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Engine Control System Self-Diagnostics - V6: Diagnosis Toyota 4Runner III

Testing & Diagnostics 14 illustrations ~11047 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
P0100Mass Airflow (MAF) Meter Circuit
P0101Mass Airflow (MAF) Meter Circuit Range/Performance
P0110Intake Air Temperature (IAT) Sensor Circuit
P0115Engine Coolant Temperature (ECT) Sensor Circuit
P0116Engine Coolant Temperature (ECT) Sensor Circuit Range/Performance
P0120Throttle 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)
P0130Heated Oxygen Sensor No. 1 Circuit (Except Calif. Emissions)
P0133Heated Oxygen Sensor No. 1 Circuit Slow Response (Except Calif. Emissions)
P0135Heated Oxygen Sensor No. 1 Heater Circuit (Except Calif. Emissions)
P0136Heated Oxygen Sensor No. 2 Circuit
P0141Heated Oxygen Sensor No. 2 Heater Circuit
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
P0325Knock Sensor No. 1 Circuit
P0330Knock 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 (EVAP)
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 (3)Transmission Fluid Temperature Sensor Malfunction
P0750 (3)Shift Solenoid Valve No. 1 Malfunction
P0753 (3)Shift Solenoid Valve No. 1 Electrical Malfunction
P0755 (3)Shift Solenoid Valve No. 2 Malfunction
P0758 (3)Shift Solenoid Valve No. 2 Electrical Malfunction
P0770 (3)Lock-Up Solenoid Malfunction
P0773 (3)Lock-Up Solenoid Circuit Electrical Malfunction
P1130Air/Fuel Sensor Circuit Range/Performance (Calif. Emissions)
P1133Air/Fuel Sensor Circuit Response (Calif. Emissions)
P1135Air/Fuel Sensor Heater Circuit (Calif. Emissions)
P1300Ignitor Circuit
P1335Crankshaft Position (CKP) Sensor Circuit
P1520Stoplight Switch Signal Circuit (A/T Only)
P1600ECM BATT Circuit
P1700 (3)Vehicle Speed Sensor No. 2 Malfunction
P1780Park/Neutral Position (PNP) Switch Circuit
(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 ENGINE IMMOBILIZER SYSTEMS - 4RUNNER article in ACCESSORIES & EQUIPMENT. (3) These codes only apply to models with electronically controlled transmissions. For testing procedures, see appropriate ELECTRONIC CONTROLS article in AUTOMATIC TRANSMISSIONS.
(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 ENGINE IMMOBILIZER SYSTEMS - 4RUNNER article in ACCESSORIES & EQUIPMENT.
(3)These codes only apply to models with electronically controlled transmissions. For testing procedures, see appropriate ELECTRONIC CONTROLS article in AUTOMATIC TRANSMISSIONS.

DIAGNOSTIC TROUBLE CODE (DTC) IDENTIFICATION

DIAGNOSTIC TESTS

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

CAUTIONIf ECM replacement is instructed in following testing, always ensure ECM connectors and ground circuit are okay. If either are suspect, repair and repeat testing to confirm ECM malfunction. If ECM is replaced, ECM must be programmed with proper ignition key code for engine immobilizer system (if equipped). For programming procedures, see COMPUTER RELEARN PROCEDURES article in GENERAL INFORMATION.

Diagnosis & Repair

  1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 77) 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 11.0-25.1, go to step 5.
  2. Turn ignition off. Disconnect MAF meter harness connector. Turn ignition on. Measure voltage between ground and terminal No. 1 (White/Blue wire) at MAF meter harness connector. (Scheme 78) If voltage is 9-14 volts, go to next step. If voltage is not 9-14 volts, repair open in White/Blue wire between EFI main relay and MAF meter. See appropriate wiring diagram in 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 (Red/White wire) at ECM harness connector E10. (Scheme 79) If voltage is not 1.1-1.5 volts, go to next step. If voltage is 1.1-1.5 volts, replace ECM.
  4. Check for open or short in Red/White wire between MAF meter and ECM. See appropriate wiring diagram in 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 (Black/White wire) at ECM harness connector E10. (Scheme 79) If resistance is one ohm or less, go to next step. If resistance is greater than one ohm, replace ECM.
  6. Check for open in Black/White wire between MAF meter and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace MAF meter.

