Engine Controls - System/component Tests - 2.7L: Other Toyota T100 I

Power & Ground Circuits

For testing of power/ground circuits, see procedures in the PIN VOLTAGE CHART S article. See ECM LOCATION table for identifying ECM mounting locations.

ECM LOCATION

Note. Fig. (Scheme 18) or (Scheme 19) identifies ECM terminals which are used for performing tests on various components in this article.

Scheme 18

Scheme 19

AIRFLOW METER

Note. Airflow meter may be referred to as Volume Airflow (VAF) meter or Mass Airflow (MAF) meter.

1. Airflow meter resistance specifications is not available from manufacturer. To check airflow meter operation, ensure electrical connector is installed on airflow meter.
2. Connect voltmeter leads to proper terminals on airflow meter with electrical connector installed. (Scheme 20) Turn ignition on.
3. Apply air into airflow meter and note voltage reading. (Scheme 20) While air is being applied, voltage reading should fluctuate. Replace airflow meter if voltage reading does not fluctuate. Remove voltmeter.

Scheme 20

CRANKSHAFT POSITION SENSOR

For checking crankshaft position sensor, see CRANKSHAFT POSITION SENSOR under IGNITION CHECKS (DISTRIBUTOR TYPE IGNITION SYSTEM) in the BASIC TESTING - 2.7L article.

EGR GAS TEMPERATURE SENSOR

1. Remove EGR gas temperature sensor from side of EGR valve. Place threaded end of sensor and thermometer in container of oil.
2. Attach ohmmeter to electrical terminals. Heat oil and note resistance at specified temperature. See «EGR GAS TEMPERATURE SENSOR SPECIFICATIONS»(ref-21627-S28593449062001010300000) table. Replace EGR gas temperature sensor if resistance is not within specification.

EGR GAS TEMPERATURE SENSOR SPECIFICATIONS

ENGINE COOLANT TEMPERATURE (ECT) SENSOR

1. Ensure ignition is off. Disconnect electrical connector from ECT sensor. See «ENGINE COOLANT TEMPERATURE (ECT) SENSOR LOCATION»(ref-21627-S39249312682001010300000) table. To verify wire colors for proper sensor identification, see wiring diagram in the WIRING DIAGRAMS article. NOTE: The ECT may be also identified using appropriate illustration in the «THEORY/OPERATION - 2.7L»(ref-21690) article.
2. Using ohmmeter, check resistance between ECT sensor electrical terminals. Resistance should be within specification at designated temperature. (Scheme 21) Replace ECT sensor if resistance is not within specification.

ENGINE COOLANT TEMPERATURE (ECT) SENSOR LOCATION

Scheme 21

INTAKE AIR TEMPERATURE (IAT) 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 the «THEORY/OPERATION - 2.7L»(ref-21690) article.
2. Remove intake air temperature sensor. Place threaded end of intake air temperature sensor and thermometer in container of water. Attach ohmmeter between intake air temperature sensor electrical terminals.
3. Heat water and note that resistance is within specification in relation to temperature. (Scheme 21) Replace intake air temperature sensor if defective.

KNOCK SENSOR

1. Knock sensor(s) are located on the cylinder block. (Scheme 22) Remove knock sensor from cylinder block before testing. See the 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 22

PARK/NEUTRAL POSITION (PNP) SWITCH CIRCUIT

If problem exists with park/neutral position switch or circuit, a diagnostic trouble Code P1780 will be stored in the Engine Control Module (ECM). See the TESTS W/CODES - 2.7L article for accessing diagnostic trouble codes.

A/T Models

1. Disconnect electrical connector from park/neutral position switch, mounted on side of transmission or transaxle. Note terminal identification. (Scheme 23)
2. Using ohmmeter, check for continuity at specified terminals with gearshift in proper positions. See the «PARK/NEUTRAL POSITION SWITCH SPECIFICATIONS»(ref-21627-S28258757502001010300000) table. If proper continuity cannot obtained, adjust switch. Replace switch if proper continuity cannot be obtained.

PARK/NEUTRAL POSITION SWITCH SPECIFICATIONS

Scheme 23

OXYGEN SENSOR HEATER

1. A front oxygen sensor is used on exhaust pipe in front of catalytic converter and a rear oxygen sensor on exhaust pipe behind catalytic converter. Disconnect electrical connector from appropriate oxygen sensor and note oxygen sensor terminals. (Scheme 24)
2. Using ohmmeter, measure resistance between oxygen sensor terminals +B and HT. (Scheme 24) Replace oxygen sensor if resistance is not within specs. See the «OXYGEN SENSOR HEATER RESISTANCE SPECIFICATIONS»(ref-21627-S27609482932001010300000) table.

