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Engine Control System Self-Diagnostics: Diagnosis Toyota Sienna I

Testing & Diagnostics 14 illustrations ~9569 words

DIAGNOSTIC TROUBLE CODE DEFINITIONS

DTC (1)Description
B2785 (2)Ignition Switch On Malfunction
B2786 (2)Ignition Switch Off Malfunction
B2791 (2)Key Unlock Warning Switch Off Malfunction
B2795 (2)Unmatched Key Code
B2796 (2)No Communication In Immobilizer System
B2797 (2)Communication Malfunction No. 1
B2798 (2)Communication Malfunction No. 2
P0100 (3)Mass Airflow (MAF) Meter Circuit
P0101Mass Airflow (MAF) Meter Circuit Range/Performance
P0110 (3)Intake Air Temperature (IAT) Sensor Circuit
P0115 (3)Engine Coolant Temperature (ECT) Sensor Circuit
P0116Engine Coolant Temperature (ECT) Sensor Circuit Range/Performance
P0120 (3)Throttle Position (TP) Sensor Circuit
P0121Throttle Position (TP) Sensor Circuit Range/Performance
P0125Insufficient Coolant Temperature For Closed Loop Fuel Control (Except Calif. Emissions)
P0125Insufficient Coolant Temperature For Closed Loop Fuel Control (Calif. Emissions)
P0130 (4)Heated Oxygen Sensor No. 1 Circuit (Except Calif. Emissions)
P0133 (4)Heated Oxygen Sensor No. 1 Circuit Slow Response (Except Calif. Emissions)
P0135 (3) (4)Heated Oxygen Sensor No. 1 Heater Circuit (Except Calif. Emissions)
P0136 (5)Heated Oxygen Sensor No. 2 Circuit
P0141 (3) (5)Heated Oxygen Sensor No. 2 Heater Circuit
P0150 (6)Heated Oxygen Sensor No. 1 Circuit (Except Calif. Emissions)
P0153 (6)Heated Oxygen Sensor No. 1 Circuit Slow Response (Except Calif. Emissions)
P0155 (3) (6)Heated Oxygen Sensor No. 1 Heater Circuit (Except Calif. Emissions)
P0171System Too Lean (Except Calif. Emissions)
P0171System Too Lean (Calif. Emissions)
P0172System Too Rich (Except Calif. Emissions)
P0172System Too Rich (Calif. Emissions)
P0300Random Misfire Detected
P0301Cylinder No. 1 Misfire Detected
P0302Cylinder No. 2 Misfire Detected
P0303Cylinder No. 3 Misfire Detected
P0304Cylinder No. 4 Misfire Detected
P0305Cylinder No. 5 Misfire Detected
P0306Cylinder No. 6 Misfire Detected
P0325 (3)Knock Sensor No. 1 Circuit
P0330 (3)Knock Sensor No. 2 Circuit
P0335Crankshaft Position (CKP) Sensor Circuit
P0340Camshaft Position (CMP) Sensor Circuit
P0420Catalyst System Efficiency Below Threshold (Except Calif. Emissions)
P0420Catalyst System Efficiency Below Threshold (Calif. Emissions)
P0440Evaporative Emission Control System
P0441Incorrect EVAP Purge Flow
P0446EVAP Vent Control Circuit
P0450EVAP Pressure Sensor Circuit
P0451EVAP Pressure Sensor Range/Performance
P0500Vehicle Speed Sensor Circuit
P0505Idle Air Control (IAC) System Circuit
P0710 (7)Transmission Fluid Temperature Sensor Malfunction
P0750 (7)Shift Solenoid Valve No. 1 Malfunction
P0753 (7)Shift Solenoid Valve No. 1 Electrical Malfunction
P0755 (7)Shift Solenoid Valve No. 2 Malfunction
P0758 (7)Shift Solenoid Valve No. 2 Electrical Malfunction
P0770 (7)Lock-Up Solenoid Malfunction
P0773 (7)Lock-Up Solenoid Circuit Electrical Malfunction
P1130 (4)Air/Fuel Sensor Circuit Range/Performance (Calif. Emissions)
P1133 (4)Air/Fuel Sensor Circuit Response (Calif. Emissions)
P1135 (4)Air/Fuel Sensor Heater Circuit (Calif. Emissions)
P1150 (6)Air/Fuel Sensor Circuit Range/Performance (Calif. Emissions)
P1153 (6)Air/Fuel Sensor Circuit Response (Calif. Emissions)
P1155 (6)Air/Fuel Sensor Heater Circuit (Calif. Emissions)
P1300 (3)Ignitor Circuit
P1335 (8)Crankshaft Position (CKP) Sensor Circuit
P1520Stoplight Switch Signal Circuit (A/T)
P1600ECM BATT Circuit
P1780Park/Neutral Position (PNP) Switch Circuit (A/T)
(1) Some codes are two-trip detection logic code(s). For more information, see TWO-TRIP DETECTION LOGIC in SELF-DIAGNOSTICS - INTRODUCTION article. (2) These codes are for models equipped with engine immobilizer system. MIL will not illuminate. For testing procedures, see appropriate ENGINE IMMOBILIZER SYSTEMS article in ACCESSORIES & EQUIPMENT. (3) If this code is set, ECM will enter fail-safe mode. (4) This code applies to bank No. 1, sensor No. 1. (5) This code applies to bank No. 1, sensor No. 2. (6) This code applies to bank No. 2, sensor No. 1. (7) These codes only apply to models with electronically controlled transmissions. For testing procedures, see appropriate ELECTRONIC CONTROLS article in AUTOMATIC TRANSMISSIONS. (8) MIL will not illuminate.
(1)Some codes are two-trip detection logic code(s). For more information, see TWO-TRIP DETECTION LOGIC in SELF-DIAGNOSTICS - INTRODUCTION article.
(2)These codes are for models equipped with engine immobilizer system. MIL will not illuminate. For testing procedures, see appropriate ENGINE IMMOBILIZER SYSTEMS article in ACCESSORIES & EQUIPMENT.
(3)If this code is set, ECM will enter fail-safe mode.
(4)This code applies to bank No. 1, sensor No. 1.
(5)This code applies to bank No. 1, sensor No. 2.
(6)This code applies to bank No. 2, sensor No. 1.
(7)These codes only apply to models with electronically controlled transmissions. For testing procedures, see appropriate ELECTRONIC CONTROLS article in AUTOMATIC TRANSMISSIONS.
(8)MIL will not illuminate.

DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION

DIAGNOSTIC TESTS

Note. Before performing any diagnostic test, see SELF-DIAGNOSTICS - INTRODUCTION article for diagnostic system functions and system diagnostic procedures. For component location, see appropriate illustration in THEORY & OPERATION article. References to California emissions apply to vehicles with California emissions, which may be verified by underhood Emission Control label. Vehicles with California emissions may be available in other states.

