Engine Controls - System/component Tests: Other Lexus LX J80

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

AIRFLOW METER

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

1. Turn ignition off. Disconnect electrical connector from airflow meter. Note airflow meter terminal identification. (Scheme 22)
2. Using ohmmeter, check resistance between terminal E2 and THA. Resistance should be within specification in relation to the temperature. See «AIRFLOW METER RESISTANCE SPECIFICATIONS»(ref-21992-S16958410362001010300000) table. Replace airflow meter if resistance is not within specification.
3. To check airflow meter operation, ensure electrical connector is installed on airflow meter. Connect voltmeter leads to proper terminals on airflow meter with electrical connector installed. (Scheme 23)
4. Turn ignition on. Apply air into airflow meter and note voltage reading. (Scheme 23) While air is being applied, voltage reading should fluctuate. Replace airflow meter if voltage does not fluctuate. Turn ignition off. Remove voltmeter.

AIRFLOW METER RESISTANCE SPECIFICATIONS

Scheme 22

Scheme 23

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 in BASIC TESTING article.

CRANKSHAFT POSITION SENSOR

For testing crankshaft position sensor, see CRANKSHAFT POSITION SENSOR under IGNITION CHECKS in BASIC TESTING article.

EGR GAS TEMPERATURE SENSOR

1. Remove EGR gas temperature sensor from side of EGR valve. Place threaded end of EGR gas temperature sensor and thermometer in container of oil.
2. Attach ohmmeter between electrical terminals on EGR gas temperature sensor. Heat oil and note resistance at specified temperature. See «EGR GAS TEMPERATURE SENSOR SPECIFICATIONS»(ref-21992-S27371619552001010300000) table. Replace EGR gas temperature sensor if resistance is not within specification. Reinstall EGR gas temperature sensor and tighten to 15 ft. lbs. (20 N.m).

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-21992-S26455110012001010300000) 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-21908) article.
2. Using ohmmeter, check resistance between electrical terminals on ECT sensor. Resistance should be within specification at designated temperature. (Scheme 24) Replace ECT sensor if resistance is not within specification.

ENGINE COOLANT TEMPERATURE (ECT) SENSOR LOCATION

Scheme 24

KNOCK SENSOR

1. Knock sensor(s) are located on driver's side of the cylinder block, just below cylinder head. (Scheme 25) 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 25

HEATED OXYGEN SENSOR

1. Two heated oxygen sensors are used. A heated oxygen sensor is used on exhaust pipe in front of front catalytic converter and on exhaust pipe behind rear catalytic converter.
2. If problem exists with heated oxygen sensor, a diagnostic trouble code will be stored in Engine Control Module (ECM). For diagnostic trouble code diagnosis, see «TESTS W/CODES»(ref-21947) article.
3. To test the heater on the heated oxygen sensor, disconnect electrical connector from appropriate heated oxygen sensor and note heated oxygen sensor terminals. (Scheme 26)
4. Using ohmmeter, check resistance between heated oxygen sensor terminals +B and HT. (Scheme 26) Replace heated oxygen sensor if resistance is not 11-16 ohms at 68°F (20°C).

Scheme 26

PARK/NEUTRAL POSITION SWITCH CIRCUIT

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). See TESTS W/CODES article for accessing diagnostic trouble codes.

PARK/NEUTRAL POSITION (PNP) SWITCH

1. Disconnect electrical connector from Park/Neutral Position (PNP) switch, mounted on side of transmission. Note terminal identification. (Scheme 27)
2. Using ohmmeter, check for continuity between specified terminals with shift lever in proper positions. See «PARK/NEUTRAL POSITION SWITCH SPECIFICATIONS»(ref-21992-S14041983432001010300000) table. If proper continuity cannot obtained, adjust or replace switch as necessary.

PARK/NEUTRAL POSITION SWITCH SPECIFICATIONS

Scheme 27

PICK-UP COILS

See PICK-UP COIL AIR GAP and PICK-UP COIL RESISTANCE under IGNITION CHECKS in BASIC TESTING article.