OXYGEN SENSOR HEATER RESISTANCE SPECIFICATIONS

Scheme 24

PICK-UP COILS

See PICK-UP COIL AIR GAP and PICK-UP COIL RESISTANCE under IGNITION CHECKS (DISTRIBUTOR TYPE IGNITION SYSTEM) in the BASIC TESTING - 2.7L article.

THROTTLE POSITION SENSOR

1. Turn ignition off. Disconnect electrical connector from Throttle Position Sensor (TPS) on throttle body. Note terminal identification. (Scheme 25) NOTE: Some models require that vacuum be applied to throttle opener before checking TPS. See «TPS RESISTANCE SPECIFICATIONS»(ref-21627-S42863853372001010300000) table.
2. Insert specified thickness feeler gauge between throttle stop screw and throttle lever and check resistance or continuity. See the «TPS RESISTANCE SPECIFICATIONS»(ref-21627-S42863853372001010300000) table. Replace or adjust TPS if not within specification.

Scheme 25

TPS RESISTANCE SPECIFICATIONS (1)

VEHICLE SPEED SENSOR

1. Vehicle speed sensor is located on rear of combination meter in instrument cluster. Connect ohmmeter between terminals "A" and "B". Terminals are located near vehicle speed sensor. (Scheme 26)or (Scheme 27).
2. Rotate speedometer cable shaft and note reading. Ohmmeter should deflect from continuity to no continuity 4 times per speedometer cable shaft revolution. Replace speedometer if reading does not deflect as specified.

Scheme 26

Scheme 27

4WD SWITCH

1. 4WD switch is located on passenger's side of transfer case. Remove switch from transfer case. Connect ohmmeter between switch terminals.
2. Push pin on end of switch inward and ensure continuity exists. No continuity should exist when switch pin is released (outward) position. Replace switch if defective.

FUEL PUMP ELECTRONIC CONTROL UNIT

See FUEL DELIVERY under FUEL SYSTEM.

CIRCUIT OPENING RELAY

1. Ensure ignition is off. Remove circuit opening relay. See «CIRCUIT OPENING RELAY LOCATION»(ref-21627-S14097534412001010300000) table. NOTE: Circuit opening relay may also be identified using illustration in the «THEORY/OPERATION - 2.7L»(ref-21690) article or wire color. See wiring diagram in the WIRING DIAGRAMS article. CIRCUIT OPENING RELAY LOCATION Application Relay Location T100 Behind Glove Box, Near Passenger's Side Kick Panel
2. Using ohmmeter, check continuity between specified terminals. (Scheme 28)
3. Check circuit opening relay operation by applying battery voltage and ground and checking continuity between specified terminals. (Scheme 29) Replace circuit opening relay if defective.

Scheme 28

Scheme 29

EFI MAIN RELAY

1. Ensure ignition is off. Remove EFI main relay. See «EFI MAIN RELAY LOCATION»(ref-21627-S24530525582001010300000) table. NOTE: The EFI main relay may also be identified using appropriate illustration in «THEORY/OPERATION - 2.7L»(ref-21690) article or wire color. See wiring diagram in the WIRING DIAGRAMS article. EFI MAIN RELAY LOCATION Application Location T100 Fuse/Relay Box Near Driver's Side Front Corner Of Engine Bay
2. Using ohmmeter, check continuity between specified terminals. (Scheme 30)
3. Check EFI main relay operation by applying battery voltage and ground and checking continuity between specified terminals. (Scheme 31) Replace EFI main relay if defective.

Scheme 30

Scheme 31

See CIRCUIT OPENING RELAY under RELAYS.

See EFI MAIN RELAY under RELAYS.

Fuel Pump Pressure

For fuel pump pressure testing, see FUEL PRESSURE in the BASIC TESTING - 2.7L article.