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

Note. To identify ECM terminals referenced in testing, see illustration. (Scheme 1)

Scheme 1

Scheme 1: DIAGNOSTIC TESTS
Scheme 1: DIAGNOSTIC TESTS

Diagnosis & Repair

  1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 2) Start and warm engine to normal operating temperature. Using scan tool, monitor MAF meter flow rate. If scan tool reading is 0.0 gm/sec., go to next step. If scan tool reading is 271 gm/sec. or more, go to step 5.
  2. Turn ignition off. Disconnect MAF meter harness connector. Turn ignition on. Measure voltage between ground and terminal No. 4 (Black/Yellow wire) at MAF meter harness connector. (Scheme 3) If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, repair open in Black/Yellow wire between EFI main relay and MAF meter. See WIRING DIAGRAMS article.
  3. Turn ignition off. Connect MAF meter harness connector. Access ECM behind glove box. Ensure shift lever is in Neutral or Park. Ensure A/C switch is off. Start engine and let idle. Using DVOM, backprobe ECM harness connector and measure voltage between ground and terminal No. 10 (Pink wire) at ECM harness connector E11. (Scheme 1) If voltage is not 1.1-1.5 volts, go to next step. If voltage is 1.1-1.5 volts, replace ECM.
  4. Check for open or short in Pink wire between MAF meter and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace MAF meter.
  5. Turn ignition off. Access ECM behind glove box. Using DVOM, backprobe ECM harness connector and measure resistance between ground and terminal No. 19 (Red/Black wire) at ECM harness connector E11. (Scheme 1) If resistance is one ohms or less, go to next step. If resistance is greater than one ohm, replace ECM.
  6. Check for open in Red/Black wire between MAF meter and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace MAF meter.

Scheme 2

Scheme 2
Scheme 2

Scheme 3

Scheme 3
Scheme 3

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

  1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 2) Turn ignition on. Using scan tool, monitor IAT sensor temperature. If temperature displayed on scan tool is same as outside temperature, problem is intermittent. Check component and ECM connections. If temperature displayed on scan tool is -40°F (-40°C), go to next step. If temperature displayed on scan tool is 284°F (140°C) or more, go to step 4.
  2. Turn ignition off. Disconnect MAF meter harness connector. Using a jumper wire, connect MAF meter harness connector terminals No. 1 (Blue/Yellow wire) and No. 2 (Brown wire). (Scheme 3) Turn ignition on. Using scan tool, monitor IAT sensor temperature. If temperature displayed on scan tool is 284°F (140°C) or more, replace MAF meter. If temperature displayed on scan tool is less than 284°F (140°C), go to next step.
  3. Turn ignition off. Remove jumper wire. Access ECM behind glove box. Using a jumper wire, backprobe between terminals No. 18 (Brown wire) and No. 22 (Blue/Yellow wire) at ECM harness connector E11. (Scheme 1) If temperature displayed on scan tool is 284°F (140°C) or more, repair open in Blue/Yellow wire and/or Brown wire between MAF meter and ECM. See WIRING DIAGRAMS article. If temperature displayed on scan tool is less than 284°F (140°C), replace ECM.
  4. Turn ignition off. Disconnect MAF meter harness connector. Turn ignition on. If temperature displayed on scan tool is -40°F (-40°C), replace MAF meter. If temperature displayed on scan tool is not -40°F (-40°C), go to next step.
  5. Turn ignition off. Access ECM behind glove box. Disconnect ECM harness connector E11. (Scheme 1) Turn ignition on. If temperature displayed on scan tool is -40°F (-40°C), repair short in Blue/Yellow wire between MAF meter and ECM. See WIRING DIAGRAMS article. If temperature displayed on scan tool is not -40°F (-40°C), replace ECM.
  1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 2) Turn ignition on. Using scan tool, monitor ECT sensor temperature. If temperature displayed on scan tool is same as actual coolant temperature, problem is intermittent. Check component and ECM connections. If temperature displayed on scan tool is -40°F (-40°C), go to next step. If temperature displayed on scan tool is 284°F (140°C) or more, go to step 4.
  2. Turn ignition off. Disconnect ECT sensor harness connector (2-pin harness connector with Green/Black wire and Brown wire). Using a jumper wire, connect ECT sensor harness connector terminals. Turn ignition on. Using scan tool, monitor ECT sensor temperature. If temperature displayed on scan tool is less than 284°F (140°C), go to next step. If temperature displayed on scan tool is 284°F (140°C) or more, replace ECT sensor.
  3. Turn ignition off. Remove jumper wire. Access ECM behind glove box. Using a jumper wire, backprobe between terminals No. 18 (Brown wire) and No. 14 (Green/Black wire) at ECM harness connector E11. (Scheme 1) If temperature displayed on scan tool is 284°F (140°C) or more, repair open in Green/Black wire and/or Brown wire between ECT sensor and ECM. See WIRING DIAGRAMS article. If temperature displayed on scan tool is less than 284°F (140°C), replace ECM.
  4. Turn ignition off. Disconnect ECT sensor harness connector. Turn ignition on. If temperature displayed on scan tool is -40°F (-40°C), replace ECT sensor. If temperature displayed on scan tool is not -40°F (-40°C), go to next step.
  5. Turn ignition off. Access ECM behind glove box. Disconnect ECM harness connector E11. (Scheme 1) Turn ignition on. If temperature displayed on scan tool is -40°F (-40°C), repair short in Green/Black wire between ECT sensor and ECM. See WIRING DIAGRAMS article. If temperature displayed on scan tool is not -40°F (-40°C), replace ECM.
  1. If any other DTCs are displayed, diagnose and repair those DTCs first and retest. If only DTC P0116 is displayed, go to next step.
  2. Remove and inspect cooling system thermostat. If problem exists, replace thermostat as necessary and retest. If problem does not exist, replace ECT sensor.
  1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 2) Turn ignition on. Using scan tool, monitor throttle valve opening percentage. Opening percentage should be approximately 10 percent with fully closed throttle and 75 percent with fully open throttle (WOT). If percentages are not as specified, go to next step. If percentages are as specified, problem may be intermittent. Check component and ECM connections.
  2. Turn ignition off. Disconnect TP sensor harness connector. Turn ignition on. Measure voltage between ground and terminal No. 1 (Yellow wire) at TP sensor harness connector. If voltage is 4.5-5.5 volts, go to next step. If voltage is not 4.5-5.5 volts, go to step 5.
  3. Turn ignition off. Check TP sensor. See ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - V6 & V8 article. If sensor is defective, replace TP sensor. If sensor is okay, go to next step.
  4. Connect TP sensor harness connector. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 23 (Blue/White wire) and No. 18 (Brown wire) at ECM harness connector E11. (Scheme 1) Voltage should be.3-1.0 volt with throttle fully closed and 2.7-5.2 volts with throttle fully open (WOT). If voltages are as specified, replace ECM. If voltages are not as specified, repair open or short in Blue/White wire between TP sensor and ECM. See WIRING DIAGRAMS article.
  5. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 2 (Yellow wire) and No. 18 (Brown wire) at ECM harness connector E11. (Scheme 1) If voltage is 4.5-5.5 volts, repair open in Yellow wire between TP sensor and ECM. See WIRING DIAGRAMS article. If voltage is not 4.5-5.5 volts, replace ECM.

