Engine Controls - System/component Tests: Other Toyota Corolla VII

Power & Ground Circuits

For testing of Engine Control Module (ECM) power and ground circuits, see PIN VOLTAGE CHART S article. See ECM LOCATION table for identifying ECM mounting locations.

ECM LOCATION

CAMSHAFT POSITION SENSOR

Camshaft position sensor is a pick-up coil located in the distributor. For checking of pick-up coil, see PICK-UP COIL RESISTANCE and PICK-UP COIL AIR GAP under IGNITION CHECKS (DISTRIBUTOR TYPE IGNITION SYSTEM) in BASIC TESTING article.

CRANKSHAFT POSITION SENSOR

For testing crankshaft position sensor, see CRANKSHAFT POSITION SENSOR under IGNITION CHECKS (DISTRIBUTOR TYPE IGNITION SYSTEM) in BASIC TESTING article.

ENGINE COOLANT TEMPERATURE (ECT) SENSOR

1. Ensure ignition is off. Disconnect electrical connector from ECT sensor. See «ENGINE COOLANT TEMPERATURE (ECT) SENSOR LOCATION»(ref-21984-S27107920502001010300000) table. To verify wire colors for proper sensor identification, see appropriate wiring diagram in WIRING DIAGRAMS article. NOTE: The ECT sensor may be also identified using appropriate illustration in «THEORY/OPERATION»(ref-21907) article.
2. Using ohmmeter, check resistance between electrical terminals on ECT sensor. Resistance should be within specification at designated temperature. (Scheme 31) Replace ECT sensor if resistance is not within specification.

ENGINE COOLANT TEMPERATURE (ECT) SENSOR LOCATION

Scheme 31

HEATED OXYGEN SENSOR

See OXYGEN SENSOR under ENGINE SENSORS & SWITCHES.

INTAKE AIR TEMPERATURE SENSOR

1. Ensure ignition is off. Disconnect electrical connector from intake air temperature sensor. Intake air temperature sensor is located in air intake, near air filter. NOTE: Intake air temperature sensor may be also identified using appropriate illustration in «THEORY/OPERATION»(ref-21907) article.
2. Remove intake air temperature sensor. Place threaded end of intake air temperature sensor and thermometer in container of water. Attach ohmmeter between electrical terminals on intake air temperature sensor.
3. Heat water and note that resistance is within specification in relation to temperature. (Scheme 31) Replace intake air temperature sensor if resistance is not within specification.

KNOCK SENSOR

Note. Knock sensor may also be referred to as knock sensor No. 1.

1.8L 7A-FE

1. Knock sensor is located on the cylinder block. (Scheme 31) Remove knock sensor from cylinder block before testing. See REMOVE/INSTALL/OVERHAUL article.
2. Using ohmmeter, check that no continuity exists between electrical terminal of knock sensor and body of knock sensor. Replace knock sensor if continuity exists.

Scheme 32

MANIFOLD ABSOLUTE PRESSURE (MAP) SENSOR

1. Ensure ignition is off. To check MAP sensor supply voltage, disconnect electrical connector from MAP sensor. See «MAP SENSOR LOCATION»(ref-21984-S14870273142001010300000) table. NOTE: MAP sensor may also be identified using appropriate illustration in «THEORY/OPERATION»(ref-21907) article. The MAP sensor has a vacuum hose connected to it and may be identified by wire colors. See appropriate wiring diagram in WIRING DIAGRAMS article. MAP SENSOR LOCATION Application Location Corolla Passenger's Side Of Engine Compartment, On Firewall, Near Wiper Motor
2. Turn ignition on. Using voltmeter, check MAP sensor supply voltage between terminals VC or VCC on wiring harness side of electrical connector for MAP sensor. (Scheme 33) The VC or VCC and E2 terminals are the 2 outer terminals on all models. DO NOT use the center terminal.
3. The MAP sensor supply voltage should be 4.5-5.5 volts. If MAP sensor supply voltage is not within specification, check wiring circuit. See appropriate wiring diagram in WIRING DIAGRAMS article. If MAP sensor supply voltage is within specification, turn ignition off. Reinstall electrical connector on MAP sensor.
4. To check MAP sensor output voltage, turn ignition on. Disconnect vacuum hose for MAP sensor from intake manifold. Connect voltmeter between terminals PIM and E2 on Engine Control Module (ECM). (Scheme 32) See «ECM LOCATION»(ref-21984-S01911675822001010300000) table. See «TERMINAL & WIRE COLOR IDENTIFICATION»(ref-21984-S00219462742001010300000) table. ECM LOCATION Model Location Corolla Bottom Center Of Instrument Panel, In Front Of Console TERMINAL & WIRE COLOR IDENTIFICATION Application & Terminal Wire Color PIM Light Green/Red E2 Brown
5. Measure and record output voltage under ambient atmospheric pressure. Attach vacuum pump to MAP sensor.
6. Apply vacuum in specified increments and measure MAP sensor output voltage drop at each increment. See «MAP SENSOR OUTPUT VOLTAGE DROP SPECIFICATIONS»(ref-21984-S38948583042001010300000) table. Replace MAP sensor if output voltage drop is not within specification.