Fuel Injectors

1. Ensure ignition is off. Disconnect electrical connector at fuel injector. Using ohmmeter, measure resistance between fuel injector electrical terminals. Replace fuel injector if resistance is not within specification. See «FUEL INJECTOR RESISTANCE SPECIFICATIONS»(ref-21627-S03149909212001010300000) table.
2. To check fuel injector spray pattern and volume, remove fuel injector. See the REMOVE/INSTALL/OVERHAUL article. Disconnect fuel hose from fuel filter outlet. Use Delivery Hose (09268-41045) to install fuel injector between fuel filter and fuel pressure regulator. (Scheme 32)and (Scheme 33).
3. Place fuel injector into a clean graduated container. Place vinyl tube on end of fuel injector to prevent fuel spillage. NOTE: Scan tester is used to operate the fuel pump or by applying battery voltage to electric fuel pump.
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 the «BASIC TESTING - 2.7L»(ref-21581) article.
5. Connect fuel injector tester to fuel injector for 15 seconds. Use Fuel Injector Tester (09842-30070).
6. Measure fuel injector volume and check spray pattern. Test each fuel injector 2-3 times. Replace fuel injector if volume is not as specified. See the «FUEL INJECTOR VOLUME SPECIFICATIONS»(ref-21627-S04517456892001010300000) table. NOTE: Ensure difference between fuel injector volume on all fuel injectors is within specification. See FUEL INJECTOR VOLUME SPECIFICATIONS table.
7. Disconnect fuel injector tester. Ensure fuel leakage from end of fuel injector is one drop or less in specified time. See the «FUEL INJECTOR LEAKAGE SPECIFICATIONS»(ref-21627-S18513309202001010300000) table. Replace fuel injector if leakage exceeds specified amount.

FUEL INJECTOR RESISTANCE SPECIFICATIONS

FUEL INJECTOR VOLUME SPECIFICATIONS

FUEL INJECTOR LEAKAGE SPECIFICATIONS

Scheme 32

Scheme 33

Note. Fuel pressure control system may also be referred to as fuel pressure-up system.

Fuel Pressure Control System

1. Fuel pressure control system uses a fuel pressure control Vacuum Switching Valve (VSV). Fuel pressure control VSV is supplied voltage through EFI main relay.
2. The Engine Control Module (ECM) will activate VSV by controlling ground circuit for approximately 90-180 seconds when restarting engine at normal operating temperature. Locate and remove fuel pressure control VSV. See «FUEL PRESSURE CONTROL VSV LOCATION»(ref-21627-S22681427302001010300000) table. NOTE: Fuel pressure control VSV may also be identified using illustration in the «THEORY/OPERATION - 2.7L»(ref-21690) article or wire color. See wiring diagram in WIRING DIAGRAMS article. FUEL PRESSURE CONTROL VSV LOCATION Application Location 2.7L Just Below Valve Cover, At Front Of Intake Manifold
3. Using ohmmeter, check resistance and for continuity between fuel pressure control VSV electrical terminals. Replace fuel pressure control VSV if no continuity exists or resistance is not within specification. See «FUEL PRESSURE CONTROL VSV RESISTANCE SPECIFICATIONS»(ref-21627-S03237504282001010300000) table.
4. Ensure no continuity exists between each electrical terminal and fuel pressure control VSV body. Replace fuel pressure control VSV if continuity exists between electrical connector and fuel pressure control VSV body.
5. Check fuel pressure control VSV operation by applying air pressure to designated area and checking air passage, and then applying battery voltage and ground and retesting. (Scheme 34) Replace fuel pressure control VSV if defective.

FUEL PRESSURE CONTROL VSV RESISTANCE SPECIFICATIONS

Scheme 34

Fuel Cut System

1. When checking fuel cut system, engine RPM must be monitored.
2. Scan tester is connected to data link connector No. 3 for monitoring engine RPM. For connecting of scan tester, see appropriate application under IDLE SPEED & MIXTURE in the «ADJUSTMENTS - 2.7L»(ref-21626) article. CAUTION: Some tachometers may not be compatible with ignition system. Consult tachometer manufacturer before connecting tachometer to system. To avoid possible damage to ignitor and/or coil, DO NOT allow tachometer terminal to become grounded.
3. Start and warm engine to normal operating temperature. Ensure all accessories are off. Gradually increase engine RPM to maintain at least specified engine speed. See «FUEL CUT SYSTEM TESTING SPECIFICATION»(ref-21627-S37972971002001010300000) table. FUEL CUT SYSTEM TESTING SPECIFICATION Application Engine RPM 2.7L 3000
4. Using stethoscope, check for fuel injector operating sound. Ensure when throttle lever is released, fuel injector stops operating momentarily (fuel cut RPM) and then resumes operating (fuel return RPM).
5. Ensure fuel cut RPM (if available) and fuel return RPM are within specification. See «FUEL CUT SYSTEM SPECIFICATIONS»(ref-21627-S07347086242001010300000) table. Shut engine off. Remove test equipment.