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

  1. If any other DTCs are displayed, diagnose and repair those DTCs first and retest. If only DTC P0125 is displayed, go to next step.
  2. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 2) Start and warm engine to normal operating temperature. Using scan tool, monitor each heated oxygen sensor No. 1. Snap accelerate engine to about 4000 RPM 3 times. Both heated oxygen sensors No. 1 should indicate a rich signal (.45 volt or more) at least once. If a rich signal is indicated for both heated oxygen sensors No. 1 at least once, go to step 9. If either heated oxygen sensor No. 1 does not display a rich signal at least once, go to next step.
  3. Check for open or short in wiring between appropriate heated oxygen sensor(s) No. 1 and ECM. If problem does not exist, go to next step. If problem exists, repair wiring as necessary. See WIRING DIAGRAMS article.
  4. Using scan tool, check if a misfire has occurred by monitoring DTCs and DATA LIST. If a misfire has occurred, perform «DTC P1300: IGNITOR CIRCUIT»(ref-2630-S19280715612000041000000). If misfire has not occurred, go to next step.
  5. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, go to next step.
  6. Check fuel pressure. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If fuel pressure is not within specification, repair as necessary. If fuel pressure is within specification, go to next step.
  7. Check fuel injectors. See FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  8. Check exhaust system for leaks. If problem exists, repair as necessary. If problem does not exist, replace defective heated oxygen sensor(s) No. 1.
  9. Perform test drive confirmation, then go to next step. See «TEST DRIVE CONFIRMATION»(ref-2630-S27691934252000041000000) under DTC P0130 OR P0150: HEATED OXYGEN SENSOR NO. 1 CIRCUIT (EXCEPT CALIF. EMISSIONS).
  10. Clear and recheck for DTCs. If DTC P0125 is displayed again, replace ECM. If DTC P0125 is not displayed again, go to next step.
  11. Vehicle either ran out of fuel or problem is intermittent. Check component and ECM connections.
  1. If other DTCs are displayed, diagnose and repair those DTCs first and retest system. If only DTC P0125 is displayed, go to next step.
  2. Connect scan tool to Data Link Connector (DLC) No. 3. Start engine and increase engine speed to 2500 RPM for approximately 90 seconds. Using scan tool, monitor each A/F sensor output voltage. See «AIR/FUEL RATIO SENSOR VOLTAGE SPECIFICATIONS»(ref-2630-S41483066002000041000000) table. If voltage is as specified, go to next step. If voltage is not as specified, go to step 9. AIR/FUEL RATIO SENSOR VOLTAGE SPECIFICATIONS Application (1) Volts Using OBD-II Scan Tool Engine Idling 0.66 Engine Racing 0.76 Or More Driving Vehicle (2) 0.56 Or Less Using Toyota Hand-Held Tester Engine Idling 3.3 Engine Racing 3.8 Or More Driving Vehicle (2) 2.8 Or Less (1) Voltage should not remain constant at specification given. (2) Drive vehicle at 25 MPH or more, with engine speed at 1500 RPM or more, while opening and closing throttle valve.
  3. Check for open or short in wiring between ECM and suspect A/F sensor. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
  4. Disconnect suspect A/F sensor harness connector. Measure resistance between terminal B+ (Black wire) and HT (Blue wire) at A/F sensor connector (component side). (Scheme 4) Resistance should be.8-1.4 ohms at 68°F (20°C) and 1.8-3.2 ohms at 1472°F (800°C). If resistances are not as specified, replace appropriate A/F sensor. If resistances are as specified, go to next step.
  5. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, go to next step.
  6. Check fuel pressure. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If fuel pressure is not within specification, repair as necessary. If fuel pressure is within specification, go to next step.
  7. Check fuel injectors. See FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  8. Check exhaust system for leaks. If problem exists, repair as necessary. If problem does not exist, replace defective A/F sensor.
  9. Perform test drive confirmation, then go to next step. See «TEST DRIVE CONFIRMATION»(ref-2630-S27691934252000041000000) under DTC P1130 OR P1150: AIR/FUEL SENSOR CIRCUIT RANGE/PERFORMANCE (CALIF. EMISSIONS).
  10. Clear and recheck for DTCs. If DTC P0125 is displayed again, replace ECM. If DTC P0125 is not displayed again, go to next step.
  11. Vehicle either ran out of fuel or problem is intermittent. Check component and ECM connections.

Scheme 4

Scheme 4
Scheme 4

Test Drive Confirmation

Note. If conditions in test drive confirmation procedure are not strictly followed, detection of malfunction will not be possible.

  1. If using OBD-II scan tool, go to step 3. If using Toyota hand-held tester, connect hand-held tester to Data Link Connector (DLC) No. 3. (Scheme 2) Switch tester to CHECK mode and go to next step.
  2. Start and warm engine to normal operating temperature with all accessories off. Drive vehicle at 31-40 MPH for 1-3 minutes. Stop vehicle and allow to idle for one minute. Repeat driving and idle part of test 3 times. If malfunction exists, MIL will illuminate.
  3. Start and warm engine to normal operating temperature. Drive vehicle at 31-40 MPH for 1-3 minutes. Stop vehicle and allow to idle for one minute. Turn ignition off. Repeat driving and idle part of test. If malfunction exists, MIL will illuminate.
  1. If other DTCs are displayed, diagnose and repair those DTCs first and retest system. If only DTC P0130 and/or P0150 are displayed, go to next step.
  2. Connect scan tool to Data Link Connector (DLC) No. 3. Start engine and increase engine speed to 2500 RPM for approximately 90 seconds. Let engine idle. Using scan tool, monitor each heated oxygen senor No. 1 output voltage. Voltage should alternate repeatedly between less than .4 volt and more than .55 volt. If voltage is as specified, go to step 7 . If voltage is not as specified, go to next step.
  3. Check for open or short in wiring between ECM and heated oxygen sensors No. 1. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
  4. 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.
  5. Check fuel pressure. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If fuel pressure is not within specification, repair as necessary. If fuel pressure is within specification, go to next step.
  6. Check fuel injectors. See FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, repair as necessary. If problem does not exist, replace appropriate heated oxygen sensor No. 1.
  7. Perform test drive confirmation, then go to next step. See «TEST DRIVE CONFIRMATION»(ref-2630-S27691934252000041000000) .
  8. Clear and recheck for DTCs. If DTC P0130 and/or P0150 are displayed again, replace ECM. If neither DTC P0130 or P0150 are displayed again, problem is intermittent. Check component and ECM connections.
  1. If other DTCs are displayed, diagnose and repair those DTCs first and retest system. If only DTC P0133 and/or P0153 are displayed, go to next step.
  2. Connect scan tool to Data Link Connector (DLC) No. 3. Start engine and increase engine speed to 2500 RPM for approximately 90 seconds. Let engine idle. Using scan tool, monitor each heated oxygen sensor No. 1 output voltage. Voltage should alternates repeatedly between less than .4 volt and more than .55 volt. If voltage is as specified, go to step 7 . If voltage is not as specified, go to next step.
  3. Check for open or short in wiring between ECM and heated oxygen sensors No. 1. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
  4. 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.
  5. Check fuel pressure. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If fuel pressure is not within specification, repair as necessary. If fuel pressure is within specification, go to next step.
  6. Check fuel injectors. See FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, repair as necessary. If problem does not exist, replace appropriate heated oxygen sensor No. 1.
  7. Perform test drive confirmation, then go to next step. See «TEST DRIVE CONFIRMATION»(ref-2630-S27691934252000041000000) under DTC P0130 OR P0150: HEATED OXYGEN SENSOR NO. 1 CIRCUIT (EXCEPT CALIF. EMISSIONS).
  8. Clear and recheck for DTCs. If DTC P0133 and/or P0153 are displayed again, replace ECM. If neither DTC P0133 nor P0153 are displayed again, problem is intermittent. Check component and ECM connections.
  1. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe ECM harness connector. If DTC P0135 is set, measure voltage between ground and terminal No. 3 (Blue/Black wire) at ECM harness connector E11. If DTC P0155 is set, measure voltage between ground and terminal No. 4 (Yellow/Red wire) at ECM harness connector E11. (Scheme 1) Voltage should be 9-14 volts at each terminal. If voltage is as specified, replace ECM. If voltage is not as specified, go to next step.
  2. Disconnect suspect heated oxygen sensor No. 1 harness connector. Measure resistance between terminals B+ (Black/Yellow wire) and HT (Blue/Black wire on bank No. 1; Yellow/Red wire on bank No. 2) at heated oxygen sensor connector (component side). (Scheme 5) Resistance should be 11-16 ohms at 68°F (20°C). If resistance is not as specified, replace appropriate heated oxygen sensor. If resistance is as specified, go to next step.
  3. Repair wiring between ECM and appropriate heated oxygen sensor, or between appropriate heated oxygen sensor and EFI main relay. See WIRING DIAGRAMS article.

