling, Engine Racing & Driving Vehicle (1) (2) Using Toyota Hand-Held Tester Engine Idling, Engine Racing & Driving Vehicle (1) (3) (1) Drive vehicle at 25 MPH or more with engine speed of 1500 RPM or more while opening and closing the throttle. (2) Voltage should not remain at.56 volt or less,.66 volt, or.76 volt or more. (3) Voltage should not remain at 2.80 volts or less, 3.30 volts, or 3.80 volts or more.
  8. Check for open or short in wiring between ECM and A/F sensor. See «WIRING DIAGRAMS»(ref-134952) article. If problem exists, repair wiring as necessary. If problem does not exist, replace appropriate A/F sensor.
  9. Clear DTCs. Perform test drive confirmation, then go to next step. See «TEST DRIVE CONFIRMATION»(ref-134935-S18916324982002110800000) under DTC P1130 OR DTC P1150: AIR/FUEL SENSOR CIRCUIT RANGE/PERFORMANCE.
  10. Recheck for DTCs. If DTCs are displayed again, replace ECM. If no DTCs are displayed again, go to next step.
  11. Vehicle either ran out of fuel or problem is intermittent. Check component and ECM connections.

Test Drive Confirmation

  1. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Record any DTCs and FREEZE FRAME data. Switch scan tool to CHECK mode (Toyota hand-held tester only). Drive vehicle several times with engine speed, load and its surrounding range shown with ENGINE SPD, CALC LOAD in FREEZE FRAME data or MISFIRE RPM and MISFIRE LOAD in scan tool data list.
  2. Drive vehicle at specified engine speeds. See «DRIVING PATTERN»(ref-134935-S21664089762002021900000) table. Turn ignition off after symptom is simulated the first time, then repeat test drive again (OBD-II scan tool only). If a misfire is detected, a DTC will set and misfire will be indicated in FREEZE FRAME data. Turn ignition off and wait a minimum of 5 seconds. DRIVING PATTERN RPM (1) Minutes Idling 3 1/2 1000 3 2000 1 1/2 3000 1 (1) Minimum specification is given.
  1. Check vacuum hoses for leaks, blockage and proper routing. See «VACUUM DIAGRAMS»(ref-134950) article. Also, check wiring and connectors for damage or poor connections. If problem exists, repair as necessary and perform «TEST DRIVE CONFIRMATION»(ref-134935-S18916324982002110800000). If problem does not exist, go to next step.
  2. Check spark and ignition system. See «IGNITION CHECKS»(ref-134934-S31811742762002022100000) in BASIC DIAGNOSTIC PROCEDURES article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  3. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe ECM connector and measure voltage between ground and fuel injector terminals at specified ECM connector. See «IDENTIFYING ECM FUEL INJECTOR TERMINALS»(ref-134935-S32156084902002021900000) table. If voltage is 9-14 volts at each terminal, go to step 6. If voltage is not 9-14 volts at each terminal, go to next step. IDENTIFYING ECM FUEL INJECTOR TERMINALS Fuel Injector No. Terminal No. Wire Color 1 (1) 1 Blue 2 (1) 2 Red 3 (1) 3 Yellow 4 (1) 4 White 5 (1) 5 Red/Blue 6 (1) 6 Green (1) Terminals are located in ECM harness connector E10. (Scheme 24)
  4. Turn ignition off. Disconnect fuel injector harness connector at misfiring cylinder. Measure resistance between fuel injector terminals (component side). Resistance should be 13.4-14.2 ohms at 68°F (20°C). If resistance is as specified, go to next step. If resistance is not as specified, replace appropriate fuel injector.
  5. Check for open or short in wiring between ECM and fuel injector. See «WIRING DIAGRAMS»(ref-134952) article. If problem exists, repair as necessary. If problem does not exist, repair open or short in fuel injector power source circuit. See «WIRING DIAGRAMS»(ref-134952) article.
  6. Check fuel pressure. See «FUEL SYSTEM»(ref-134934-S01980397212002022100000) in BASIC DIAGNOSTIC PROCEDURES. Fuel pressure should be 44-55 psi (3.1-3.9 kg/cm 2 ) at idle, and should be 21 psi (1.5 kg/cm 2 ) or more for 5 minutes after engine has stopped. If fuel pressure is not as specified, repair as necessary. If fuel pressure is as specified, go to next step.
  7. Check fuel injectors. See «FUEL SYSTEM»(ref-134944-S14140289912002022100000) in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. Fuel injector volume should be 3.7-4.5 Cu. In. (60-73 cc) every 15 seconds and difference in volume between each injector should be less than.8 Cu. In. (13 cc). Injectors should not leak more than one drop every 12 minutes. If problem exists, repair as necessary. If problem does not exist, go to next step.
  8. Check EGR system components. See «EMISSION SYSTEMS & SUB-SYSTEMS»(ref-134944-S21434569282002022100000) in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  9. Check Mass Airflow (MAF) meter and Engine Coolant Temperature (ECT) sensor. See «ENGINE SENSORS & SWITCHES»(ref-134944-S07748320542002022100000) in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. If problem exists, replace appropriate sensor(s). If problem does not exist, go to next step.
  10. Check engine compression. See «BASIC DIAGNOSTIC PROCEDURES»(ref-134934) article. Check valve clearance. See «ON-VEHICLE ADJUSTMENTS»(ref-134931) article. Check valve timing. See appropriate article in ENGINES. Repair as necessary.

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

  1. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Disconnect EB1 connector. EB1 connector is an in-line harness connector located on left bank of cylinder head. EB1 connector is a 4-pin, Dark Gray connector. Remove, switch and install terminals No. 1 and 2 from male connector. (Scheme 27) Connect EB1 connector. Turn ignition on. Clear DTCs. Start and warm engine to normal operating temperature. Snap accelerate engine to about 4000 RPM 3 times. Retrieve DTCs. If same DTC is repeated, go to next step. If DTC changed, go to step 3.
  2. Check for open or short in wiring between EB1 connector and ECM. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM. Ensure EB1 male connector terminals are returned to their original position.
  3. Check for open or short in wiring between EB1 connector and knock sensor(s). To access harness, it may be necessary to remove intake manifold. See «KNOCK SENSOR»(ref-134951-S20988864372002022100000) under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION article. If problem exists, repair wiring as necessary. If problem does not exist, replace knock sensor. Ensure EC1 male connector terminals are returned to their original position.