Scheme 77

Scheme 77
Scheme 77

Scheme 78

Scheme 78
Scheme 78

Scheme 79

Scheme 79
Scheme 79

Circuit Description

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

  1. Defective MAF meter.

Diagnostic Aids

After confirming DTC P0101, use scan tool to access CURRENT DATA to confirm mass airflow ratio. If ratio is 0.0 gm/sec., VG circuit may be open or shorted, or power source circuit may be open. If ratio is 11.0-25.1 gm/sec., E2G circuit may be open. Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.

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

  1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 77) Turn ignition on. Using scan tool, monitor IAT sensor temperature. If temperature displayed on scan tool is same as outside temperature, problem is intermittent. Check component and ECM connections. If temperature displayed on scan tool is -40°F (-40°C), go to next step. If temperature displayed on scan tool is 284°F (140°C) or more, go to step 4.
  2. Turn ignition off. Disconnect MAF meter harness connector. Using a jumper wire, connect MAF meter harness connector terminals No. 4 (Yellow/Green wire) and No. 5 (Blue/Black wire). (Scheme 78) 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 (Blue/Black wire) and No. 22 (Yellow/Green wire) at ECM harness connector E10. (Scheme 79) If temperature displayed on scan tool is 284°F (140°C) or more, repair open in Yellow/Green wire and/or Blue/Black wire between MAF meter and ECM. See appropriate wiring diagram in 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 E10. (Scheme 79) Turn ignition on. If temperature displayed on scan tool is -40°F (-40°C), repair short in Yellow/Green wire between MAF meter and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. If temperature displayed on scan tool is not -40°F (-40°C), replace ECM.

Note. ECT sensor wiring (circuit THW) between ECM and ECT sensor changes color at in-line harness connector EC1. In-line harness connector EC1 is located a near ECT sensor. It is a Green/Yellow wire between ECT sensor and in-line harness connector EC1 and a Green wire between in-line harness connector EC1 and ECM. ECT sensor wiring (circuit E2) between ECM and ECT sensor changes color at in-line harness connector EC1. It is a Brown/Black wire between ECT sensor and in-line harness connector EC1 and a Blue/Black wire between in-line harness connector EC1 and ECM.

  1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 77) Turn ignition on. Using scan tool, monitor ECT sensor temperature. If temperature displayed on scan tool is same as actual coolant temperature, problem is intermittent. Check component and ECM connections. If temperature displayed on scan tool is -40°F (-40°C), go to next step. If temperature displayed on scan tool is 284°F (140°C) or more, go to step 4.
  2. Turn ignition off. Disconnect ECT sensor harness connector (2-pin harness connector with Green/Yellow wire and Brown/Black 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 (Blue/Black wire) and No. 14 (Green wire) at ECM harness connector E10. (Scheme 79) If temperature displayed on scan tool is 284°F (140°C) or more, repair open in wiring between ECT sensor and ECM. See appropriate wiring diagram in 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 E10. (Scheme 79) Turn ignition on. If temperature displayed on scan tool is -40°F (-40°C), repair short in wiring between ECT sensor and ECM. See appropriate wiring diagram in 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 77) 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. 2 (Green/Black 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 (Black/Yellow wire) and No. 18 (Blue/Black wire) at ECM harness connector E10. (Scheme 79) 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 Black/Yellow wire between TP sensor and ECM. See appropriate wiring diagram in 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 (Green/Black wire) and No. 18 (Blue/Black wire) at ECM harness connector E10. (Scheme 79) If voltage is 4.5-5.5 volts, repair open in Green/Black wire between TP sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. If voltage is not 4.5-5.5 volts, replace ECM.