THROTTLE POSITION SENSOR

1. Ensure ignition is off. Disconnect electrical connector from Throttle Position (TP) sensor located on throttle body. Note terminal identification. (Scheme 28)
2. Apply vacuum to throttle opener. Insert specified thickness feeler gauge between throttle stop screw and throttle lever, and check resistance or continuity. See «THROTTLE POSITION SENSOR RESISTANCE SPECIFICATIONS»(ref-21992-S07827145472001010300000) table. Replace or adjust TP sensor if not within specification.

THROTTLE POSITION SENSOR RESISTANCE SPECIFICATIONS

Scheme 28

VEHICLE SPEED SENSOR

1. Vehicle speed sensor is located on transmission and contains a 3-pin electrical connector. Connect voltmeter and battery voltage to vehicle speed sensor terminals. (Scheme 29)
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.

Scheme 29

CIRCUIT OPENING RELAY

1. Turn ignition off. Remove circuit opening relay from relay box behind driver's side kick panel. (Scheme 30)
2. To test circuit opening relay continuity, use ohmmeter to check continuity between specified terminals. (Scheme 31)
3. To test circuit opening relay operation, apply battery voltage and ground to relay and use ohmmeter to check continuity between specified terminals. (Scheme 32) Replace circuit opening relay if defective.

Scheme 30

Scheme 31

Scheme 32

FUEL PUMP RELAY

1. Ensure ignition is off. Remove fuel pump relay. Fuel pump relay is bolted to fender on driver's side of engine compartment, just above fenderwell and contains a Black 4-pin electrical connector. NOTE: Fuel pump relay may be identified using appropriate illustration in «THEORY/OPERATION»(ref-21908) article.
2. To test fuel pump relay continuity, use ohmmeter to check continuity between specified terminals. (Scheme 33)
3. To test fuel pump relay operation, apply battery voltage and ground to relay and use ohmmeter to check continuity between specified terminals. (Scheme 34) Replace fuel pump relay if defective.

Scheme 33

Scheme 34

See CIRCUIT OPENING RELAY under RELAYS.

Fuel Pump Pressure

For fuel pump pressure testing, see BASIC TESTING article.

See FUEL PUMP RELAY under RELAYS.

Fuel Pump Resistor

1. Ensure ignition is off. Disconnect electrical connector at fuel pump resistor, located on passenger's side of engine compartment, near fenderwell and cruise control actuator. (Scheme 35) Fuel pump resistor contains a Dark Gray 2-pin electrical connector.
2. Using ohmmeter, check resistance between terminals on electrical connector for fuel pump resistor. Replace fuel pump resistor if resistance is not.70-.76 ohms at 68°F (20°C).

Scheme 35

FUEL CONTROL

Note. Solenoid resistor may also be referred to as fuel injector resistor or SFI resistor.

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-21992-S31886493662001010300000) 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 36)
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 under FUEL SYSTEM in «BASIC TESTING»(ref-21926) article.
5. Connect Fuel Injector Tester (09842-30070) to fuel injector for 15 seconds. (Scheme 37) 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-21992-S38903516862001010300000) 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 per minute. Replace fuel injector if leakage exceeds specification. Remove test equipment.

FUEL INJECTOR RESISTANCE SPECIFICATIONS

FUEL INJECTOR VOLUME SPECIFICATIONS

Scheme 36

Scheme 37

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-21992-S12932601382001010300000) table. NOTE: Fuel pressure control VSV may also be identified using appropriate illustration in «THEORY/OPERATION»(ref-21908) article and by wire color. See appropriate wiring diagram in WIRING DIAGRAMS article. FUEL PRESSURE CONTROL VSV LOCATION Application Location Land Cruiser (1) Front Lower Side Of Air Intake Chamber, Near Dipstick (1) Contains Brown 2-pin electrical connector.
3. Using ohmmeter, ensure continuity exists between electrical terminals on fuel pressure control VSV and resistance is within specification. See «FUEL PRESSURE CONTROL VSV RESISTANCE SPECIFICATIONS»(ref-21992-S41304196972001010300000) table. Replace fuel pressure control VSV if no continuity exists or resistance is not within specification.
4. Ensure no continuity exists between each electrical terminal and body of fuel pressure control VSV. Replace fuel pressure control VSV if continuity exists between electrical terminal and body of fuel pressure control VSV.
5. Check fuel pressure control VSV operation by applying air pressure to designated area and check that air flows from the end of the fuel pressure control VSV without battery connected. (Scheme 38)
6. Apply battery voltage and ground to electrical terminals on fuel pressure control VSV and reapply air pressure. Air pressure should now pass from the filter. (Scheme 38) Replace fuel pressure control VSV if defective.