Scheme 27

Scheme 27
Scheme 27
  1. Disconnect CKP sensor harness connector. Measure resistance between CKP sensor connector terminals No. 1 (Green wire) and No. 2 (Red wire). Resistance should be 1630-2740 ohms (cold sensor) or 2065-3225 ohms (hot sensor). If resistance is not as specified, replace CKP sensor. If resistance is as specified, go to next step.
  2. Check for open or short in wiring between ECM and CKP sensor. See «WIRING DIAGRAMS»(ref-134952) article. If problem exists, repair wiring as necessary. If problem does not exist, remove and inspect CKP sensor. Also, inspect signal plate. Replace CKP sensor and/or signal plate as necessary. If both components are okay, replace ECM.
  1. Disconnect VVT sensor harness connector. Using ohmmeter, measure resistance between sensor terminals. Resistance should be 835-1400 ohms at 14-122°F (-10-50°C) or 1060-1645 ohms at 122-212°F (50-100°C). Check resistance at each VVT sensor.
  2. Check the output waveform. (Scheme 28)- (Scheme 30).
  3. Replace sensor(s) as necessary. If sensor(s) is okay, check for open or short circuit in wiring harness between ECM and VVT sensor. See «WIRING DIAGRAMS»(ref-134952) article. Repair as necessary. If wiring harness is okay, remove and inspect sensor(s). Also inspect signal plate. Replace as necessary. If both components are okay, replace ECM and retest system.
  1. If other DTCs are displayed, diagnose and repair those DTCs first and retest system. If only DTC P0420/P0430 are displayed, go to next step.
  2. Check exhaust system for leaks. If problem exists, repair as necessary. If problem does not exist, go to next step.
  3. Check A/F sensor No. 1 and No. 2 circuits. See «DTC P0125: INSUFFICIENT COOLANT TEMPERATURE FOR CLOSED LOOP FUEL CONTROL»(ref-134935-S08473886272002110800000) . If problem exists, repair as necessary. If problem does not exist, go to next step.
  4. Check heated oxygen sensor No. 2 circuits. See «DTC P0136: HEATED OXYGEN SENSOR CIRCUIT (BANK NO. 1, SENSOR NO. 2) & DTC P0156: HEATED OXYGEN SENSOR CIRCUIT MALFUNCTION (BANK NO. 2, SENSOR NO. 2)»(ref-134935-S13685409602002022100000) . If problem exists, repair as necessary. If problem does not exist, replace catalytic converter.
  1. Select ACTIVE TEST mode on hand-held tester. Disconnect vacuum hose from VSV for EVAP. Start engine. Select EVAP VSV (ALONE) in ACTIVE TEST and operate VSV for EVAP. When VSV for EVAP is operated by hand-held tester, apply disconnected hose to your finger to check suction. If VSV is on, disconnected hose should suck. If VSV is off, disconnected hose should not suck. Select item INTAKE CTL VSV1 in ACTIVE TEST and operate VSV for CCV. Check VSV for CCV operation when it is operated by hand-held tester. If VSV is on, disconnected hose should suck. If VSV is off, disconnected hose should not suck. Select item TANK BYPASS VSV in ACTIVE TEST and operate VSV for pressure switching valve. Check VSV for pressure switching valve operation when it is operated by hand-held tester. If VSV is on, disconnected hose should suck. If VSV is off, disconnected hose should not suck. (Scheme 31)- (Scheme 32).
  2. Connect hand-held tester to DLC No. 3. see scheme 1 Select EVAP SYS CHECK mode on hand-held tester. Perform EVAP SYS CHECK. If scan tool detects a leak on fuel tank side, go to next step. If scan tool detects a leak on canister side, go to step 6. If scan tool does not detect a leak in EVAP system, check vacuum hose.
  3. Check if fuel tank cap is properly installed. If problem exists, install fuel tank cap properly and perform EVAP SYS CHECK by hand-held tester. If fuel tank cap is properly installed, go to next step.
  4. Check for damaged fuel tank cap and gasket. If problem exists, replace fuel tank cap with OEM cap. If problem does not exist, go to next step.
  5. Remove fuel tank cap. Visually inspect fuel tank filler neck for damage. If problem exists, replace fuel tank filler neck as necessary. If problem does not exist, check vacuum hoses between vapor pressure sensor and fuel tank, and between charcoal canister and pressure switching valve VSV. Check hoses for correct installation, looseness and damage. If problem exists, repair vacuum hoses as necessary. If problem does not exist, go to next step.
  6. Check hose and tube between fuel tank and charcoal canister for correct installation and damage. If problem exists, repair as necessary. If problem does not exist, go to next step.
  7. Check charcoal canister for damage. If problem exists, repair or replace as necessary. If problem does not exist, go to next step.
  8. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 18 (Yellow wire) and No. 28 (Brown wire) at ECM harness connector E10. (Scheme 24) Voltage should be 4.5-5.5 volts. If voltage is not as specified, replace ECM. If voltage is as specified, go to next step.
  9. Remove fuel tank cap. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between terminal No. 21 (Pink wire) at ECM harness connector E6 and terminal No. 28 (Brown wire) at ECM harness connector E10. (Scheme 24) If voltage is 3.0-3.6 volts, go to step 10. If voltage is not 3.0-3.6 volts, check harness and vapor pressure sensor connector. Repair harness as necessary. If harness is okay, replace vapor pressure sensor assembly.
  10. Check fuel tank and fuel tank overfill valve for damage. If problem exists, repair or replace fuel tank or fuel tank overfill valve as necessary. If problem does not exist, no fault is indicated at this time. Probable cause of DTC to set was an incorrectly installed fuel tank cap.
  1. Check for cracks and deformations in fuel tank, charcoal canister and fuel tank filler pipe. Check for disconnected hoses and tubes around fuel tank and charcoal canister. If problem exists, repair as necessary. If problem does not exist, go to next step.
  2. Check fuel tank cap. If fuel tank cap is not an OEM cap, replace fuel tank cap with an OEM cap. If fuel tank cap is an OEM cap, go to next step.
  3. Check if fuel tank cap is properly installed. If problem exists, install fuel tank cap properly. If fuel tank cap is properly installed, go to next step.
  4. Check for damaged fuel tank cap and gasket. If problem exists, replace fuel tank cap with OEM cap. If problem does not exist, go to next step.
  5. Remove fuel tank cap. Visually inspect fuel tank filler neck for damage. If problem exists, replace fuel tank filler neck as necessary. If problem does not exist, go to next step.
  6. Check vacuum hoses between vapor pressure sensor and fuel tank, and between charcoal canister and pressure switching valve VSV. Check hoses for correct installation, looseness and damage. If problem exists, repair vacuum hoses as necessary. If problem does not exist, go to next step.
  7. Check hose and tube between fuel tank and charcoal canister for correct installation and damage. If problem exists, repair as necessary. If problem does not exist, go to next step.
  8. Check all EVAP system electrical component connections. If problem exists, repair as necessary. If problem does not exist, go to next step.
  9. Check vacuum hoses between charcoal canister and fuel tank, and between fuel filler neck and fuel tank. If problem exists, repair as necessary. If problem does not exist, go to next step.
  10. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 18 (Yellow wire) and No. 28 (Brown wire) at ECM harness connector E10. (Scheme 24) Voltage should be 4.5-5.5 volts. If voltage is not as specified, replace ECM. If voltage is as specified, go to next step.
  11. Remove fuel tank cap. Using DVOM, backprobe ECM harness connector and measure voltage between terminal No. 21 (Pink wire) at ECM harness connector E6 and terminal No. 28 (Brown wire) at ECM harness connector E10. Voltage should be 3.0-3.6 volts. (Scheme 24) If voltage is as specified, go to step 13. If voltage is not as specified, go to next step.
  12. Check for an open or short in wiring between vapor pressure sensor and ECM. See «WIRING DIAGRAMS»(ref-134952) article. If problem exists, repair wiring as necessary. If problem does not exist, replace vapor pressure sensor.
  13. Disconnect EVAP VSV vacuum hoses. Turn ignition on. Access ECM behind glove box. Connect a jumper wire by backprobing between terminal No. 28 (Brown wire) at ECM connector E10 and terminal No. 11 (Light Green wire) at ECM harness connector E8. (Scheme 24) With jumper wire connected air applied to EVAP VSV port "E" should flow from port "F". (Scheme 31) Remove jumper wire. With jumper wire removed, air applied to EVAP VSV port "E" should not flow from port "F". If EVAP VSV functions as specified, go to step 16. If EVAP VSV does not function as specified, go to next step.
  14. Connect all disconnected components. Check EVAP VSV operation. See FUEL EVAPORATIVE SYSTEM under «EMISSION SYSTEMS & SUB-SYSTEMS»(ref-134944-S21434569282002022100000) in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. If EVAP VSV is okay, go to next step. If EVAP VSV is not okay, replace EVAP VSV. Also, clean vacuum hose between throttle body and EVAP VSV, and between EVAP VSV and charcoal canister, then check charcoal canister. See FUEL EVAPORATIVE SYSTEM under «EMISSION SYSTEMS & SUB-SYSTEMS»(ref-134944-S21434569282002022100000) in SYSTEM & COMPONENT TESTING - ES300 & RX300 article.
  15. Check for an open or short in wiring between EFI main relay and EVAP VSV, and between EVAP VSV and ECM. See «WIRING DIAGRAMS»(ref-134952) article. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.
  16. Disconnect canister closed valve VSV vacuum hoses. Turn ignition on. Access ECM behind glove box. Connect a jumper wire by backprobing between terminal No. 28 (Brown wire) at ECM connector E10 and terminal No. 12 (Blue wire) at ECM harness connector E8. (Scheme 24) With jumper wire connected air applied to canister closed valve VSV port "E" should not flow from port "F". see scheme 12 Remove jumper wire. With jumper wire removed, air applied to canister closed valve VSV port "E" should flow from port "F". If canister closed valve VSV does not function as specified, go to next step. If canister closed valve VSV functions as specified, go to step 19.
  17. Connect all disconnected components. Check canister closed valve VSV. See «FUEL EVAPORATION SYSTEM»(ref-134944-S33034179152002022100000) under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. If canister closed valve VSV is okay, go to next step. If canister closed valve VSV is defective, replace canister closed valve VSV and charcoal canister. Also, clean vacuum hose between charcoal canister and canister closed valve VSV.
  18. Check for an open or short in wiring between EFI main relay and canister closed valve VSV, and between canister closed valve VSV and ECM. See «WIRING DIAGRAMS»(ref-134952) article. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.
  19. Disconnect pressure switching valve VSV vacuum hoses. Turn ignition on. Access ECM behind glove box. Connect a jumper wire by backprobing between terminal No. 28 (Brown wire) at ECM connector E10 and terminal No. 4 (Violet wire) at ECM harness connector E6. (Scheme 24) With jumper wire connected air applied to pressure switching valve VSV port "E" should flow from port "F". (Scheme 32) Remove jumper wire. With jumper wire removed, air applied to pressure switching valve VSV port "E" should not flow from port "F". If pressure switching valve VSV functions as specified, go to step 22. If pressure switching valve VSV does not function as specified, go to next step.
  20. Connect all disconnected components. Check pressure switching valve VSV. See «FUEL EVAPORATION SYSTEM»(ref-134944-S33034179152002022100000) under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. If pressure switching valve VSV is defective, replace pressure switching valve VSV and charcoal canister. Also, clean vacuum hose between charcoal canister and pressure switching valve VSV, and between pressure switching valve VSV and fuel tank. If pressure switching valve VSV is okay, go to next step.
  21. Check for an open or short in wiring between EFI main relay and pressure switching valve VSV, and between pressure switching valve VSV and ECM. See «WIRING DIAGRAMS»(ref-134952) article. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.
  22. Connect all disconnected components. Charcoal canister or fuel tank overfill check valve maybe defective. Check fuel evaporative system. See FUEL EVAPORATIVE SYSTEM under «EMISSION SYSTEMS & SUB-SYSTEMS»(ref-134944-S21434569282002022100000) in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. Repair as necessary. If no problem is indicated, replace ECM.