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

  1. Defective Throttle Position (TP) sensor.

After confirming DTC P0121, use scan tool to access CURRENT DATA to confirm throttle valve opening percentage with throttle open and closed. If percentage displayed on scan tool is always zero percent, VC circuit may be open, or VTA circuit may be open or shorted. If percentage displayed on scan tool is always 100 percent, check for open in E2 circuit. Using scan tool, read freeze frame data. Freeze frame records engine conditions when malfunction is detected.

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

  1. If 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 77) Start and warm engine to normal operating temperature. Using scan tool, monitor heated oxygen sensor No. 1. Snap accelerate engine to about 4000 RPM 3 times. Heated oxygen sensor No. 1 should indicate a rich signal (.45 volt or more) at least once. If a rich signal is indicated for heated oxygen sensors No. 1 at least once, go to step 9. If 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 heated oxygen sensor No. 1 and ECM. If problem does not exists, go to next step. If problem exists, repair wiring as necessary. See appropriate wiring diagram in 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-91236-S30656010352001030600000). 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 SYSTEM 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 SYSTEM 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 No. 1.
  9. Perform test drive confirmation, then go to next step. See «TEST DRIVE CONFIRMATION»(ref-91236-S03680406102001030600000) under DTC P0130: 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. (Scheme 77) Start engine and increase engine speed to 2500 RPM for approximately 90 seconds. Using scan tool, monitor A/F sensor output voltage. See «AIR/FUEL RATIO SENSOR SPECIFICATIONS»(ref-91236-S07280617202001030600000) table. If voltage is as specified, go to next step. If voltage is not as specified, go to step 9. AIR/FUEL RATIO SENSOR SPECIFICATIONS Application (1) Voltage 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 A/F sensor. See appropriate wiring diagram in WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
  4. Disconnect A/F sensor harness connector. Measure resistance between terminal B+ (White/Blue wire) and HT (Blue wire) at A/F sensor connector (component side). (Scheme 80) Resistance should be.8-1.4 ohms at 68°F (20°C) and 1.8-3.2 ohms at 1472°F (800°C). If resistance is not as specified, replace A/F sensor. If resistance is 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 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 SYSTEM 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-91236-S03680406102001030600000) under DTC P1130: 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 80

Scheme 80
Scheme 80

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 77) 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 is displayed, go to next step.
  2. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 77) Start engine and increase engine speed to 2500 RPM for approximately 90 seconds. Let engine idle. Using scan tool, monitor 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 sensor No. 1. See appropriate wiring diagram in 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 SYSTEM 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 SYSTEM in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, repair as necessary. If problem does not exist, replace heated oxygen sensor No. 1.
  7. Perform test drive confirmation, then go to next step. See «TEST DRIVE CONFIRMATION»(ref-91236-S03680406102001030600000).
  8. Clear and recheck for DTCs. If DTC P0130 is displayed again, replace ECM. If DTC P0130 is not 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 is displayed, go to next step.
  2. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 77) Start engine and increase engine speed to 2500 RPM for approximately 90 seconds. Let engine idle. Using scan tool, monitor heated oxygen sensor 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 sensor No. 1. See appropriate wiring diagram in 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 SYSTEM 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 SYSTEM 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-91236-S03680406102001030600000) under DTC P0130: HEATED OXYGEN SENSOR NO. 1 CIRCUIT (EXCEPT CALIF. EMISSIONS).
  8. Clear and recheck for DTCs. If DTC P0133 is displayed again, replace ECM. If DTC P0133 is not 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 and measure voltage between ground and terminal No. 4 (Pink/Blue wire) at ECM harness connector E10. (Scheme 79) 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 heated oxygen sensor No. 1 harness connector. Measure resistance between terminals B+ (White/Blue wire) and HT (Pink/Blue wire) at heated oxygen sensor No. 1 connector (component side). (Scheme 81) Resistance should be 11-16 ohms at 68°F (20°C) and 23-32 ohms at 1472°F (800°C). If resistance is not as specified, replace heated oxygen sensor No. 1. If resistance is as specified, go to next step.
  3. Repair wiring between ECM and heated oxygen sensor No. 1, or between heated oxygen sensor No. 1 and EFI main relay. See appropriate wiring diagram in WIRING DIAGRAMS article.