MAP SENSOR OUTPUT VOLTAGE DROP SPECIFICATIONS

Scheme 33

Scheme 34

OXYGEN SENSOR

1. Two oxygen sensors are used. One non-heated oxygen sensor is on exhaust pipe before catalytic converter and another heated oxygen sensor is on exhaust pipe behind catalytic converter.
2. If problem exists with either oxygen sensor, a diagnostic trouble code will be stored in Engine Control Module (ECM). For diagnostic trouble code diagnosis, see appropriate article listed below: «TESTS W/CODES - 1.6L»(ref-21945) «TESTS W/CODES - 1.8L»(ref-21946)
3. To test the heater on heated oxygen sensor, disconnect electrical connector for heated oxygen sensor and note heated oxygen sensor terminals. (Scheme 43)
4. Electrical connector for heated oxygen sensor on exhaust pipe behind catalytic converter is a Dark Gray 4-pin electrical connector located below passenger's side front seat, below the carpet, near center console.
5. Using ohmmeter, check resistance between heated oxygen sensor terminals +B and HT. (Scheme 43) Replace heated oxygen sensor if resistance is not 11-16 ohms at 68°F (20°C).

Scheme 35

A/T Models

If problem exists with Park/Neutral Position (PNP) switch or circuit, a diagnostic trouble Code P1780 will be stored in the Engine Control Module (ECM). For diagnostic trouble code diagnosis, see appropriate article listed below

TESTS W/CODES - 1.6L

TESTS W/CODES - 1.8L

1. Disconnect electrical connector from Park/Neutral Position (PNP) switch, mounted on side of transmission/transaxle. Note terminal identification. (Scheme 36)
2. Using ohmmeter, check for continuity between specified terminals with shift lever in proper positions. See «PARK/NEUTRAL POSITION SWITCH SPECIFICATIONS»(ref-21984-S34142067662001010300000) table. If proper continuity cannot obtained, adjust or replace switch as necessary.

PARK/NEUTRAL POSITION SWITCH SPECIFICATIONS

Scheme 36

PICK-UP COILS

See PICK-UP COIL AIR GAP and PICK-UP COIL RESISTANCE under IGNITION CHECKS (DISTRIBUTOR TYPE IGNITION SYSTEM) in BASIC TESTING article.

THROTTLE POSITION (TP) SENSOR

1. Ensure ignition is off. Disconnect electrical connector from throttle position sensor on throttle body. Note terminal identification. (Scheme 37) NOTE: Some models require that vacuum be applied to throttle opener before checking throttle position sensor. See «THROTTLE POSITION SENSOR RESISTANCE SPECIFICATIONS»(ref-21984-S41110826442001010300000) table.
2. Insert specified thickness feeler gauge between throttle stop screw and throttle lever and check resistance or continuity. See «THROTTLE POSITION SENSOR RESISTANCE SPECIFICATIONS»(ref-21984-S41110826442001010300000) table. Replace or adjust throttle position sensor if not within specification.

Scheme 37

THROTTLE POSITION SENSOR RESISTANCE SPECIFICATIONS

VEHICLE SPEED SENSOR

1. Vehicle speed sensor is located on transmission/transaxle and contains a 3-pin electrical connector. Connect voltmeter and battery voltage and ground on electrical terminals of vehicle speed sensor. (Scheme 33)
2. While rotating vehicle speed sensor shaft, ensure voltage changes from zero to at least 11 volts. Voltage should change 4 times per revolution of the shaft. Replace vehicle speed sensor if voltage does not change as specified. Remove test equipment.