Scheme 28

Scheme 28
Scheme 28

Scheme 29

Scheme 29
Scheme 29

Scheme 30

Scheme 30
Scheme 30
  1. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe and measure voltage between terminals No. 18 (Yellow wire) and No. 28 (Brown wire) at ECM harness connector E10. (Scheme 24) If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, replace ECM.
  2. Using DVOM, backprobe ECM connector and measure voltage between terminals No. 21 (Pink wire) at ECM harness connector E6 and terminal No. 28 (Brown wire) at ECM harness connector E10. (Scheme 24) Disconnect vacuum hose from vapor pressure sensor. Vapor pressure sensor is mounted on charcoal canister. Connect a vacuum pump to vapor pressure sensor. Voltage should be 2.9-3.7 volts without vacuum applied, and less than.5 volt with 1.18 in. Hg applied. If voltage is as specified, replace ECM. If voltage is not as specified, go to next step.
  3. Check for open or short in wiring between vapor pressure sensor and ECM. See «WIRING DIAGRAMS»(ref-134952) article. If problem exists, repair wiring as necessary. If problem does not exist, replace vapor pressure sensor.
  1. Test drive vehicle and check operation of speedometer. If speedometer is not operating correctly, repair speedometer as necessary. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. If speedometer is operating correctly, go to next step.
  2. Raise and support front of vehicle. Shift transmission into Neutral. Access ECM behind glove box. Using DVOM, backprobe ECM E7 connector, terminal No. 17 (Violet/White wire). (Scheme 24) Turn ignition on. Slowly rotate a drive wheel while observing voltage on DVOM. Voltage should fluctuate from zero volts to 4.5-5.5 volts as wheel is turned. If voltage is not as specified, locate and repair open/short circuit between terminal No. 17 (Violet/White wire) at ECM E7 harness connector and instrument cluster C7 connector, terminal No. 33 (White wire). If voltage is as specified, go to next step.
  3. Check for loose or poor connection at ECM E7 connector. Repair as necessary. If connection is okay, replace ECM and retest system.
  1. Check for other DTCs and diagnose those DTCs first. If no other DTCs are present, go to next step.
  2. Check air induction system. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If not problem is present, go to next step.
  3. Inspect throttle body and throttle control motor. See «THROTTLE CONTROLS»(ref-134944-S11423472602002022100000) in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. Check accelerator pedal position sensor. Connect hand-held tester to DLC No. 3. see scheme 1 Check that check engine warning light does not illuminate. When turning accelerator pedal position sensor lever to full-open position, check that throttle valve opening percentage (THROTTLE POS) of CURRENT DATA shows standard value of 60 percent or more. If standard value is not to specification, replace throttle body assembly. If standard valve is to specification, go to next step.
  4. Check throttle body assembly harness and connectors. See «WIRING DIAGRAMS»(ref-134952) article. If harness and connectors are okay, go to next step.
  5. Check throttle position sensor. See «THROTTLE CONTROLS»(ref-134944-S11423472602002022100000) in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. If throttle position sensor is okay, go to next step.
  6. Check throttle position sensor to ECM harness and connectors. See «WIRING DIAGRAMS»(ref-134952) article. Repair as necessary. If harness and connectors are okay, replace ECM.