Scheme 81

Scheme 81
Scheme 81
  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 appropriate wiring diagram in 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 77) 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. 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 and measure voltage at ECM harness connector and measure voltage between ground and terminal No. 9 (Red/White wire) at ECM harness connector E12. (Scheme 79) 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. Measure resistance between terminals HT (Red/White wire) and B+ (White/Blue wire) at heated oxygen sensor No. 2 connector (component side). (Scheme 81) Resistance should be 11-16 ohms at 68°F (20°C) and 23-32 ohms at 1472°F (800°C). If resistance is not as specified, replace heated oxygen sensor No. 2. If resistance is as specified, go to next step.
  3. Repair wiring between ECM and heated oxygen sensor No. 2, or between heated oxygen sensor No. 2 and EFI main relay. See appropriate wiring diagram in WIRING DIAGRAMS article.
  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 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 sensor(s). If problem does not exist, go to next step.
  4. Check spark and ignition system. See IGNITION CHECKS 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 SYSTEM 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. (Scheme 77) 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 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 appropriate wiring diagram in WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace heated oxygen sensor No. 1.
  9. Perform test drive confirmation, then go to next step. See «TEST DRIVE CONFIRMATION»(ref-91236-S03680406102001030600000) under DTC P0130: 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 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. 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 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 sensor(s). If problem does not exist, go to next step.
  4. Check spark and ignition system. See IGNITION CHECKS 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 SYSTEM 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. (Scheme 77) Start engine and increase engine speed to 2500 RPM for approximately 90 seconds. Using scan tool, monitor A/F sensor output voltage. See «AIR/FUEL RATIO SENSOR SPECIFICATIONS»(ref-91236-S11545802172001030600000) table. If voltage is not as specified, go to next step. If voltage is as specified, go to step 9. AIR/FUEL RATIO SENSOR SPECIFICATIONS Application (1) Voltage 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 appropriate wiring diagram in 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-91236-S03680406102001030600000) under DTC P1130: 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.

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

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

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

  1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 77) 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-91236-S09443623612001030600000) 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-91236-S40209825612001030600000). If problem does not exist, go to next step.
  2. Check spark and ignition system. See IGNITION CHECKS 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 connector and measure voltage between ground and fuel injector terminals at appropriate ECM harness connector. See «IDENTIFYING FUEL INJECTOR TERMINALS»(ref-91236-S01134670752001030600000) table. (Scheme 79) 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 5 (1) Red 2 6 (1) White 3 1 (2) Green 4 2 (2) Red/Black 5 3 (2) Blue 6 4 (2) Yellow (1) Terminal are located in ECM harness connector E10. (Scheme 79) (2) Terminals are located in ECM harness connector E9. (Scheme 79)
  4. Disconnect fuel injector harness connector at misfiring cylinder. Measure resistance between fuel injector terminals (component side). Resistance should be 13.8 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 appropriate wiring diagram in WIRING DIAGRAMS article. If problem exists, repair as necessary. If problem does not exist, repair open or short in injector power source circuit. See appropriate wiring diagram in WIRING DIAGRAMS article.
  6. Check fuel pressure. See FUEL SYSTEM 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 SYSTEM 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 sensor(s). If problem does not exist, go to next step.
  9. Check engine compression. See BASIC DIAGNOSTIC PROCEDURES - V6 & V8 article. If engine compression is okay, check valve clearance. See ON-VEHICLE ADJUSTMENTS - V6 & V8 article. If valve clearance is okay, it may be necessary to check valve timing. See appropriate article in ENGINES.