Scheme 38

Scheme 39

CIRCUIT OPENING RELAY

1. Ensure ignition is off. Remove circuit opening relay. See «CIRCUIT OPENING RELAY LOCATION»(ref-21984-S08595439312001010300000) table. NOTE: Circuit opening relay may also be identified using appropriate illustration in «THEORY/OPERATION»(ref-21907) article and wire color. See appropriate wiring diagram in WIRING DIAGRAMS article. CIRCUIT OPENING RELAY LOCATIONS Application Relay Location Corolla Bottom Center Of Instrument Panel, In Front Of Center Console, Near Driver's Side Of ECM
2. To test circuit opening relay continuity, using ohmmeter, check continuity between specified terminals. (Scheme 40)and (Scheme 41).
3. To test circuit opening relay operation, apply battery voltage and ground to relay and use ohmmeter to check continuity between specified terminals. (Scheme 40)and (Scheme 41). Replace circuit opening relay if defective.

Scheme 40

Scheme 41

EFI MAIN RELAY

Note. EFI main relay may also be referred to as EFI relay.

1. Ensure ignition is off. Remove EFI main relay. See «EFI MAIN RELAY LOCATION»(ref-21984-S39755249462001010300000) table. NOTE: The EFI main relay may also be identified using appropriate illustration in «THEORY/OPERATION»(ref-21907) article. EFI MAIN RELAY LOCATION Application Location Corolla In Large Fuse/Relay Box Near Driver's Side Front Corner Of Engine Compartment
2. To test EFI main relay continuity, using ohmmeter, check continuity between specified terminals. (Scheme 42)and (Scheme 43).
3. To test EFI main relay operation, apply battery voltage and ground to relay and use ohmmeter to check continuity between specified terminals. (Scheme 42)and (Scheme 43). Replace EFI main relay if defective.

Scheme 42

Scheme 43

FUEL PUMP RELAY

Note. Fuel pump relay may also be referred to as fuel pump control relay.

See CIRCUIT OPENING RELAY under RELAYS.

See EFI MAIN RELAY under RELAYS.

Fuel Pump Pressure

For fuel pump pressure testing, see BASIC TESTING article.

Fuel Injectors

1. Ensure ignition is off. Disconnect electrical connector at fuel injector. Using ohmmeter, check resistance between electrical terminals on fuel injector. Replace fuel injector if resistance is not within specification. See «FUEL INJECTOR RESISTANCE SPECIFICATIONS»(ref-21984-S40575479102001010300000) table.
2. To check fuel injector spray pattern and volume, remove fuel injector. See REMOVE/INSTALL/OVERHAUL article. Disconnect fuel hose from fuel filter outlet. Use Delivery Hose (09268-41046) to install fuel injector between fuel filter and pressure regulator. (Scheme 44)
3. Place fuel injector into a clean graduated container. Place vinyl tube on end of fuel injector to prevent fuel spillage.
4. Use scan tester to operate the fuel pump or apply battery voltage to electric fuel pump to pressurize the fuel system. See FUEL PRESSURE in «BASIC TESTING»(ref-21925) article.
5. Connect Fuel Injector Tester (09842-30070) to fuel injector for 15 seconds. (Scheme 45) Measure fuel injector volume and check spray pattern. Test each fuel injector 2-3 times. Replace fuel injector if fuel injector volume is not within specification. See «FUEL INJECTOR VOLUME SPECIFICATIONS»(ref-21984-S15297985702001010300000) table. NOTE: Ensure difference between fuel injector volume on all fuel injectors is within specification. See FUEL INJECTOR VOLUME SPECIFICATIONS table.
6. Disconnect fuel injector tester. Ensure fuel leakage from end of fuel injector is one drop or less in specified time. See «FUEL INJECTOR LEAKAGE SPECIFICATIONS»(ref-21984-S09380150812001010300000) table. Replace fuel injector if leakage exceeds specified amount.