Diagnosis & Repair (Using Lexus Scan Tool)

  1. Connect Lexus scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Turn ignition on. Turn scan tool on. Using Lexus scan tool, monitor accelerator pedal position sensor voltage at VPA and VPA2 circuits. With throttle fully closed, accelerator pedal position sensor voltage should be.5-1.1 volt at VPA circuit and.9-2.3 volts at VPA2 circuit. Depress accelerator pedal to floor (WOT). With throttle fully open, accelerator pedal position sensor voltage should be 3.0-4.6 volts at VPA circuit and 3.4-5.0 volts at VPA2 circuit. If voltages are as specified, replace ECM and retest. If voltages are not as specified, go to next step.
  2. Access ECM behind glove box. Turn ignition on. Backprobing, measure voltage between ECM E6 connector terminals No. 26 (Red wire) and No. 28 (Light Green/Black wire), and between ECM E6 connector terminals No. 27 (Black/Red wire) and No. 29 (Light Green wire). (Scheme 24) If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, replace ECM and retest.
  3. Turn ignition on. Backprobing, measure voltage between terminals No. 22 (Blue/Yellow wire) and No. 28 (Light Green/Black wire), and terminals No. 23 (White/Red wire) and No. 29 (Light Green wire). (Scheme 24) With fully closed throttle, voltage should be.5-1.1 volt (terminals No. 22 and 28) or.9-2.3 volt (terminals No. 23 and No. 29). With Wide Open Throttle (WOT), voltage should be 3.0-4.6 volts (terminals No. 22 and No. 28) or 3.4-5.0 volt (terminals No. 23 and No. 29. If voltage is not as specified, go to next step. If voltage is as specified, replace ECM and retest.
  4. Check accelerator pedal position sensor operation. See «ENGINE SENSORS & SWITCHES»(ref-134944-S07748320542002022100000) in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. Replace accelerator pedal position sensor as necessary. If accelerator pedal position sensor is okay, check for short or open circuit in wiring harness and sensor connector between ECM E6 connector and accelerator pedal position sensor. See «WIRING DIAGRAMS»(ref-134952) article. Repair wiring as necessary.

Diagnosis & Repair (Using OBD-II Scan Tool)

  1. Access ECM behind glove box. Turn ignition on. Backprobing, measure voltage between ECM E6 connector terminals No. 26 (Red wire) and No. 28 (Light Green/Black wire), and between terminals No. 27 (Black/Red wire) and No. 29 (Light Green wire). (Scheme 24) If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, replace ECM and retest.
  2. Turn ignition on. Backprobing, measure voltage between terminals No. 22 (Blue/Yellow wire) and No. 28 (Light Green/Black wire), and terminals No. 23 (White/Red wire) and No. 29 (Light Green wire). (Scheme 24) With fully closed throttle, voltage should be.5-1.1 volt (terminals No. 22 and 28) or.9-2.3 volt (terminals No. 23 and No. 29). With Wide Open Throttle (WOT), voltage should be 3.0-4.6 volts (terminals No. 22 and No. 28) or 3.4-5.0 volt (terminals No. 23 and No. 29). If voltage is not as specified, go to next step. If voltage is as specified, replace ECM and retest.
  3. Check accelerator pedal position sensor operation. See «ENGINE SENSORS & SWITCHES»(ref-134944-S07748320542002022100000) in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. Replace accelerator pedal position sensor as necessary. If accelerator pedal position sensor is okay, check for short or open circuit in wiring harness and sensor connector between ECM E6 connector and accelerator pedal position sensor. See «WIRING DIAGRAMS»(ref-134952) article. Repair wiring as necessary.

The accelerator pedal position sensor is a 2 variable resistor sensor that monitors throttle opening and accelerator pedal position sensor malfunction. ECM controls throttle motor and electromagnetic clutch based on signal from accelerator pedal position sensor. If DTC P1121 is set, ECM shuts down power to throttle control motor.

DTC P1121 is set when ECM consistently detects difference between VPA and VPA2 circuits out of tolerance. Possible cause is faulty accelerator pedal position sensor.

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

  1. Check accelerator pedal position sensor operation. See «ENGINE SENSORS & SWITCHES»(ref-134944-S07748320542002022100000) in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. If accelerator pedal position sensor is okay, go to next step. If accelerator pedal position sensor is not okay, go to step 3.
  2. Access ECM behind glove box. Turn ignition on. Backprobing, measure voltage between terminals No. 22 (Blue/Yellow wire) and No. 28 (Light Green/Black wire), and terminals No. 23 (White/Red wire) and No. 29 (Light Green wire) at ECM connector E6. (Scheme 24) With fully closed throttle, voltage should be.5-1.1 volt (terminals No. 22 and 28) or.9-2.3 volt (terminals No. 23 and No. 29). With Wide Open Throttle (WOT), voltage should be 3.0-4.6 volts (terminals No. 22 and No. 28) or 3.4-5.0 volt (terminals No. 23 and No. 29). If voltage is not as specified, go to next step. If voltage is as specified, replace ECM and retest.
  3. Disconnect ECM E6 connector. Ensure continuity is present in wiring between ECM and accelerator position sensor. See «WIRING DIAGRAMS»(ref-134952) article. If continuity is not present, repair wiring as necessary. Check continuity (backprobe) between ground and terminals No. 28 (Light Green/Black wire) and No. 29 (Light Green wire). No continuity should be present. Repair wiring as necessary. If wiring is okay, replace accelerator pedal assembly.
  1. Access ECM behind glove box. Start engine. Using oscilloscope, check signal circuits of M+ and M- circuits between ECM and throttle control motor. Backprobe ECM at following terminals: For M+ Circuit Connect oscilloscope between terminal No. 3 of ECM connector E8 (Black wire) and terminal No. 1 of ECM connector E8 (Brown wire). (Scheme 24) For M- Circuit Connect oscilloscope between terminal No. 2 of ECM connector E8 (White wire) and terminal No. 1 of ECM connector E8 (Brown wire). (Scheme 24) Compare to specified oscilloscope patterns. (Scheme 33) Waveform frequency should vary with engine speed. If either circuit does not display specified waveform, go to next step. If both circuits display specified waveform, replace ECM and retest system.
  2. Disconnect throttle control motor 2-pin connector. Measure resistance of motor between connector terminals at throttle control motor connector. Resistance should be.3-100.0 ohms at 68°F (20°C). If resistance is not as specified, replace throttle control motor. If resistance is as specified, go to next step.
  3. Check for open or short circuit in wiring harness or connector between throttle control motor and ECM. See «WIRING DIAGRAMS»(ref-134952) article. Repair wiring as necessary. If wiring and connectors are okay, replace ECM and retest.