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

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

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

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

  1. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 77) Disconnect EB1 connector. EB1 connector is an in-line harness connector located on front center of engine, behind timing belt cover. EB1 connector is a 3-pin connector (Dark Gray on one side and Gray on the other). Remove, switch and install terminals No. 1 and 2 from male connector. (Scheme 82) Connect EB1 connector. Turn ignition on. Clear DTCs. Start and warm engine to normal operating temperature. Snap accelerate engine to about 4000 RPM 3 times. Retrieve DTCs. If same DTC is repeated, go to next step. If DTC changed, go to step 3.
  2. Check for open or short in wiring between EB1 connector and ECM. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM. Ensure EB1 male connector terminals are returned to their original position.
  3. Check for open or short in wiring between EB1 connector and knock sensor(s). To access harness, it may be necessary to remove intake manifold. See KNOCK SENSOR under ENGINE SENSORS & SWITCHES in REMOVAL, OVERHAUL & INSTALLATION - V6 & V8 article. If problem exists, repair wiring as necessary. If problem does not exist, replace knock sensor. Ensure EB1 male connector terminals are returned to their original position.

Scheme 82

Scheme 82
Scheme 82
  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 appropriate wiring diagram in WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, remove and inspect CKP sensor. Also inspect signal plate. Replace CKP sensor and/or signal plate as necessary. If both components are okay, replace ECM.
  1. Disconnect CMP sensor harness connector. Measure resistance between CMP sensor connector terminals (component side). Resistance should be 835-1400 ohms (cold sensor) or 1060-1645 ohms (hot sensor). If resistance is not as specified, replace CMP sensor. If resistance is as specified, go to next step.
  2. Check for open or short in wiring between ECM and CMP sensor. See appropriate wiring diagram in 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: HEATED OXYGEN SENSOR NO. 1 CIRCUIT (EXCEPT CALIF. EMISSIONS)»(ref-91236-S27057665202001030600000) . 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-91236-S31072318182001030600000) . 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-91236-S32556551622001030600000) . 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-91236-S31072318182001030600000) . 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 disconnect 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 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 (Green/Black wire) and No. 18 (Blue/Black wire) at ECM harness connector E10. (Scheme 79) 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 (Yellow wire) at ECM harness connector E14 and terminal No. 18 (Blue/Black wire) at ECM harness connector E10. (Scheme 79) Disconnect vacuum hose from vapor pressure sensor. Connect a vacuum pump to vapor pressure sensor. Voltage should be 3.0-3.6 volts without vacuum applied, and.5 volt or less with 1.8 in. Hg applied. If voltage is as specified, go to step 12. If voltage is not as specified, go to next step.
  11. Check for an open or short in wiring between vapor pressure sensor and ECM. See appropriate wiring diagram in 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 (vacuum hose from fuel tank-to-charcoal canister). (Scheme 83) Ensure fuel cap is installed properly. Using a vacuum pump, apply.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 83

Scheme 83
Scheme 83

Diagnosis & Repair (Using Toyota Hand-Held Tester)