FUEL INJECTOR RESISTANCE SPECIFICATIONS

FUEL INJECTOR VOLUME SPECIFICATIONS

FUEL INJECTOR LEAKAGE SPECIFICATIONS

Scheme 44

Scheme 45

Fuel Cut System

1. When testing fuel cut system, engine RPM must be monitored using scan tester. Connect scan tester to data link connector No. 3 for monitoring engine RPM. For connecting of scan tester, see appropriate application under IDLE SPEED & MIXTURE in «ADJUSTMENTS»(ref-21889) article.
2. Start and warm engine to normal operating temperature. Ensure the A/C and all accessories are off. Gradually increase engine RPM to maintain at least specified engine speed. See «FUEL CUT SYSTEM TESTING SPECIFICATIONS»(ref-21984-S37329931632001010300000) table. FUEL CUT SYSTEM TESTING SPECIFICATIONS Application Engine RPM Corolla 3500
3. Using stethoscope, check for fuel injector operating sound. Ensure when throttle lever is released, fuel injector stops operating momentarily and then resumes operating (fuel return RPM).
4. Ensure fuel return RPM is within specification. See «FUEL CUT SPECIFICATIONS»(ref-21984-S39203237642001010300000) table. Shut engine off. Remove test equipment.

FUEL CUT SPECIFICATIONS (1)

IDLE AIR CONTROL (IAC) VALVE

1. Warm engine to normal operating temperature. Ensure idle speed is within specification. See IDLE SPEED & MIXTURE in the «ADJUSTMENTS»(ref-21889) article.
2. Apply parking brake and place transmission/transaxle in Neutral. Install Jumper Wire (SST 09843-18020) between terminals TE1 and E1 of data link connector No. 1. (Scheme 46) Start engine and note RPM. NOTE: Data link connector No. 1 is located in engine compartment on all models except Previa. On Previa, data link connector No. 1 is located under driver's seat.
3. On Previa, engine RPM should increase to specified engine RPM for 5 seconds and then decrease approximately 200 RPM. See «IAC VALVE ENGINE SPEED TESTING SPECIFICATIONS»(ref-21984-S00215618592001010300000) table.
4. On all other models, engine RPM should increase to specified RPM for 5 seconds, and then return to idle. See «IAC VALVE ENGINE SPEED TESTING SPECIFICATIONS»(ref-21984-S00215618592001010300000) table. IAC VALVE ENGINE SPEED TESTING SPECIFICATIONS Application Engine RPM Corolla 900-1300
5. On all models, if engine RPM is not as specified, test IAC valve resistance and operation. If engine RPM is within specification, remove jumper wire. Turn ignition off.
6. To test IAC valve resistance, ensure ignition is off. Disconnect electrical connector from IAC valve, located on lower area of throttle body. Using ohmmeter, check resistance between terminal +B and each remaining terminal. (Scheme 47)
7. Replace IAC valve if resistance is not within specification. See «IAC VALVE RESISTANCE SPECIFICATIONS»(ref-21984-S23701884552001010300000) table. IAC VALVE RESISTANCE SPECIFICATIONS Application Ohms Cold (1) 17.0-24.5 Hot (2) 21.5-28.5 (1) Cold is with temperature of 14-122°F (-10 - 50°C). (2) Hot is with temperature of 122-212°F (50-100°C).
8. To test IAC valve operation, remove IAC valve from throttle body. Apply battery voltage to +B terminal on IAC valve. Apply battery ground to proper terminal and ensure valve opens and closes. (Scheme 48) Replace IAC valve if defective.
9. If IAC valve resistance is within specification and operates correctly, check wiring circuit between Engine Control Module (ECM) and IAC valve. See «ECM LOCATION»(ref-21984-S01911675822001010300000) table. See appropriate wiring diagram in WIRING DIAGRAMS article.

ECM LOCATION

Scheme 46

Scheme 47

Scheme 48

IGNITION SYSTEM

Note. For basic ignition checks, see BASIC TESTING article.

See KNOCK SENSOR under ENGINE SENSORS & SWITCHES.

EGR GAS TEMPERATURE SENSOR

See EGR GAS TEMPERATURE SENSOR under ENGINE SENSORS & SWITCHES.

EGR VACUUM MODULATOR

Note. When testing EGR vacuum modulator, it may be necessary to monitor engine RPM by using scan tester. For scan tester connections, see IDLE SPEED & MIXTURE in ADJUSTMENTS article.