Scheme 31

Scheme 31
Scheme 31
  1. Check ETCS fuse (10-amp) from junction block located at left side of engine compartment. If ETCS fuse is okay, go to next step. If ETCS fuse is blown, check for short circuit in wiring harness between ETCS fuse and ECM. See «WIRING DIAGRAMS»(ref-134952) article. Repair wiring as necessary.
  2. Access ECM behind glove box. Backprobing, measure voltage between ECM terminal No. 4 (White/Black wire) at ECM E8 connector and terminal No. 6 (Blue/Red wire) at ECM E7 connector. (Scheme 24) If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, replace ECM.
  3. Check wiring between battery, ETCS fuse, ETCS fuse and ECM. See «WIRING DIAGRAMS»(ref-134952) article. Repair wiring as necessary. If wiring is okay, replace ECM.

Throttle control motor opens and closes throttle valve as commanded by ECM. ECM determines throttle valve position using throttle position sensor. If DTC P1128 is set, ECM shuts down power to throttle control motor.

DTC P1128 is set when throttle control motor locks. Possible causes are

  1. Faulty throttle control motor.
  2. Faulty throttle body.

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

Disconnect throttle control motor 2-pin connector. Measure resistance of motor between connector terminals at throttle control motor connector. Resistance should be .3-100.0 ohms at 68°F (20°C). If resistance is not as specified, replace throttle control motor. If resistance is as specified, remove intake air duct. Visually inspect throttle valve for foreign material. If throttle valve is clean, replace throttle body.

Retrieve trouble codes. See RETRIEVING DIAGNOSTIC TROUBLE CODES under SELF-DIAGNOSTIC SYSTEM. If any other codes are displayed other than DTC P1129, diagnose and repair those codes first. If only DTC P1129 is displayed, check throttle body assembly for binding or other problem. Repair or replace as necessary. If throttle body assembly is okay, replace ECM.