  1. Check EVAP VSV, vapor pressure sensor VSV and vapor pressure sensor harness 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 (Green/Black wire) and No. 18 (Blue/Black wire) at ECM harness connector E10. (Scheme 79) 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 (Yellow wire) at ECM harness connector E14 and terminal No. 18 (Blue/Black wire) at ECM harness connector E10. (Scheme 79) Disconnect vacuum hose from vapor pressure sensor. Connect a vacuum pump to vapor pressure sensor. Voltage should be 3.0-3.6 volts without vacuum applied, and.5 volt or less with 1.8 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 an open or short in wiring between vapor pressure sensor and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace vapor pressure sensor.
  6. Connect hand-held tester to Data Link Connector (DLC) No. 3. (Scheme 77) Turn ignition on. Using scan tool, select ACTIVE TEST mode. Disconnect vacuum hose from port "C" at charcoal canister. (Scheme 84) Start engine. Connect a vacuum gauge to disconnected vacuum hose. When EVAP VSV is activated by hand-held tester, vacuum should exist. When EVAP VSV is not activated, vacuum should not exist. If vacuum is as specified, go to step 10. If vacuum is not as specified, go to next step.
  7. Check vacuum hose between intake manifold and EVAP VSV, and vacuum 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 operation. 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 an open or short in wiring between EFI main relay and EVAP VSV, and between EVAP VSV and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.
  10. Turn ignition on. Using hand-held tester, select ACTIVE TEST mode. Apply air pressure to vapor pressure sensor VSV port "E". (Scheme 85) When vapor pressure sensor VSV is activated by hand-held tester, air should flow from port "F". When vapor pressure sensor VSV is not activated, air should flow from port "G". If vapor pressure sensor VSV operates as specified, go to step 13. If vapor pressure sensor VSV does not operate as specified, go to next step.
  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 appropriate wiring diagram in WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.
  13. Disconnect vapor pressure sensor VSV harness connector. Start engine. Using hand-held tester, select ACTIVE TEST mode. Using DVOM, backprobe ECM harness connector and measure voltage between terminal No. 17 (Yellow wire) at ECM harness connector E14 and terminal No. 18 (Blue/Black wire) at ECM harness connector E10. (Scheme 79) With EVAP VSV activated by hand-held tester, voltage should be 2 volts or less. If voltage is as specified, go to step 15. If voltage is not as specified, go to next step.
  14. Check vacuum hose between charcoal canister and vapor pressure sensor VSV, and vacuum hose between vapor pressure sensor and vapor pressure sensor VSV. If problem exists, repair vacuum hoses as necessary. If problem does not exist, go to next step.
  15. Remove fuel cap. Disconnect vapor pressure sensor VSV harness connector. Using hand-held tester, select ACTIVE TEST mode. Start engine. Using DVOM, backprobe ECM harness connector and measure voltage between terminal No. 17 (Yellow wire) at ECM harness connector E14 and terminal No. 18 (Blue/Black wire) at ECM harness connector E10 5 seconds after switching EVAP VSV from on to off. If voltage is 2.5 volts or less, replace charcoal canister. If voltage is more than 2.5 volts, go to next step.
  16. Perform appropriate fuel EVAP system test. See FUEL EVAPORATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS in SYSTEM & COMPONENT TESTING - V6 & V8 article. If problem exists, repair as necessary. If problem does not exist, replace ECM.

Scheme 84

Scheme 84
Scheme 84

Scheme 85

Scheme 85
Scheme 85

Diagnosis & Repair (Using OBD-II Scan Tool)

  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 (Green/Black wire) and No. 18 (Blue/Black wire) at ECM harness connector E10. (Scheme 79) 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 (Yellow wire) at ECM harness connector E14 and terminal No. 18 (Blue/Black wire) at ECM harness connector E10. (Scheme 79) Disconnect vacuum hose from vapor pressure sensor. Vapor pressure sensor is mounted on firewall, near brake booster. Connect a vacuum pump to vapor pressure sensor. Voltage should be 3.0-3.6 volts without vacuum applied, and.5 volt or less with 1.8 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 appropriate wiring diagram in 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 86) 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 (White/Green wire) at ECM harness connector E10. (Scheme 79) 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 appropriate wiring diagram in 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 85) 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 (Yellow/Green wire) at ECM harness connector E14. (Scheme 79) 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 appropriate wiring diagram in WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.