FUEL PRESSURE CONTROL VSV RESISTANCE SPECIFICATIONS

Scheme 38

Fuel Cut System

1. When checking fuel cut system, engine RPM must be monitored. Scan tester is connected to data link connector No. 3 for monitoring engine RPM. For connecting of scan tester, see IDLE SPEED & MIXTURE in «ADJUSTMENTS»(ref-21890) article.
2. Start and warm engine to normal operating temperature. Ensure A/C and all accessories are off. Gradually increase engine RPM to maintain at least specified engine speed. See «FUEL CUT SYSTEM TESTING SPECIFICATION»(ref-21992-S42876391562001010300000) table. FUEL CUT SYSTEM TESTING SPECIFICATION Application Engine RPM Land Cruiser, LX450 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 SYSTEM SPECIFICATIONS»(ref-21992-S42078680502001010300000) table. Shut engine off. Remove test equipment.

FUEL CUT SYSTEM SPECIFICATIONS (1)

IDLE AIR CONTROL (IAC) VALVE

Note. IAC valve is located on side of throttle body, near throttle position sensor.

1. Listen for clicking sound at IAC valve immediately after engine is shut off. If no clicking sound is heard, check IAC valve resistance and operation.
2. To test IAC valve resistance, ensure ignition is off. Disconnect electrical connector from IAC valve. Using ohmmeter, check resistance between specified terminals. See «IAC VALVE RESISTANCE SPECIFICATIONS»(ref-21992-S22793348862001010300000) table. (Scheme 39) Replace IAC valve if resistance is not within specification. IAC VALVE RESISTANCE SPECIFICATIONS Terminals Ohms B1 To S1 Or S3 Cold (1) 15-25 Hot (2) 20-30 B2 To S2 Or S4 Cold (1) 15-25 Hot (2) 20-30 (1) Cold is with temperature of 14-122°F (-10-50°C). (2) Hot is with temperature of 122-212°F (50-100°C).
3. To test IAC valve operation, remove IAC valve. Apply battery voltage to terminals B1 and B2. (Scheme 39) Repeatedly ground terminals in sequence, and ensure IAC valve closes and opens. See «IAC VALVE GROUNDING SEQUENCE»(ref-21992-S12128920442001010300000) table. (Scheme 33) Replace IAC valve if defective. IAC VALVE GROUNDING SEQUENCE Application Terminal Grounding Sequence To Close IAC Valve S1-S2-S3-S4-S1 To Open IAC Valve S4-S3-S2-S1-S4
4. If IAC valve resistance is within specification and IAC valve operates correctly, check wiring between Engine Control Module (ECM) and IAC valve. See appropriate wiring diagram in WIRING DIAGRAMS article.
5. ECM is located above glove box.

Scheme 39

Scheme 40

Scheme 41

IGNITION SYSTEM

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

See KNOCK SENSOR under ENGINE SENSORS & SWITCHES .

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 tachometer or scan tester depending on model application. For tachometer or scan tester connections, see IDLE SPEED & MIXTURE in ADJUSTMENTS article.

1. Mark vacuum hose locations and disconnect vacuum hoses from EGR vacuum modulator. Block ports "P" and "R" on EGR vacuum modulator. see scheme 23 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 23 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-21992-S29778097092001010300000) 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.

EGR VACUUM MODULATOR TESTING SPECIFICATIONS

EGR VACUUM SWITCHING VALVE (VSV)

1. Disconnect vacuum hoses and electrical connector from EGR VSV, located below air intake chamber. (Scheme 34) It may be necessary to remove air intake chamber to access EGR VSV.
2. Using ohmmeter, check that continuity exists between electrical terminals on EGR VSV and that resistance is within specification. See «EGR VSV RESISTANCE SPECIFICATIONS»(ref-21992-S16736306112001010300000) table. Replace EGR VSV if no continuity exists or resistance is not within specification.
3. Ensure no continuity exists between each electrical terminal and body of the EGR VSV. Replace EGR VSV if continuity exists between any electrical terminal and body of EGR VSV.
4. Apply air pressure to port "G" without battery connected. (Scheme 42) Air pressure should flow through port "E". Apply battery voltage and ground to electrical terminals on EGR VSV. (Scheme 42) Apply air pressure to port "G". Air pressure should not flow from port "E". Replace EGR VSV if defective.