Scheme 5

Scheme 5
Scheme 5
  1. If any other DTCs are displayed, diagnose and repair those DTCs first. If only DTC P0136 is displayed, go to next step.
  2. Check for open or short in wiring between ECM and heated oxygen sensor No. 2. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
  3. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 2) Start and warm engine to normal operating temperature. Monitor heated oxygen sensor No. 2 output voltage. Snap accelerate engine to about 4000 RPM 3 times. Voltage should fluctuate from less than.4 volt to.5 volt or more (.6 volt or more on all except California emissions). If voltage is as specified, problem is intermittent. Check component and ECM connections. If voltage is not as specified, replace heated oxygen sensor No. 2.
  1. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe between ground and terminal No. 9 (Pink/Blue wire) at ECM harness connector E9. (Scheme 1) Voltage should be 9-14 volts. If voltage is as specified, replace ECM. If voltage is not as specified, go to next step.
  2. Turn ignition off. Disconnect heated oxygen sensor No. 2 harness connector. Connector is located underneath carpet on passenger's side, near center console. It may be necessary to remove passenger's seat to access connector. Measure resistance between terminals HT (Pink/Blue wire) and B+ (Black/Red wire) at heated oxygen sensor No. 2 connector (component side). (Scheme 6) 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. Repair wiring between ECM and heated oxygen sensor No. 2, or between heated oxygen sensor No. 2 and EFI main relay. See WIRING DIAGRAMS article.

Scheme 6

Scheme 6
Scheme 6
  1. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, go to next step.
  2. Check fuel injectors. See FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  3. Check Mass Airflow (MAF) meter and Engine Coolant Temperature (ECT) sensor. See ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, replace appropriate component. If problem does not exist, go to next step.
  4. Check spark and ignition system. See IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  5. Check fuel pressure. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If fuel pressure is not within specification, repair as necessary. If fuel pressure is within specification, go to next step.
  6. Check exhaust system for leaks. If problem exists, repair as necessary. If problem does not exist, go to next step.
  7. Connect scan tool to Data Link Connector (DLC) No. 3. Start engine and increase engine speed to 2500 RPM for approximately 90 seconds. Let engine idle. Using scan tool, monitor each heated oxygen sensors No. 1 output voltage. Voltage should alternate repeatedly between less than .4 volt to more than .55 volt. If voltage is as specified, go to step 9 . If voltage is not as specified, go to next step.
  8. Check for open or short in wiring between ECM and heated oxygen sensor No. 1. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace appropriate heated oxygen sensor(s) No. 1.
  9. Perform test drive confirmation, then go to next step. See «TEST DRIVE CONFIRMATION»(ref-2630-S27691934252000041000000) under DTC P0130 OR P0150: HEATED OXYGEN SENSOR NO. 1 CIRCUIT (EXCEPT CALIF. EMISSIONS).
  10. Clear and recheck for DTCs. If DTCs P0171 and/or P0172 are displayed again, replace ECM. If neither DTC P0171 and P0172 are displayed again, go to next step.
  11. Vehicle either ran out of fuel, or problem is intermittent. Check component and ECM connections.
  1. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, go to next step.
  2. Check fuel injectors. See FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  3. Check Mass Airflow (MAF) meter and Engine Coolant Temperature (ECT) sensor. See ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, replace appropriate component. If problem does not exist, go to next step.
  4. Check spark and ignition system. See IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  5. Check fuel pressure. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If fuel pressure is not within specification, repair as necessary. If fuel pressure is within specification, go to next step.
  6. Check exhaust system for leaks. If problem exists, repair as necessary. If problem does not exist, go to next step.
  7. Connect scan tool to Data Link Connector (DLC) No. 3. Start engine and increase engine speed to 2500 RPM for approximately 90 seconds. Using scan tool, monitor each A/F sensor output voltage. See «AIR/FUEL RATIO SENSOR VOLTAGE SPECIFICATIONS»(ref-2630-S34411517442000041000000) table. If voltage is not as specified, go to next step. If voltage is as specified, go to step 9 . AIR/FUEL RATIO SENSOR VOLTAGE SPECIFICATIONS Application (1) Volts Using OBD-II Scan Tool Engine Idling 0.66 Engine Racing 0.76 Or More Driving Vehicle (2) 0.56 Or Less Using Toyota Hand-Held Tester Engine Idling 3.3 Engine Racing 3.8 Or More Driving Vehicle (2) 2.8 Or Less (1) Voltage should not remain constant at specification given. (2) Drive vehicle at 25 MPH or more, with engine speed at 1500 RPM or more, while opening and closing throttle valve.
  8. Check for open or short in wiring between ECM and A/F sensor. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace appropriate A/F sensor.
  9. Perform test drive confirmation, then go to next step. See «TEST DRIVE CONFIRMATION»(ref-2630-S27691934252000041000000) under DTC P1130 OR P1150: AIR/FUEL SENSOR CIRCUIT RANGE/PERFORMANCE (CALIF. EMISSIONS).
  10. Clear and recheck for DTCs. If DTCs P0171 and/or P0172 are displayed again, replace ECM. If neither DTC P0171 nor P0172 are displayed again, go to next step.
  11. Vehicle either ran out of fuel or problem is intermittent. Check component and ECM connections.
  1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 2) Record any DTCs and freeze frame data. Switch scan tool to CHECK mode (Toyota hand-held tester only). Drive vehicle several times with engine speed, load and its surrounding range shown with ENGINE SPD, CALC LOAD in freeze frame data or MISFIRE RPM and MISFIRE LOAD in scan tool data list.
  2. Drive vehicle at specified engine speeds. See «DRIVING PATTERN»(ref-2630-S33083048482000041000000) 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. Also, check wiring and connectors for damage or poor connections. If problem exists, repair as necessary and perform «TEST DRIVE CONFIRMATION»(ref-2630-S24000723472000041000000). If problem does not exist, go to next step.
  2. Check spark and ignition system. See IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  3. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between ground and fuel injector terminals at specified ECM connector. See «IDENTIFYING FUEL INJECTOR TERMINALS»(ref-2630-S17179769532000041000000) table. (Scheme 1) If voltage is 9-14 volts at each terminal, go to step 6. If voltage is not 9-14 volts at each terminal, go to next step. IDENTIFYING FUEL INJECTOR TERMINALS Fuel Injector No. Terminal No. Wire Color 1 (1) 5 Blue/Red 2 (1) 6 Red 3 (2) 1 Yellow 4 (2) 2 White 5 (2) 3 Red/Blue 6 (2) 4 Green (1) Terminal are located in ECM harness connector E11. (Scheme 1) (2) Terminals are located in ECM harness connector E12. (Scheme 1)
  4. Disconnect fuel injector harness connector at misfiring cylinder. Measure resistance between fuel injector terminals (component side). Resistance should be 13.4-14.2 ohms at 68°F (20°C). If resistance is as specified, go to next step. If resistance is not as specified, replace fuel injector.
  5. Check for open or short in wiring between ECM and fuel injector. See WIRING DIAGRAMS article. If problem exists, repair as necessary. If problem does not exist, repair open or short in injector power source circuit. See WIRING DIAGRAMS article.
  6. Check fuel pressure. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If fuel pressure is not within specification, repair as necessary. If fuel pressure is within specification, go to next step.
  7. Check fuel injectors. See FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, repair as necessary. If problem does not exist, go to next step.
  8. Check Mass Airflow (MAF) meter and Engine Coolant Temperature (ECT) sensor. See ENGINE SENSORS & SWITCHES in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, replace appropriate component. If problem does not exist, go to next step.
  9. Check engine compression. See BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If engine compression is okay, check valve clearance. See ON-VEHICLE ADJUSTMENTS - V6 & V8 article. If valve clearance is okay, it may be necessary to check valve timing. See appropriate article in ENGINES.