  1. If using OBD-II scan tool, go to step 3. If using Toyota hand-held tester, connect hand-held tester to Data Link Connector (DLC) No. 3. see scheme 1 Switch scan tool to CHECK mode and go to next step.
  2. Start and warm engine to normal operating temperature with all accessories off. Drive vehicle at 38-75 MPH and engine speed at 1600-3200 RPM for 3-5 minutes. Stop vehicle and allow to idle for one minute. If malfunction exists, MIL will illuminate.
  3. Start and warm engine to normal operating temperature. Drive vehicle at 38-75 MPH and engine speed at 1600-3200 RPM for 3-5 minutes. Stop vehicle and allow to idle for one minute. Turn ignition off. Repeat driving and idling part of test. If malfunction exists, MIL will illuminate.
  1. If other DTCs are displayed, diagnose and repair those DTCs first and retest system. If only DTC P1130 and/or P1150 is displayed, go to next step.
  2. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Start engine and increase engine speed to 2500 RPM for approximately 90 seconds. Using scan tool, monitor each A/F sensor output voltage. See «AIR/FUEL RATIO SENSOR OUTPUT VOLTAGE SPECIFICATIONS»(ref-134935-S28520838382002021900000) table. If voltage is as specified, go to next step. If voltage is not as specified, go to step 8. AIR/FUEL RATIO SENSOR OUTPUT VOLTAGE SPECIFICATIONS Application & Operating Condition Specification Using OBD-II Scan Tool Engine Idling, Engine Racing & Driving Vehicle (1) (2) Using Toyota Hand-Held Tester Engine Idling, Engine Racing & Driving Vehicle (1) (3) (1) Drive vehicle at 25 MPH or more with engine speed of 1500 RPM or more while opening and closing the throttle. (2) Voltage should not remain at.56 volt or less,.66 volt, or.76 volt or more. (3) Voltage should not remain at 2.80 volts or less, 3.30 volts, or 3.80 volts or more.
  3. Check for open or short in wiring between ECM and suspect A/F sensor. See «WIRING DIAGRAMS»(ref-134952) article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
  4. Disconnect suspect A/F sensor harness connector. Measure resistance between terminal No. 2 (Black wire on bank No. 1; Black/White wire on bank No. 2) and terminal No. 1 (Black/White wire on bank No. 1; Black/Red wire on bank No. 2) at A/F sensor connector (component side). (Scheme 25) Resistance should be 1.8-3.4 ohms at 68°F (20°C) and 5.0-7.5 ohms at 932°F (500°C). If resistances are not as specified, replace appropriate A/F sensor. If resistances are as specified, go to next step.
  5. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, go to next step.
  6. Check fuel pressure. See «FUEL SYSTEM»(ref-134934-S01980397212002022100000) in «BASIC DIAGNOSTIC PROCEDURES»(ref-134934) article. Fuel pressure should be 44-50 psi (3.1-3.5 kg/cm 2 ) at idle, and should be 21 psi (1.5 kg/cm 2 ) or more for 5 minutes after engine has stopped. If fuel pressure is not as specified, repair as necessary. If fuel pressure is as specified, go to next step.
  7. Check fuel injectors. See «FUEL SYSTEM»(ref-134944-S14140289912002022100000) in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. Fuel injector volume should be 3.7-4.5 Cu. In. (60-73 cc) every 15 seconds and difference in volume between each injector should be less than.8 Cu. In. (13 cc). Injectors should not leak more than one drop every 12 minutes. If problem exists, repair as necessary. If problem does not exist, replace defective A/F sensor.
  8. Clear DTCs. Perform test drive confirmation, then go to next step. See «TEST DRIVE CONFIRMATION»(ref-134935-S18916324982002110800000).
  9. Recheck for DTCs. If DTC P1130 and/or P1150 is displayed again, replace ECM. If neither DTC P1130 nor P1150 is displayed again, go to next step.
  10. Vehicle either ran out of fuel or problem is intermittent. Check component and ECM connections.
  1. If using OBD-II scan tool, go to step 3. If using Toyota hand-held tester, connect hand-held tester to Data Link Connector (DLC) No. 3. see scheme 1 Switch scan tool to CHECK mode and go to next step.
  2. Start and warm engine to normal operating temperature with all accessories off. Drive vehicle at 38-75 MPH with engine speed at 1600-3200 RPM for 3-5 minutes. Stop vehicle and allow to idle for one minute. If malfunction exists, MIL will illuminate.
  3. Start and warm engine to normal operating temperature. Drive vehicle at 38-75 MPH with engine speed at 1600-3200 RPM for 3-5 minutes. Stop vehicle and allow to idle for one minute. Turn ignition off. Repeat driving and idling part of test. If malfunction exists, MIL will illuminate.
  1. If other DTCs are displayed, diagnose and repair those DTCs first and retest system. If only DTC P1133 and/or P1153 is displayed, go to next step.
  2. Connect scan tool to Data Link Connector (DLC) No. 3. see scheme 1 Start engine and increase engine speed to 2500 RPM for approximately 90 seconds. Using scan tool, monitor each A/F sensor output voltage. See «AIR/FUEL SENSOR OUTPUT VOLTAGE SPECIFICATIONS»(ref-134935-S34325389362002021900000) table. If voltage is as specified, go to next step. If voltage is not as specified, go to step 8. AIR/FUEL SENSOR OUTPUT VOLTAGE SPECIFICATIONS Application & Operating Condition Specification Using OBD-II Scan Tool Engine Idling, Engine Racing & Driving Vehicle (1) (2) Using Toyota Hand-Held Tester Engine Idling, Engine Racing & Driving Vehicle (1) (3) (1) Drive vehicle at 25 MPH or more with engine speed of 1500 RPM or more while opening and closing the throttle. (2) Voltage should not remain at.56 volt or less,.66 volt, or.76 volt or more. (3) Voltage should not remain at 2.80 volts or less, 3.30 volts, or 3.80 volts or more.
  3. Check for open or short in wiring between ECM and suspect A/F sensor. See «WIRING DIAGRAMS»(ref-133228) article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
  4. Disconnect suspect A/F sensor harness connector. Measure resistance between terminal No. 2 (Black wire on bank No. 1; Black/White wire on bank No. 2) and terminal No. 1 (Black/White wire on bank No. 1; Black/Red wire on bank No. 2) at A/F sensor connector (component side). (Scheme 25) Resistance should be 1.8-3.4 ohms at 68°F (20°C) and 5.0-7.5 ohms at 932°F (500°C). If resistances are not as specified, replace appropriate A/F sensor. If resistances are as specified, go to next step.
  5. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, go to next step.
  6. Check fuel pressure. See «FUEL SYSTEM»(ref-134934-S01980397212002022100000) in BASIC DIAGNOSTIC PROCEDURES article. Fuel pressure should be 44-50 psi (3.1-3.5 kg/cm 2 ) at idle, and should be 21 psi (1.5 kg/cm 2 ) or more for 5 minutes after engine has stopped. If fuel pressure is not as specified, repair as necessary. If fuel pressure is as specified, go to next step.
  7. Check fuel injectors. See «FUEL SYSTEM»(ref-134944-S14140289912002022100000) in SYSTEM & COMPONENT TESTING - ES300 & RX300 article. Fuel injector volume should be 3.7-4.5 Cu. In. (60-73 cc) every 15 seconds and difference in volume between each injector should be less than.8 Cu. In. (13 cc). Injectors should not leak more than one drop every 12 minutes. If problem exists, repair as necessary. If problem does not exist, replace defective A/F sensor.
  8. Clear DTCs. Perform test drive confirmation, then go to next step. See «TEST DRIVE CONFIRMATION»(ref-134935-S18916324982002110800000).
  9. Recheck for DTCs. If DTC P1133 and/or DTC P1153 is displayed again, replace ECM. If neither DTC P1133 nor P1153 are displayed again, go to next step.
  10. Vehicle either ran out of fuel or problem is intermittent. Check component and ECM connections.

Note. Procedure below is for No. 1 cylinder. If a malfunction is found on other cylinders, check circuit for that particular cylinder.

  1. Check spark plugs. If spark plugs are okay, go to next step. If spark plugs are not okay, replace spark plugs and go to step 4.
  2. Disconnect ignition coil connector. Disconnect ECM E10 connector. Check for open circuit between ECM connector E10 terminal No. 23 (White/Red wire) and White/Red wire at ignition coil connector terminal No. 2. (Scheme 24) Check for short circuit between ECM connector E10 terminal No. 23 (White/Red wire) and terminal No. 28 (Brown wire). (Scheme 24) Repair wiring as necessary. If wiring is okay, go to next step.
  3. Reconnect ECM E10 connector. Disconnect ignition coil connector. Turn ignition on. Measure voltage (backprobe) between ECM E10 connector terminal No. 23 (White/Red wire) and No. 28 (Brown wire). (Scheme 24) If voltage is 4.5-5.5 volts, replace igniter. If voltage is not 4.5-5.5 volts, check for open or short in White/Red wire between terminal No. 25 at ECM harness connector E11 and ignitor. Ignitor is located near left shock tower. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
  4. Disconnect Black, 4-pin ignition coil harness connector. Access ECM behind glove box. Disconnect ECM E10 connector. Using DVOM, backprobe at ECM E10 harness connector terminals No. 8 (Red/White wire) and ignition coil connector. (Scheme 24) Resistance should be one ohm or less. Check for short circuit between ECM connector E10 terminals No. 8 (Red/White wire) and No. 28 (Brown wire). Resistance should be one megohm or less. If resistances are to specification, go to next step. If resistances are not to specification, repair or replace harness and connector.
  5. Access ECM behind glove box. Using DVOM, backprobe between ECM harness connector E10 terminal No. 28 (Brown wire) and terminals No. 8 (Red/White wire), No. 9 (Pink wire), No. 10 (Light Green/Black wire), No. 11 (Blue/Yellow wire), No. 12 (Green/Red wire) and No. 13 (Blue wire) while cranking engine. (Scheme 24) If any readings are not.1-4.5 volts, replace ECM. If all readings are.1-4.5 volts, go to next step.
  6. Disconnect Black 4-pin ignition coil harness connector. Turn ignition on. Measure voltage between terminals No. 1 and 4 at ignition coil connector. If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, check and repair ignitor power source circuit. See «WIRING DIAGRAMS»(ref-134952) article.
  7. Check for open or short in wiring between ignition switch and ignition coils, and between ignition coil and ignitor. If problem exists, repair wiring as necessary. If problem does not exist, replace ignition coil assembly.

Check valve timing. See appropriate article in ENGINES. Repair as necessary. If valve timing is okay, replace ECM.