FUEL CUT SYSTEM SPECIFICATIONS (1)

A/C IDLE-UP VALVE

1. Remove A/C idle-up valve. See «A/C IDLE-UP VALVE LOCATIONS»(ref-21627-S30549464352001010300000) table. NOTE: The A/C idle-up valve may also be identified using illustration in the «THEORY/OPERATION - 2.7L»(ref-21690) article or wire color. See wiring diagram in the WIRING DIAGRAMS article. A/C IDLE-UP VALVE LOCATIONS Application Valve Location 4-Cyl. Passenger's Side Rear Corner Of Engine, Near Air Intake & Contains 2-Pin Black Connector
2. Using ohmmeter, check resistance between A/C idle-up valve electrical terminals. Replace A/C idle-up valve if resistance is within specification. See «A/C IDLE-UP VALVE RESISTANCE SPECIFICATIONS»(ref-21627-S05774945492001010300000) table. A/C IDLE-UP VALVE RESISTANCE SPECIFICATIONS Application Ohms @ 68°F (20°C) T100 30-34
3. Ensure no continuity exists between each electrical terminal and body of A/C idle-up valve. To check A/C idle-up valve operation, apply air pressure to designated area and checking air passage, and then applying battery voltage and ground and retesting. (Scheme 35) Replace A/C idle-up valve if defective.

Scheme 35

IDLE AIR CONTROL (IAC) VALVE

1. Warm engine to normal operating temperature. Ensure idle speed is correct. See IDLE SPEED & MIXTURE in «ADJUSTMENTS - 2.7L»(ref-21626) 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 36) Start engine and note RPM. NOTE: Data link connector No. 1 is located in engine compartment.
3. Engine RPM should increase to specified RPM for 5 seconds, and then return to idle. See «IAC VALVE ENGINE SPEED TESTING SPECIFICATIONS»(ref-21627-S35474605492001010300000) table. IAC VALVE ENGINE SPEED TESTING SPECIFICATIONS Application Engine RPM 2.7L 1000-1500
4. If engine RPM is not as specified, check IAC valve resistance and operation. If engine RPM is within specification, remove jumper wire. Turn ignition off.
5. To check IAC valve resistance, ensure ignition is off. Disconnect electrical connector from IAC valve located on lower area of throttle body. Using ohmmeter, measure resistance between terminal B+ or +B and each remaining terminal. (Scheme 37)
6. Replace IAC valve if resistance is not within specification. See «IAC VALVE RESISTANCE SPECIFICATIONS»(ref-21627-S09210565802001010300000) table.
7. To check IAC valve operation, remove IAC valve from throttle body. Connect battery voltage and ground to proper terminals and ensure valve opens and closes. (Scheme 38) Replace IAC valve if defective.
8. If IAC valve resistance is correct and operates correctly, check wiring circuit between Engine Control Module (ECM) and IAC valve. See «ECM LOCATION»(ref-21627-S40519318942001010300000) table. See wiring diagram in the WIRING DIAGRAMS article.

IAC VALVE RESISTANCE SPECIFICATIONS

Scheme 36

Scheme 37

Scheme 38

IGNITION SYSTEM

Note. For basic ignition checks, see the BASIC TESTING - 2.7L article.

See KNOCK SENSOR under ENGINE SENSORS & SWITCHES.

EGR VACUUM MODULATOR

Note. When testing EGR vacuum modulator, it will be necessary to monitor engine RPM by using tachometer or scan tester depending on model application. For tachometer or scan tester connections, see IDLE SPEED & MIXTURE in the ADJUSTMENTS - 2.7L article.

1. Mark vacuum hose locations and disconnect vacuum hoses from EGR vacuum modulator. Block ports "P" and "R" on EGR vacuum modulator. (Scheme 39) 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". (Scheme 39) Air should pass freely through air filter side of EGR vacuum modulator.
3. Start and operate engine at specified RPM. See «EGR VACUUM MODULATOR TESTING SPECIFICATIONS»(ref-21627-S33293389762001010300000) table. Repeat test procedures in steps 1) and 2). Strong resistance of airflow should be felt. Replace EGR vacuum modulator if resistance is not felt. Reconnect vacuum hoses to proper locations.