Circuit Description

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

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

Diagnostic Aids

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

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

  1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 2) Disconnect EA1 connector. EA1 connector is an in-line harness connector located under throttle body. EA1 connector is a 4-pin, Dark Gray connector. Remove, switch and install terminals No. 1 and 2 from male connector. (Scheme 7) Connect EA1 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 EA1 connector and ECM. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM. Ensure EA1 male connector terminals are returned to their original position.
  3. Check for open or short in wiring between EA1 connector and knock sensor(s). To access harness, it may be necessary to remove intake manifold. See KNOCK SENSOR under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article. If problem exists, repair wiring as necessary. If problem does not exist, replace appropriate knock sensor. Ensure EA1 male connector terminals are returned to their original position.

Scheme 7

Scheme 7
Scheme 7
  1. Disconnect CKP sensor harness connector. Measure resistance between CKP sensor connector terminals (component side). Resistance should be 1630-2740 ohms (cold sensor) or 2065-3225 ohms (hot sensor). If resistance is not as specified, replace CKP sensor. If resistance is as specified, go to next step.
  2. Check for open or short in wiring between ECM and CKP sensor. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, remove and inspect CKP sensor. Also inspect signal plate. Replace CKP sensor and/or signal plate as necessary. If both components are okay, replace ECM.
  1. Disconnect CMP sensor harness connector. Measure resistance between CMP sensor connector terminals (component side). Resistance should be within specification. See «CAMSHAFT POSITION SENSOR RESISTANCE»(ref-2630-S40282677152000041000000) table. If resistance is as specified, go to next step. If resistance is not as specified, replace CMP sensor. CAMSHAFT POSITION SENSOR RESISTANCE Application Ohms ND Type Sensor Cold 835-1400 Hot 1060-1645 Wabash Type Sensor Cold 1690-2560 Hot 2145-3010
  2. Check for open or short in wiring between ECM and CMP sensor. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
  3. Remove and inspect CMP sensor. Also inspect signal plate. If problem exists, replace CMP sensor and/or signal plate as necessary. If problem does not exist, replace ECM.
  1. If other DTCs are displayed, diagnose and repair those DTCs first and retest system. If only DTC P0420 is displayed, go to next step.
  2. Check exhaust system for leaks. If problem exists, repair as necessary. If problem does not exist, go to next step.
  3. Check heated oxygen sensors No. 1 circuits. See «DTC P0130 OR P0150: HEATED OXYGEN SENSOR NO. 1 CIRCUIT (EXCEPT CALIF. EMISSIONS)»(ref-2630-S32281524712000041000000) . If problem exists, repair as necessary. If problem does not exist, go to next step.
  4. Check heated oxygen sensor No. 2 circuits. See «DTC P0136: HEATED OXYGEN SENSOR NO. 2 CIRCUIT»(ref-2630-S27600648052000041000000) . If problem exists, repair as necessary. If problem does not exist, replace catalytic converter.
  1. If other DTCs are displayed, diagnose and repair those DTCs first and retest system. If only DTC P0420 is displayed, go to next step.
  2. Check exhaust system for leaks. If problem exists, repair as necessary. If problem does not exist, go to next step.
  3. Check A/F sensor circuits. See «DTC P0125: INSUFFICIENT COOLANT TEMPERATURE FOR CLOSED LOOP FUEL CONTROL (CALIF. EMISSIONS)»(ref-2630-S05060810982000041000000) . If problem exists, repair as necessary. If problem does not exist, go to next step.
  4. Check heated oxygen sensor No. 2 circuits. See «DTC P0136: HEATED OXYGEN SENSOR NO. 2 CIRCUIT»(ref-2630-S27600648052000041000000) . If problem exists, repair as necessary. If problem does not exist, replace catalytic converter.