  1. Check valve timing. See appropriate article in ENGINES. Repair as necessary. If valve timing is okay, go to next step.
  2. Using scan tool, select ACTIVE TEST mode. Note idle speed when OCV is activated by scan tool. If idle speed is normal with OCV off and engine idles rough or stalls when OCV is on, VVT is functioning properly at this time. DTC may have been set because of a foreign object that was temporarily caught in the engine oil system but after a short time system returned to normal. If idle speed does not function as specified, go to next step.
  3. With engine idling, check voltage to OCV. If checking OCV for bank No. 1 (right cylinder head), backprobing, connect oscilloscope between ECM E8 connector terminals No. 13 (Blue/White wire) and No. 14 (Blue/Red wire). (Scheme 24) If checking OCV for bank No. 2 (left cylinder head), backprobing, connect oscilloscope between ECM E8 connector terminals No. 15 (Green/Red wire) and No. 16 (Green/Black wire). (Scheme 24) On all applications, ensure oscilloscope pattern is as shown. (Scheme 35) As engine speed is increased, waveform frequency ("A") should lengthen. If waveform pattern is as shown, go to next step. If waveform pattern is not as shown, replace ECM.
  4. Remove timing belt cover and timing belt. See appropriate article in ENGINES. Remove OCV. Place a shop towel under OCV cylinder head opening. Rotate VVT pulley from left to right about 30 degrees 2-3 times. Oil should drain from OCV cylinder head opening. If oil does not drain from opening, replace VVT pulley/gear assembly and go to next step. If oil drains from opening, go to next step.
  5. With OCV removed, connect a jumper wire between positive battery terminal and terminal No. 1 at OCV. (Scheme 36) Connect another jumper wire between negative battery terminal and terminal No. 2 at OCV and note OCV plunger operation. With battery voltage applied, plunger on end of OCV should extend. Disconnect a jumper wire. Without battery voltage applied, plunger should retract. If OCV operates as specified, go to next step. If OCV does not operate as specified, replace OCV and go to next step.
  6. Check for blockage in OCV. Check oil check valve and oil pipe located under OCV. Repair as necessary. If components are okay, go to next step.
  7. Clear DTCs. Start engine and allow it to idle. Turn ignition off. Turn ignition on and check for DTCs. If DTC P1349 or P1354 is not present, no problem is indicated at this time. DTC may have been set because of a foreign object that was temporarily caught in the engine oil system but after a short time system returned to normal. If DTC P1349 or P1354 is present, replace ECM and retest.

Scheme 32

Scheme 32
Scheme 32

Scheme 33

Scheme 33
Scheme 33
  1. Check valve timing. See appropriate article in ENGINES. Repair as necessary. If valve timing is okay, go to next step.
  2. Start engine and allow it to idle. Disconnect suspect Oil Control Valve (OCV) and note idle speed. Engine idle speed should not change. Using jumper wires, apply battery voltage and ground to OCV. Engine should idle rough or stall. If OCV operates as specified, go to next step. If OCV does not operate as specified, go to step 4.
  3. With engine idling, check voltage to OCV. If checking OCV for bank No. 1 (right cylinder head), backprobing, connect oscilloscope between ECM E8 connector terminals No. 13 (Blue/White wire) and No. 14 (Blue/Red wire). (Scheme 24) If checking OCV for bank No. 2 (left cylinder head), backprobing, connect oscilloscope between ECM E8 connector terminals No. 15 (Green/Red wire) and No. 16 (Green/Black wire). On all applications, ensure oscilloscope waveform pattern is as shown. (Scheme 35) As engine speed is increased, waveform frequency ("A") should lengthen. If waveform pattern is not as shown, replace ECM. If waveform pattern is as shown, no problem is indicated at this time. DTC may have been set because of a foreign object that was temporarily caught in the engine oil system but after a short time system returned to normal.
  4. Remove timing belt cover and timing belt. See appropriate article in ENGINES. Remove OCV. Place a shop towel under OCV cylinder head opening. Rotate VVT pulley from left to right about 30 degrees 2-3 times. Oil should drain from OCV cylinder head opening. If oil does not drain from opening, replace VVT pulley/gear assembly and go to next step. If oil drains from head opening, go to next step.
  5. With OCV removed, connect a jumper wire between positive battery terminal and terminal No. 1 at OCV. (Scheme 36) Connect another jumper wire between negative battery terminal and terminal No. 2 at OCV. With battery voltage applied, plunger on end of OCV should extend. Disconnect jumper wires. Without battery voltage applied, plunger should retract. If OCV operates as specified, go to next step. If OCV does not operate as specified, replace OCV and go to next step.
  6. Check blockage in OCV. Check oil check valve and oil pipe located under OCV. Repair as necessary. If components are okay, go to next step.
  7. Clear DTCs. Start engine and allow it to idle. Turn ignition off. Turn ignition on and check for DTCs. If DTC P1349 or P1354 is not present, no problem is indicated at this time. DTC may have been set because of a foreign object that was temporarily caught in the engine oil system but after a short time system returned to normal. If DTC P1349 or P1354 is present, replace ECM and retest.

Note. Variable Valve Timing (VVT) sensor is also known as camshaft position sensor.

VVT sensor LH consists of a core and a pick up coil. On the signal plate for VVT signal, there are three convex on its outer circumference and it is fixed to the camshaft timing gear. When the camshaft turns, the convex of the signal plate and the air-gap over the pick up coil will switch, and with this the magnetic field will change and generate electricity inside the pick up coil. In addition, VVT sensor LH adopts a sensor using a signal plate and a magnetic resistance element. By switching the air-gap of the signal plate and the sensor, ECM voltage will be converted to a rectangular move and output as a signal. Possible causes are

  1. Open or short in VVT sensor circuit.
  2. Faulty VVT sensor (camshaft position sensor).
  3. Camshaft timing gear.
  4. ECM.