Scheme 39

EGR VACUUM MODULATOR TESTING SPECIFICATIONS

A/T

1. Remove EGR check valve. see scheme 25 Apply air pressure on Orange end of EGR check valve. Air should flow through the EGR check valve.
2. Apply air pressure on Black end of EGR check valve. Air should not flow through the EGR check valve. Replace EGR check valve if defective.

EGR VACUUM SWITCHING VALVE (VSV)

Note. When testing EGR VSV, use proper illustration to determine component location. see scheme 23

1. Disconnect electrical connector from EGR VSV. Using ohmmeter, check resistance between EGR VSV electrical terminals.
2. Replace EGR VSV if resistance is not within specification. See «EGR VSV RESISTANCE SPECIFICATIONS»(ref-21627-S19621533422001010300000) table. Check that no continuity exists between each electrical terminal and EGR VSV body. Replace EGR VSV if continuity exists between any electrical terminal and VSV body.
3. Apply air pressure to port "E" without battery connected. (Scheme 40) Air pressure should not flow through port "F". Connect battery voltage and ground to EGR VSV electrical terminals. (Scheme 40) Apply air pressure to port "E". Air pressure should flow from port "F". Replace EGR VSV if defective.

EGR VSV RESISTANCE SPECIFICATIONS

Scheme 40

FUEL EVAPORATION SYSTEM

Note. Fuel evaporation systems contain different components depending on application. see scheme 23 When testing fuel evaporation system components, use proper illustration to determine component location.

Charcoal Canister

1. Disconnect hoses from charcoal canister. Check for clogged filter and/or stuck check valve by applying low air pressure to port "A". (Scheme 41) Ensure air flows freely from other ports on charcoal canister.
2. Apply low air pressure to port "B". (Scheme 41) Ensure no air flows from port "A", but air flows freely from port "C". 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. Ensure no activated carbon comes out of charcoal canister. DO NOT attempt to wash out charcoal canister.

Scheme 41

EVAP Vacuum Switching Valve

1. Remove EVAP Vacuum Switching Valve (VSV). See «EVAP VSV LOCATIONS»(ref-21627-S02138995002001010300000) table. see scheme 23 EVAP VSV LOCATIONS Application Location T100 Near Charcoal Canister NOTE: EVAP VSV may also be identified by wire colors. See wiring diagram in the WIRING DIAGRAMS article.
2. Using ohmmeter, ensure continuity exists between electrical terminals on EVAP VSV and resistance is within specification. See «EVAP VSV RESISTANCE SPECIFICATIONS»(ref-21627-S24392386552001010300000) table. EVAP VSV RESISTANCE SPECIFICATIONS Application Ohms @ 68°F (20°C) 2.7L 30-34
3. Ensure no continuity exists between each electrical terminal and the body of the EVAP VSV. Apply air pressure to port "E". Ensure no air passes out port "F". Perform STEP 1. (Scheme 42)
4. Connect battery voltage and ground to EVAP VSV electrical terminals. Apply air pressure to port "E". Ensure air passes out port "F". Perform STEP 2. (Scheme 43) Replace EVAP VSV if defective.

Scheme 42

Scheme 43

POSITIVE CRANKCASE VENTILATION (PCV)

1. Remove PCV valve. Attach hose to PCV valve. Blow air from cylinder head side of PCV valve. Ensure air passes easily through PCV valve.
2. Blow air from intake manifold side of PCV valve. Ensure air passes through PCV valve with some restriction. Replace PCV valve if valve does not function as described.

THROTTLE OPENER

1. Warm engine to normal operating temperature. Ensure idle speed is correct. See IDLE SPEED & MIXTURE in «ADJUSTMENTS - 2.7L»(ref-21626) article.
2. Disconnect/plug vacuum hose at throttle opener, located on side of throttle body. Start engine and note engine speed. Engine speed should be within specs. See «THROTTLE OPENER SPECIFICATIONS»(ref-21627-S21590789842001010300000) table.
3. If engine speed is not within specification, replace throttle body. Shut engine off. Reinstall vacuum hose on throttle opener. Start engine and ensure engine returns to proper idle speed.

THROTTLE OPENER SPECIFICATIONS