1. Mark vacuum hose locations and disconnect vacuum hoses from EGR vacuum modulator. see scheme 21 Block ports "P" and "R" on EGR vacuum modulator. see scheme 20 NOTE: Ports "P" and "R" are the double ports on side of EGR vacuum modulator. Port "Q" is single port on side of EGR vacuum modulator.
2. Apply air pressure to port "Q". see scheme 20 Air should flow freely through air filter side of EGR vacuum modulator.
3. Start and operate engine at specified RPM. See «EGR VACUUM MODULATOR TESTING SPECIFICATIONS»(ref-21984-S03928614572001010300000) table. Repeat test procedures in steps 1) and 2). Strong resistance of airflow should be felt. Replace EGR vacuum modulator if strong resistance is not felt. Reconnect vacuum hoses to proper locations.

EGR VACUUM MODULATOR TESTING SPECIFICATIONS

EGR VACUUM SWITCHING VALVE (VSV)

Note. When testing EGR VSV, use proper illustration to determine component location. see scheme 21

1. Disconnect electrical connector from EGR VSV. Using ohmmeter, check that continuity exists between electrical terminals on EGR VSV and that resistance is within specification. See «EGR VSV RESISTANCE SPECIFICATIONS»(ref-21984-S03054146472001010300000) table. Replace EGR VSV if no continuity exists or resistance is not within specification.
2. Ensure no continuity exists between each electrical terminal and the body of EGR VSV body. Replace EGR VSV if continuity exists between electrical terminal and the body of EGR VSV.
3. Apply air pressure to port "E" without battery connected. (Scheme 49) Air pressure should flow through the air filter. Apply battery voltage and ground to electrical terminals on EGR VSV. (Scheme 49) Apply air pressure to port "E". Air pressure should now flow from port "F". Replace EGR VSV if defective.

EGR VSV RESISTANCE SPECIFICATIONS

Scheme 49

FUEL EVAPORATION SYSTEM

Note. Fuel evaporation systems contain different components depending on application. see scheme 21 When testing fuel evaporation system components, use illustration to determine component location.

EVAP Thermal Vacuum Valve

1. Drain cooling system. Remove EVAP TVV located in coolant passage. see scheme 21
2. Use cool water to cool threaded end of EVAP TVV to less than 95°F (35°C). Apply air pressure to top vacuum hose port on EVAP TVV. Ensure EVAP TVV is closed and air does not flow from lower vacuum hose port on EVAP TVV.
3. Heat water to greater than 129°F (54°C). Apply air pressure to top vacuum hose port on EVAP TVV. Ensure EVAP TVV is open and air flows from lower vacuum hose port on EVAP TVV. Replace EVAP TVV if defective. Apply thread sealant on threads of EVAP TVV and reinstall.

Charcoal Canister

1. Remove charcoal canister. Check for clogged filter and/or stuck check valve by applying light air pressure to port "A". (Scheme 50) Ensure air flows freely from other ports on charcoal canister.
2. Apply light air pressure to port "B". (Scheme 50) Ensure air does not flow from any other ports on charcoal canister. Replace charcoal canister if defective.
3. To clean charcoal canister filter, apply 43 psi (3 kg/cm 2 ) air pressure to port "A" while holding port "B" closed. Air should flow from remaining ports on charcoal canister. Ensure no activated carbon comes out of charcoal canister. DO NOT attempt to wash out charcoal canister.

Scheme 50

POSITIVE CRANKCASE VENTILATION (PCV)

1. Remove PCV valve. Apply air pressure to PCV valve at cylinder head side of PCV valve. Ensure air flows easily through PCV valve.
2. Apply air pressure to PCV valve at intake manifold side of PCV valve. Ensure air flows through PCV valve with some resistance. Replace PCV valve if valve does not function as described.

THROTTLE OPENER

1. Warm engine to normal operating temperature. Ensure idle speed is within specification. See IDLE SPEED & MIXTURE in the «ADJUSTMENTS»(ref-21889) article.
2. Disconnect and plug vacuum hose at throttle opener, located on side of throttle body. Start engine. Maintain engine speed at 2500 RPM. Release throttle and note engine speed. Engine speed should be within specification. See «THROTTLE OPENER SPECIFICATIONS»(ref-21984-S11065990342001010300000) table.
3. If engine speed is not within specification, rotate throttle opener adjusting screw until correct engine speed is obtained. (Scheme 51) Reinstall vacuum hose on throttle opener.

Scheme 51

THROTTLE OPENER SPECIFICATIONS (1)