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

  1. Disconnect suspect VVT sensor (camshaft position sensor) connector. Measure resistance between VVT sensor terminals. Resistance should be 835-1400 ohms at 14-122°F (-10-50°C), or 1060-1645 ohms at 122-212°F (50-100°C). Replace VVT sensor as necessary. If resistance is as specified, go to next step.
  2. Check sensor waveform. See step 2 under «DIAGNOSIS & Repair»(ref-134935-S27586064632002111300000) .
  3. Check for open or short circuit in wiring harness between ECM connector and appropriate VVT sensor. See «WIRING DIAGRAMS»(ref-134952) article. Repair as necessary. If wiring harness is okay, inspect VVT sensor installation. Tighten sensor as necessary. If VVT sensor is installed properly, replace ECM and retest.
  1. Check stoplight operation. If stoplights do not operate properly, repair as necessary and retest system. See EXTERIOR LIGHTS article in ACCESSORIES & EQUIPMENT. If stoplights operate properly, go to next step.
  2. Connect hand-held tester to DLC No. 3. see scheme 1 Turn ignition on and push hand-held tester main switch on. Read STP signal on hand-held tester. With brake pedal depressed, STP signal should be on. With brake pedal released, STP signal should be off. If signal is not as specified, go to next step. If signal is as specified, problem is intermittent. Check component and ECM connections.
  3. Check for short in wiring between ECM and stoplight switch. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.
  1. Turn ignition off. Access ECM behind glove box. Using DVOM, backprobe ECM harness connector and measure voltage between ECM connector E10 terminal No. 28 (Brown wire) and connector E7 terminal No. 2 (Black/Yellow wire). (Scheme 24) If voltage is 9-14 volts, replace ECM. If voltage is not 9-14 volts, go to next step.
  2. Remove and inspect EFI fuse (15-amp). EFI fuse is located in engine compartment fuse box. If fuse is blown, check for short to ground in wiring. See «WIRING DIAGRAMS»(ref-134952) article. Repair as necessary and replace fuse. If fuse is okay, check for open in wiring between EFI fuse and ECM. Repair as necessary.

If DTC P1633 is set, replace ECM.

  1. Using scan tool, select ACTIVE TEST mode. Note idle speed when OCV is activated by scan tool. If idle speed is normal with OCV off and engine idles rough or stalls when OCV is on, VVT is functioning properly at this time. Fault is intermittent. DTC may have been set because of a foreign object that was temporarily caught in the engine oil system but after a short time system returned to normal. If idle speed does not function as specified, go to next step.
  2. Start engine and allow it to idle. Disconnect suspect Oil Control Valve (OCV). Using jumper wires, apply battery voltage and ground to OCV. Engine should idle rough or stall. If OCV operates as specified, go to next step. If OCV does not operate as specified, replace OCV.
  3. With engine idling, check voltage to OCV. If checking OCV for bank No. 1 (right cylinder head), backprobing, connect oscilloscope between ECM E8 connector terminals No. 13 (Blue/White wire) and No. 14 (Blue/Red wire). (Scheme 24) If checking OCV for bank No. 2 (left cylinder head), backprobing, connect oscilloscope between ECM E8 connector terminals No. 15 (Green/Red wire) and No. 16 (Green/Black wire). On all applications, ensure oscilloscope pattern is as shown. (Scheme 35) As engine speed is increased, waveform frequency ("A") should lengthen. If waveform pattern is as shown, go to next step. If waveform pattern is not as shown, replace ECM.
  4. Check for an open or short circuit in wiring harness between suspect OCV and ECM. Repair wiring harness as necessary. If wiring harness is okay, fault is intermittent.
  1. Start engine and allow it to idle. Disconnect suspect Oil Control Valve (OCV) and note idle speed. OCV is located in each cylinder head at flywheel side of engine. Engine idle speed should not change. Using jumper wires, apply battery voltage and ground to OCV. Engine should idle rough or stall. If OCV operates as specified, go to next step. If OCV does not operate as specified, replace OCV.
  2. With engine idling, check voltage to OCV. If checking OCV for bank No. 1 (right cylinder head), backprobing, connect oscilloscope between ECM E8 connector terminals No. 13 (Blue/White wire) and No. 14 (Blue/Red wire). (Scheme 24) If checking OCV for bank No. 2 (left cylinder head), backprobing, connect oscilloscope between ECM E8 connector terminals No. 15 (Green/Red wire) and No. 16 (Green/Black wire). On all applications, ensure oscilloscope pattern is as shown. (Scheme 35) As engine speed is increased, waveform frequency ("A") should lengthen. If waveform pattern is as shown, go to next step. If waveform pattern is not as shown, replace ECM.
  3. Check for an open or short circuit in wiring harness between suspect OCV and ECM. Repair wiring harness as necessary. If wiring harness is okay, fault is intermittent.

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

Scheme 34

Scheme 34: Diagnosis & Repair
Scheme 34: Diagnosis & Repair

Scheme 35

Scheme 35
Scheme 35

Scheme 36

Scheme 36
Scheme 36
  1. Warm up engine. Turn ignition off. Connect scan tool to DLC No. 3. see scheme 1 Turn ignition on and push scan tool main switch on. Move shift lever to R, D, 4, 3, 2 and L positions. Select REVERSE, 5TH/DRIVE, 4TH, 3RD, 2ND and LOW in DATALIST and read its value displayed on scan tool. see scheme 18 If diagnosis indicates park/neutral position switch is okay, replace ECM. If diagnosis indicates park/neutral switch is not okay, go to next step.
  2. Disconnect PNP switch harness connector. see scheme 19 Check continuity between appropriate PNP switch terminals (component side) with shift lever in appropriate position. See «PARK/NEUTRAL POSITION SWITCH CONTINUITY»(ref-134935-S11453208462002021900000) table. If problem exists, replace PNP switch. If problem does not exist, go to next step. PARK/NEUTRAL POSITION SWITCH CONTINUITY Shift Lever Position Continuity Between Terminals No. Park 1 & 3; 6 & 9 Reverse 2 & 3 Neutral 3 & 5; 6 & 9 Drive & 4 3 & 7 3 3 & 4 2 & Low 3 & 8
  3. Connect park/neutral position switch connector. Disconnect transmission control switch connector. see scheme 20 Check continuity between each terminal in «SHIFT LOCK CONTROL CONTINUITY»(ref-134935-S25183973252002111300000) table when shift lever is moved to each position. If continuity is present, replace shift lock control unit assembly. If continuity is not present, go to next step. SHIFT LOCK CONTROL CONTINUITY Shift Position Continuity Between Terminals No. P 4-6, 1-3 R 4-6, 1-3 N 4-6, 1-3 D 4-6, 1-3 4 4-6, 1-2 3 4-6, 1-2 2 4-6, 1-3 L 5-6, 1-3
  4. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between ground and specified terminals at ECM harness connector E7 with shift lever in appropriate position. See «PARK/NEUTRAL POSITION SWITCH VOLTAGE»(ref-134935-S38767624072002021900000) table. (Scheme 24) If voltage is as specified, no problem is indicated at this time. If voltage is not as specified, go to next step. PARK/NEUTRAL POSITION SWITCH VOLTAGE Shift Lever Position (1) ECM Terminal No. (Wire Color) Volts Reverse 11 (Red/Black) 10-14 Drive 10 (White/Blue) 10-14 2 9 (Yellow) 10-14 3 20 (Blue/White) 10-14 4 23 (Yellow/Black) 10-14 Low 8 (Blue/Black) 10-14 (1) Measure voltage between ECM connector E8 terminal No. 1 (E1-Brown wire) and appropriate ECM connector E7 terminal.
  5. Check wiring between battery and PNP switch, and between PNP switch and ECM. See «WIRING DIAGRAMS»(ref-134952) article. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.

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