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

  1. Check for cracks, deformations in fuel tank, charcoal canister and fuel tank filler pipe. Check for disconnected hose and tubes around fuel tank and charcoal canister. If problem exists, repair as necessary. If problem does not exist, go to next step.
  2. Check fuel cap. If fuel cap is not an OEM cap, replace cap with an OEM cap. If fuel cap is an OEM cap, go to next step.
  3. Check if fuel cap is properly installed. If problem exists, install fuel cap properly. If fuel cap is properly installed, go to next step.
  4. Check for damaged fuel cap and gasket. If problem exists, replace fuel cap with OEM cap. If problem does not exist, go to next step.
  5. Remove fuel cap. Visually inspect fuel tank filler neck for damage. If problem exists, replace fuel tank filler neck as necessary. If problem does not exist, go to next step.
  6. Check vacuum hoses between vapor pressure sensor and vapor pressure sensor VSV, and between vapor pressure sensor VSV and charcoal canister. 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. Visually inspect charcoal canister for cracks, holes and damage. If problem exists, replace charcoal canister as necessary. If problem does not exist, go to next step.
  9. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 2 (Yellow wire) and No. 18 (Brown wire) at ECM harness connector E11. (Scheme 1) If voltage is not 4.5-5.5 volts, replace ECM. If voltage is 4.5-5.5 volts, go to next step.
  10. Using DVOM, backprobe ECM harness connector and measure voltage between terminal No. 17 (Blue/Red wire) at ECM harness connector E8 and terminal No. 18 (Brown wire) at ECM harness connector E11. Disconnect vacuum hose from vapor pressure sensor. Connect a vacuum pump to vapor pressure sensor. Voltage should be 2.9-3.7 volts without vacuum applied and.5 volt or less with 1.18 in. Hg applied. If voltage is as specified, go to step 12. If voltage is not as specified, go to next step.
  11. Check for an open or short in wiring between vapor pressure sensor and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace vapor pressure sensor.
  12. Connect all previously disconnected components and hoses. Disconnect vacuum hose from charcoal canister port "A" (vacuum hose from fuel tank-to-charcoal canister). (Scheme 8) Ensure fuel cap is installed properly. Apply approximately.71 psi (.05 kg/cm 2 ) pressure to disconnected vacuum hose. If fuel tank does not hold pressure for a minimum of one minute, replace fuel tank as necessary. If fuel tank holds pressure, no fault is indicated at this time. Probable cause of DTC to set was an incorrectly installed fuel cap.

Scheme 8

Scheme 8
Scheme 8
  1. Check EVAP VSV, vapor pressure sensor VSV and vapor pressure sensor connectors for damaged pins, corrosion and loose wires. For component locations, see appropriate illustration in THEORY & OPERATION article. If problem exists, repair connectors as necessary. If problem does not exist, go to next step.
  2. Check all EVAP related vacuum hoses for cracks, looseness and correct routing. For proper vacuum hose routing, see appropriate illustration in VACUUM DIAGRAMS article. If problem exists, repair vacuum hoses as necessary. If problem does not exist, go to next step.
  3. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 2 (Yellow wire) and No. 18 (Brown wire) at ECM harness connector E11. (Scheme 1) If voltage is not 4.5-5.5 volts, replace ECM. If voltage is 4.5-5.5 volts, go to next step.
  4. Using DVOM, backprobe ECM harness connector and measure voltage between terminal No. 17 (Blue/Red wire) at ECM harness connector E8 and terminal No. 18 (Brown wire) at ECM harness connector E11. (Scheme 1) Disconnect vacuum hose from vapor pressure sensor. Connect a vacuum pump to vapor pressure sensor. Voltage should be 2.9-3.7 volts without vacuum applied and.5 volt or less volts with 1.18 in. Hg applied. If voltage is as specified, go to step 6. If voltage is not as specified, go to next step.
  5. Check for open or short in wiring between vapor pressure sensor and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace vapor pressure sensor.
  6. Disconnect EVAP VSV vacuum hoses. Apply air pressure to EVAP VSV port "E". (Scheme 9) Air should not flow from port "F". Access ECM behind glove box. Turn ignition on. Using a jumper wire, backprobe between ground and terminal No. 7 (Light Green wire) at ECM harness connector E11. (Scheme 1) Air should flow from port "F". If EVAP VSV operates as specified, go to step 10. If EVAP VSV does not operate as specified, go to next step.
  7. Check vacuum hose between intake manifold and EVAP VSV, and hose between EVAP VSV and charcoal canister. If problem exists, replace vacuum hoses as necessary. If problem does not exist, go to next step.
  8. Check EVAP VSV. See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, replace EVAP VSV. If problem does not exist, go to next step.
  9. Check for open or short in wiring between EFI main relay and EVAP VSV, and between EVAP VSV and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.
  10. Disconnect vapor pressure sensor VSV vacuum hoses. Apply air pressure to vapor pressure sensor VSV port "E". (Scheme 10) Air should flow from port "G". Access ECM behind glove box. Turn ignition on. Using a jumper wire, backprobe between ground and terminal No. 9 (White/Red wire) at ECM harness connector E8. (Scheme 1) Air should flow from port "F". If vapor pressure sensor VSV does not operate as specified, go to next step. If vapor pressure sensor VSV operates as specified, check charcoal canister. Perform appropriate fuel EVAP system test. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article.
  11. Check vapor pressure sensor VSV. See EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, replace vapor pressure sensor VSV. If problem does not exist, go to next step.
  12. Check for open or short in wiring between EFI main relay and vapor pressure sensor VSV, and between vapor pressure sensor VSV and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring harness as necessary. If problem does not exist, replace ECM.