EGR VSV RESISTANCE SPECIFICATIONS

Scheme 42

EVAP Thermal Vacuum Valve

1. Drain cooling system. Remove EVAP TVV located in coolant passage on cylinder head. (Scheme 34)
2. Use cool water to cool threaded end of EVAP TVV to less than 113°F (45°C). Apply air pressure to lower vacuum hose port on EVAP TVV. Ensure EVAP TVV is closed and air flows from the air filter, located on top of EVAP TVV.
3. Heat water to greater than 147°F (64°C). Apply air pressure to lower vacuum hose port on EVAP TVV. Ensure EVAP TVV is open and air flows through upper vacuum hose port and not through air filter. Replace EVAP TVV if defective. Apply thread sealant to threads of EVAP TVV and reinstall. Tighten EVAP TVV to 21 ft. lbs. (29 N.m). Fill cooling system.

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 35) Ensure air flows freely from other ports on charcoal canister.
2. Apply low air pressure to port "B" while holding port "C" closed. (Scheme 35) Ensure air flows freely from port "A". 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 port "C". Ensure no activated carbon comes out of charcoal canister. DO NOT attempt to wash out charcoal canister.

Scheme 43

EVAP Check Valve

1. Remove EVAP check valve from vacuum hose to EVAP Vacuum Control Valve (VCV). The EVAP VCV is located on bracket, below air intake chamber, near engine oil dipstick. (Scheme 34)
2. Apply air pressure to Orange colored side of EVAP check valve. Air should flow through EVAP check valve. Apply air pressure to Black colored side of EVAP check valve. Air should not flow through EVAP check valve. Replace EVAP check valve if defective. The EVAP check valve should be installed with Black colored side toward the VCV.

EVAP Vacuum Control Valve

1. Warm engine to normal operating temperature. Disconnect vacuum hose from union pipe at EVAP Vacuum Control Valve (VCV). (Scheme 44) With engine idling, ensure no suction exists on union pipe at EVAP Vacuum Control Valve (VCV).
2. Gradually increase engine to 3000 RPM. Ensure suction now exists on union pipe. If suction does not exist, remove EVAP VCV. Using vacuum pump, apply 2.8 in. Hg of vacuum to port "S" on EVAP VCV. (Scheme 44)
3. Apply air pressure to port "Y". Ensure air flows from port "Z". Remove vacuum pump. Apply air pressure to port "Y". Ensure air does not flow from port "Z". Replace EVAP VCV if defective and recheck operation. If EVAP VCV is okay, check EVAP Vacuum Switching Valve (VSV).

Scheme 44

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.

DASHPOT CONTROL SYSTEM

1. Warm engine to normal operating temperature. Ensure idle speed is within specification. See IDLE SPEED & MIXTURE in the «ADJUSTMENTS»(ref-21890) article.
2. With engine idling, open throttle valve on throttle body until throttle lever separates from end of dashpot. Gradually release throttle valve and note dashpot setting RPM when throttle lever contacts dashpot.
3. Dashpot setting RPM should be 1900-2500 RPM. If dashpot setting RPM is not within specification, shut engine off. Loosen lock nut and rotate stopper bolt. (Scheme 45)
4. Repeat step 2) until proper adjustment is obtained. Tighten lock nut. To check throttle body Vacuum Transmitting Valve (VTV) operation, operate engine at 3500 RPM. Release throttle. Ensure engine returns to proper idle speed in a few seconds.

Scheme 45

THROTTLE OPENER

1. Warm engine to normal operating temperature. Ensure idle speed is within specification. See IDLE SPEED & MIXTURE in the «ADJUSTMENTS»(ref-21890) article.
2. Disconnect and plug vacuum hose at throttle opener, located on side of throttle body. Start engine and note engine speed. Engine speed should be 700-1000 RPM.
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.