Scheme 86

Scheme 86
Scheme 86
  1. Access ECM behind glove box. Turn ignition on. Using DVOM, backprobe ECM harness connector and measure voltage between terminals No. 2 (Green/Black wire) and No. 18 (Blue/Black wire) at ECM harness connector E10. (Scheme 79) 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 (Yellow wire) at ECM harness connector E14 and terminal No. 18 (Blue/Black wire) at ECM harness connector E10. (Scheme 79) Disconnect vacuum hose from vapor pressure sensor. Vapor pressure sensor is mounted on firewall, near brake booster. Connect a vacuum pump to vapor pressure sensor. Voltage should be 3.0-3.6 volts without vacuum applied, and.5 volt or less with 1.8 in. Hg applied. If voltage is as specified, replace ECM. If voltage is not as specified, go to next step.
  3. Check for open or short in wiring between vapor pressure sensor and ECM. See appropriate wiring diagram in 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. Raise and support one rear wheel. Turn ignition on. Shift transaxle lever into Neutral. Using DVOM, backprobe ECM harness connector and measure voltage between ground and terminal No. 22 (Green/Orange wire) at ECM harness connector E12. (Scheme 79) Observe voltage reading while rotating rear wheel. Voltage should pulse between zero volts and 4-6 volts. If voltage is as specified, replace ECM. If voltage is not as specified, repair open or short in wiring between instrument cluster and ECM. See appropriate wiring diagram in 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 77) Note engine RPM. Using a jumper wire, connect terminals TE1 and E1 at DLC No. 1 in engine compartment. (Scheme 87) 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 E9. (Scheme 79) Turn ignition on. Measure voltage between ground and terminals No. 16 (Brown/Red wire) and No. 15 (Black/Red wire) at ECM harness connector E9. 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 88) If resistance is not 17-25 ohms (cold) or 21.5-29.5 ohms (hot), replace IAC valve. If resistance is 17-25 ohms (cold) or 21.5-29.5 ohms (hot), repair open or short in wiring between IAC valve and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article.
  4. Check IAC valve operation. See IDLE CONTROL SYSTEM 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 87