Scheme 9

Scheme 9
Scheme 9

Scheme 10

Scheme 10
Scheme 10
  1. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 2 (Yellow wire) and No. 18 (Brown wire) at ECM harness connector E11. (Scheme 1) If voltage is not 4.5-5.5 volts, replace ECM. If voltage is 4.5-5.5 volts, go to next step.
  2. Using DVOM, backprobe ECM harness connector and measure voltage between terminal No. 17 (Blue/Red wire) at ECM harness connector E8 and terminal No. 18 (Brown wire) at ECM harness connector E11. (Scheme 1) Disconnect vacuum hose from vapor pressure sensor. Connect a vacuum pump to vapor pressure sensor. Voltage should be 2.9-3.7 volts without vacuum applied and.5 volt or less with 1.18 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 article. If problem exists, repair wiring as necessary. If problem does not exist, replace vapor pressure sensor.
  1. Test drive vehicle and check operation of speedometer. If speedometer is not operating correctly, repair speedometer as necessary. See appropriate INSTRUMENT PANELS article in ACCESSORIES & EQUIPMENT. If speedometer is operating correctly, go to next step.
  2. Access ECM behind glove box. Ensure ignition is off. Disconnect ECM harness connector E9. Check continuity between ground and terminal No. 22 (Violet/Yellow wire) at ECM harness connector E9. (Scheme 1) If continuity exists, locate and repair short to ground. If continuity does not exist, go to next step.
  3. Turn ignition on. Measure voltage between ground and terminal No. 22 (Violet/Yellow wire) at ECM harness connector E12. If voltage is 9-14 volts, replace ECM. If voltage is not 9-14 volts, repair open in wiring between instrument cluster and ECM. See WIRING DIAGRAMS article.
  1. Start engine and warm to normal operating temperature. Turn all accessories off. Ensure A/C is off. Shift transaxle lever into Neutral. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 2) Note engine RPM. Using a jumper wire, connect terminals TE1 and E1 at DLC No. 1 in engine compartment. (Scheme 11) Note engine RPM and compare RPM readings. If difference in engine speed is more than 100 RPM, go to step 6. If difference in engine speed is 100 RPM or less, go to next step.
  2. Turn ignition off. Access ECM behind glove box. Disconnect ECM harness connector E12. (Scheme 1) Turn ignition on. Measure voltage between ground and terminals No. 15 (Yellow/Black wire) and No. 16 (Red/White wire) at ECM harness connector E12. If both readings are 9-14 volts, go to step 4. If either reading is not 9-14 volts, go to next step.
  3. Turn ignition off. Disconnect IAC valve harness connector. Measure resistance between terminal No. 2 and terminals No. 1 and 3 at IAC valve (component side). (Scheme 12) If resistance is not 17-25 ohms (cold) or 22-29 ohms (hot), replace IAC valve. If resistance is 17-25 ohms (cold) or 22-29 ohms (hot), repair open or short in wiring between IAC valve and ECM. See WIRING DIAGRAMS article.
  4. Check IAC valve operation. See IDLE CONTROL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, replace IAC valve. If problem does not exist, go to next step.
  5. Remove IAC valve from throttle body. Check IAC valve and passages for carbon build-up and blockage. If problem exists, repair or replace as necessary. If problem does not exist, replace ECM.
  6. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, an open or short in A/C switch signal circuit may exist. Check A/C amplifier. See appropriate article in AIR CONDITIONING & HEATING. Repair as necessary.

Scheme 11

Scheme 11
Scheme 11

Scheme 12

Scheme 12
Scheme 12
  1. If using OBD-II scan tool, go to step 3. If using Toyota hand-held tester, connect hand-held tester to Data Link Connector (DLC) No. 3. (Scheme 2) Switch scan tool to CHECK mode and go to next step.
  2. Start and warm engine to normal operating temperature with all accessories off. Drive vehicle at 38-75 MPH and engine speed at 1600-3200 RPM for 3-5 minutes. Stop vehicle and allow to idle for one minute. If malfunction exists, MIL will illuminate.
  3. Start and warm engine to normal operating temperature. Drive vehicle at 38-75 MPH and engine speed at 1600-3200 RPM for 3-5 minutes. Stop vehicle and allow to idle for one minute. Turn ignition off. Repeat driving and idle part of test. If malfunction exists, MIL will illuminate.
  1. If other DTCs are displayed, diagnose and repair those DTCs first and retest system. If only DTC P1130 and/or P1150 is displayed, go to next step.
  2. Connect scan tool to Data Link Connector (DLC) No. 3. Start engine and increase engine speed to 2500 RPM for approximately 90 seconds. Using scan tool, monitor each A/F sensor output voltage. See «AIR/FUEL RATIO SENSOR VOLTAGE SPECIFICATIONS»(ref-2630-S36836917402000041000000) table. If voltage is as specified, go to next step. If voltage is not as specified, go to step 8. AIR/FUEL RATIO SENSOR VOLTAGE SPECIFICATIONS Application (1) Volts Using OBD-II Scan Tool Engine Idling 0.66 Engine Racing 0.76 Or More Driving Vehicle (2) 0.56 Or Less Using Toyota Hand-Held Tester Engine Idling 3.3 Engine Racing 3.8 Or More Driving Vehicle (2) 2.8 Or Less (1) Voltage should not remain constant at specification given. (2) Drive vehicle at 25 MPH or more, with engine speed at 1500 RPM or more, while opening and closing throttle valve.
  3. Check for open or short in wiring between ECM and suspect A/F sensor. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
  4. Disconnect suspect A/F sensor harness connector. Measure resistance between terminal B+ (Black wire) and HT (Blue wire) at A/F sensor connector (component side). (Scheme 4) Resistance should be.8-1.4 ohms at 68°F (20°C) and 1.8-3.2 ohms at 1472°F (800°C). If resistances are not as specified, replace appropriate A/F sensor. If resistances are as specified, go to next step.
  5. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, go to next step.
  6. Check fuel pressure. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If fuel pressure is not within specification, repair as necessary. If fuel pressure is within specification, go to next step.
  7. Check fuel injectors. See FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, repair as necessary. If problem does not exist, replace defective A/F sensor.
  8. Perform test drive confirmation, then go to next step. See «TEST DRIVE CONFIRMATION»(ref-2630-S25511347382000041000000).
  9. Clear and recheck for DTCs. If DTC P1130 and/or P1150 is displayed again, replace ECM. If neither DTC P1130 and P1150 are displayed again, go to next step.
  10. Vehicle either ran out of fuel or problem is intermittent. Check component and ECM connections.
  1. If using OBD-II scan tool, go to step 3. If using Toyota hand-held tester, connect hand-held tester to Data Link Connector (DLC) No. 3. (Scheme 2) Switch scan tool to CHECK mode and go to next step.
  2. Start and warm engine to normal operating temperature with all accessories off. Drive vehicle at 38-75 MPH with engine speed at 1600-3200 RPM for 3-5 minutes. Stop vehicle and allow to idle for one minute. If malfunction exists, MIL will illuminate.
  3. Start and warm engine to normal operating temperature. Drive vehicle at 38-75 MPH with engine speed at 1600-3200 RPM for 3-5 minutes. Stop vehicle and allow to idle for one minute. Turn ignition off. Repeat driving and idle part of test. If malfunction exists, MIL will illuminate.
  1. If other DTCs are displayed, diagnose and repair those DTCs first and retest system. If only DTC P1133 and/or P1153 is displayed, go to next step.
  2. Connect scan tool to Data Link Connector (DLC) No. 3. Start engine and increase engine speed to 2500 RPM for approximately 90 seconds. Using scan tool, monitor each A/F sensor output voltage. See «AIR/FUEL RATIO SENSOR VOLTAGE SPECIFICATIONS»(ref-2630-S19499502302000041000000) table. If voltage is as specified, go to next step. If voltage is not as specified, go to step 8. AIR/FUEL RATIO SENSOR VOLTAGE SPECIFICATIONS Application (1) Volts Using OBD-II Scan Tool Engine Idling 0.66 Engine Racing 0.76 Or More Driving Vehicle (2) 0.56 Or Less Using Toyota Hand-Held Tester Engine Idling 3.3 Engine Racing 3.8 Or More Driving Vehicle (2) 2.8 Or Less (1) Voltage should not remain constant at specification given. (2) Drive vehicle at 25 MPH or more, with engine speed at 1500 RPM or more, while opening and closing throttle valve.
  3. Check for open or short in wiring between ECM and suspect A/F sensor. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
  4. Disconnect suspect A/F sensor harness connector. Measure resistance between terminal B+ (Black wire) and HT (Blue wire) at A/F sensor connector (component side). (Scheme 4) Resistance should be.8-1.4 ohms at 68°F (20°C) and 1.8-3.2 ohms at 1472°F (800°C). If resistances are not as specified, replace appropriate A/F sensor. If resistances are as specified, go to next step.
  5. Ensure oil dipstick, oil filler cap, PCV system and all other air induction system components are intact and operating properly. If problem exists, repair as necessary. If problem does not exist, go to next step.
  6. Check fuel pressure. See FUEL SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If fuel pressure is not within specification, repair as necessary. If fuel pressure is within specification, go to next step.
  7. Check fuel injectors. See FUEL SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, repair as necessary. If problem does not exist, replace defective A/F sensor.
  8. Perform test drive confirmation, then go to next step. See «TEST DRIVE CONFIRMATION»(ref-2630-S09336565362000041000000).
  9. Clear and recheck for DTCs. If DTC P1133 and/or P1153 is displayed again, replace ECM. If neither DTC P1133 and P1153 are displayed again, go to next step.
  10. Vehicle either ran out of fuel or problem is intermittent. Check component and ECM connections.
  1. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe at ECM harness connector and measure voltage between ground and terminals No. 4 (Blue wire) and No. 3 (Blue wire) at ECM harness connector E11. (Scheme 1) If both voltages are 9-14 volts, replace ECM. If either voltage is not 9-14 volts, go to next step.
  2. Disconnect suspect A/F sensor harness connector. Measure resistance between terminal B+ (Black wire) and HT (Blue wire) at A/F sensor connector (component side). (Scheme 4) Resistance should be.8-1.4 ohms at 68°F (20°C) and 1.8-3.2 ohms at 1472°F (800°C). If resistances are not as specified, replace appropriate A/F sensor. If resistances are as specified, go to next step.
  3. Check for open or short in wiring between EFI main relay and A/F sensor, and between A/F sensor and ECM. See WIRING DIAGRAMS article. Repair as necessary.
  1. Check for spark at misfiring cylinder. See IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If spark is exists, go to next step. If spark is not exist, go to step 4.
  2. Check for open or short in White/Red wire between terminal No. 25 at ECM harness connector E12 and ignitor. (Scheme 1) If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
  3. Disconnect Black 10-pin ignitor harness connector. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe at ECM harness connector and measure voltage between ground and terminal No. 25 (White/Red wire) at ECM harness connector E12. (Scheme 1) If voltage is 4.5-5.5 volts, replace ignitor. If voltage is not 4.5-5.5 volts, replace ECM.
  4. Check for open or short in IGT1, IGT2 and IGT3 circuits between ECM and ignitor. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
  5. Access ECM behind glove box. Using DVOM, backprobe ECM connector and measure voltage between ground and terminals No. 11 (Gray wire), No. 12 (Brown/Yellow wire) and No. 13 (Light Green/Black wire) at ECM harness connector E12 while cranking engine. (Scheme 1) If all readings are.1-4.5 volts, go to next step. If any reading is not.1-4.5 volts, replace ECM.
  6. Disconnect Black 10-pin ignitor harness connector. Using DVOM, backprobe ECM harness connector and measure voltage between ground and terminals No. 11 (Gray wire), No. 12 (Brown/Yellow wire) and No. 13 (Light Green/Black wire) at ECM harness connector E12 while cranking engine. If all readings are.1-4.5 volts, go to next step. If any reading is not.1-4.5 volts, replace ECM.
  7. Turn ignition on. Measure voltage between ground and terminal No. 9 (Black/Red wire) at ignitor harness connector. (Scheme 13) 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 article.
  8. Check for open or short in wiring between ignition switch and ignition coil, and between ignition coil and ignitor. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
  9. Check ignition coil. See IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If problem exists, replace ignition coil. If problem does not exist, go to next step.
  10. Check EFI main relay. See MOTORS & RELAYS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, replace EFI main relay. If problem does not exist, go to next step.
  11. Check ignition ground circuit. If problem exists, repair as necessary. If problem does not exist, replace ignitor.