Scheme 87
Scheme 87

Scheme 88

Scheme 88
Scheme 88
  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 77) 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 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 is displayed, go to next step.
  2. Connect scan tool to Data Link Connector (DLC) No. 3. (Scheme 77) Start engine and increase engine speed to 2500 RPM for approximately 90 seconds. Using scan tool, monitor A/F sensor output voltage. See «AIR/FUEL RATIO SENSOR SPECIFICATIONS»(ref-91236-S06531389002001030600000) table. If voltage is as specified, go to next step. If voltage is not as specified, go to step 8. AIR/FUEL RATIO SENSOR SPECIFICATIONS Application (1) Voltage 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 appropriate wiring diagram in WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
  4. Disconnect A/F sensor harness connector. Measure resistance between terminal B+ (White/Blue wire) and HT (Red wire) at A/F sensor connector (component side). (Scheme 80) Resistance should be.8-1.4 ohms at 68°F (20°C) and 1.8-3.2 ohms at 1472°F (800°C). If resistance is not as specified, replace A/F sensor. If resistance is 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 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 SYSTEM 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-91236-S02981590832001030600000).
  9. Clear and recheck for DTCs. If DTC P1130 is displayed again, replace ECM. If DTC P1130 is not displayed again, go to next step.
  10. Vehicle either ran out of fuel or problem is intermittent. Check component and ECM connections.
  1. If using OBD-II scan tool, go to step 3. If using Toyota hand-held tester, connect hand-held tester to Data Link Connector (DLC) No. 3. (Scheme 77) 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 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 A/F sensor output voltage. See «AIR/FUEL RATIO SENSOR SPECIFICATIONS»(ref-91236-S23031536942001030600000) table. If voltage is as specified, go to next step. If voltage is not as specified, go to step 8. AIR/FUEL RATIO SENSOR SPECIFICATIONS Application (1) Voltage 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 A/F sensor. See appropriate wiring diagram in WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, go to next step.
  4. Disconnect A/F sensor harness connector. Measure resistance between terminal B+ (White/Blue wire) and HT (Blue wire) at A/F sensor connector (component side). (Scheme 80) Resistance should be.8-1.4 ohms at 68°F (20°C) and 1.8-3.2 ohms at 1472°F (800°C). If resistance is not as specified, replace A/F sensor. If resistance is 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 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 SYSTEM 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-91236-S31947996492001030600000).
  9. Clear and recheck for DTCs. If DTC P1133 is displayed again, replace ECM. If DTC P1133 is not 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 terminal No. 4 (Blue wire) at ECM harness connector E10. (Scheme 79) If voltage is 9-14 volts, replace ECM. If voltage is not 9-14 volts, go to next step.
  2. Disconnect A/F sensor harness connector. Measure resistance between terminal B+ (White/Blue wire) and HT (Blue wire ) at A/F sensor connector (component side). (Scheme 80) Resistance should be.8-1.4 ohms at 68°F (20°C) and 1.8-3.2 ohms at 1472°F (800°C). If resistance is not as specified, replace A/F sensor. If resistance is 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 appropriate wiring diagram in WIRING DIAGRAMS article. Repair as necessary.
  1. Check for spark at misfiring cylinder. See IGNITION CHECKS 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 Black/Yellow wire between terminal No. 25 at ECM harness connector E9 and ignitor. (Scheme 79) 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 (Black/Yellow wire) at ECM harness connector E9. (Scheme 79) 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 appropriate wiring diagram in 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 (Black/Blue wire), No. 12 (Blue/Yellow wire) and No. 13 (Green/White wire) at ECM harness connector E9 while cranking engine. (Scheme 79) 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 (Black/Blue wire), No. 12 (Blue/Yellow wire) and No. 13 (Green/White wire) at ECM harness connector E9 while cranking engine. If all readings are.1-5.0 volts, go to next step. If any reading is not.1-5.0 volts, replace ECM.
  7. Turn ignition on. Measure voltage between ground and terminal No. 9 (Black/Red wire) at ignitor harness connector. (Scheme 89) 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 appropriate wiring diagram in 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 CHECKS 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 89

Scheme 89
Scheme 89
  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 E14. (Scheme 79) Voltage should be 7.5-14.0 volts with brake pedal depressed, and less than 1.5 volts with brake pedal released. If voltage is not as specified, go to next step. If voltage is as specified, problem is intermittent. Check component and ECM connections.
  3. Check for short in wiring between ECM and stoplight switch. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.
  1. Turn ignition off. Access ECM behind glove box. Using DVOM, backprobe ECM harness connector and measure voltage between ground and terminal No. 1 (Blue/Red wire) at ECM harness connector E14. (Scheme 79) 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 (20-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 appropriate wiring diagram in 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 from 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 E12 with shift lever in appropriate position. See «PARK/NEUTRAL POSITION SWITCH VOLTAGE»(ref-91236-S22949972262001030600000) table. (Scheme 79) 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 Terminal No. Volts Park & Neutral 2 Zero 3 Zero 12 Zero 20 Zero Reverse 2 (1) 9-14 3 Zero 12 Zero 20 (1) 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) Voltage may be slightly less due to lighting of reverse lights.
  2. Disconnect PNP switch harness connector. Check continuity between appropriate PNP switch terminals (component side) with shift lever in appropriate position. See «PARK/NEUTRAL POSITION SWITCH CONTINUITY»(ref-91236-S42361748752001030600000) table. (Scheme 90) 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 4 & 7; 5 & 6 Reverse 4 & 8 Neutral 4 & 10; 5 & 6 Drive 4 & 9 2 2 & 4 Low 3 & 4
  3. Check wiring between battery and PNP switch and between PNP switch and ECM. See appropriate wiring diagram in WIRING DIAGRAMS article. If problem exists, repair wiring as necessary. If problem does not exist, replace ECM.

Scheme 90

Scheme 90
Scheme 90

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