Scheme 13

Scheme 13
Scheme 13
  1. Check stoplight operation. If stoplights do not operate properly, repair as necessary and retest system. See appropriate wiring diagram in EXTERIOR LIGHTS article in ACCESSORIES & EQUIPMENT. If stoplights operate properly, go to next step.
  2. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between ground and terminal No. 15 (Green/White wire) at ECM harness connector E8. (Scheme 1) Voltage should be 7.5-14.0 volts with brake pedal depressed, and less than 1.5 volts with brake pedal released. If voltage is not as specified, go to next step. If voltage is as specified, problem is intermittent. Check component and ECM connections.
  3. Check for open or 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 ground and terminal No. 1 (Red/Black wire) at ECM harness connector E8. (Scheme 1) If voltage is 9-14 volts, replace ECM. If voltage is not 9-14 volts, go to next step.
  2. Remove and inspect EFI fuse (15-amp). EFI fuse is located in engine compartment fuse box. If fuse is blown, check for short to ground in wiring between EFI fuse and ECM. See WIRING DIAGRAMS article. Repair as necessary and replace fuse. If fuse is okay, check for open in wiring between EFI fuse and ECM. Repair as necessary.

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

  1. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between ground and specified terminal at ECM harness connector E9 with shift lever in appropriate position. See «PARK/NEUTRAL POSITION SWITCH VOLTAGE»(ref-2630-S38996217122000041000000) table. (Scheme 1) If voltage is as specified, replace ECM. If voltage is not as specified, go to next step. PARK/NEUTRAL POSITION SWITCH VOLTAGE Shift Lever Position (1) Terminal No. Volts Park & Neutral 2 Zero 3 Zero 12 Zero 20 Zero Reverse 2 9-14 3 Zero 12 Zero 20 9-14 Drive 2 Zero 3 Zero 12 Zero 20 9-14 2 2 Zero 3 9-14 12 Zero 20 9-14 Low 2 Zero 3 Zero 12 9-14 20 9-14 (1) Measure voltage between ground and terminal listed at ECM harness connector E9. (Scheme 1)
  2. Disconnect PNP switch harness connector. Check continuity between appropriate PNP switch terminals (component side) with shift lever in appropriate position. See «PARK/NEUTRAL POSITION SWITCH CONTINUITY»(ref-2630-S26316328012000041000000) table. (Scheme 14) If problem exists, replace PNP switch. If problem does not exist, go to next step. PARK/NEUTRAL POSITION SWITCH CONTINUITY Shift Lever Position Continuity Between Terminals No. Park 2 & 7; 5 & 6 Reverse 2 & 8 Neutral 2 & 9; 5 & 6 Drive 2 & 10 2 2 & 3 Low 2 & 4
  3. Check wiring between battery and PNP switch and between PNP switch and ECM. See WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.

Scheme 14

Scheme 14
Scheme 14

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