Engine Controls - System/component Tests Toyota Land Cruiser 80

INTRODUCTION

Before testing separate components or systems, perform procedures in BASIC TESTING article in the ENGINE PERFORMANCE Section. Since many computer-controlled and monitored components set a trouble code if they malfunction, also perform procedures in TESTS W/CODES article in the ENGINE PERFORMANCE Section.

Note. Testing individual components does not isolate shorts or opens. Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure. Use ohmmeter to isolate wiring harness shorts or opens.

AIRFLOW METER

Turn ignition off. Unplug wiring connector from air- flow meter. Note terminal identification. (Scheme 61) Use ohmmeter to measure resistance between specified terminals. See AIRFLOW METER RESISTANCE SPECIFICATIONS table. Replace airflow meter if not within specification.

Scheme 60

Scheme 61

AIRFLOW METER RESISTANCE SPECIFICATIONS

COLD START INJECTOR TIME SWITCH

Turn ignition off. Remove connector from switch. (Scheme 62)for Time Switch Location. Measure resistance across switch terminals at specified temperature. (Scheme 63) Replace switch if resistance is not within specification. See COLD START INJECTOR TIME SWITCH RESISTANCE SPECIFICATIONS table.

COLD START INJECTOR TIME SWITCH RESISTANCE SPECIFICATIONS

Scheme 62

Scheme 63

COOLANT TEMPERATURE SENSOR

1. Ensure ignition is off. Unplug connector from sensor. For sensor location (Scheme 62)
2. Using ohmmeter, check resistance between sensor terminals. Replace sensor if resistance is not within specification at specified temperature. (Scheme 64)

Scheme 64

EGR GAS TEMPERATURE SENSOR

1. Remove sensor from side of EGR valve. Place threaded end of sensor and thermometer in container of oil. (Scheme 65)
2. Attach ohmmeter to sensor terminals. Heat oil and note resistance at specified temperature. See «EGR TEMPERATURE SENSOR SPECIFICATIONS»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table. Replace sensor if not within specification.

EGR TEMPERATURE SENSOR SPECIFICATIONS

Scheme 65

KNOCK SENSOR

Probable causes of knock sensor problems include the following

1. Open or short in knock sensor circuit.
2. Knock sensor (looseness etc.).
3. Knock control in ECU is faulty.

Knock sensor problems can also set fault codes 52 and 53. For code charts, see TESTS W/CODES article in the ENGINE PERFORMANCE Section.

NEUTRAL/START SWITCH

Unplug switch connector at transmission or transaxle. Note terminal identification. (Scheme 66) Using ohmmeter, check for continuity at specified terminals with gearshift in correct range. See NEUTRAL/START SWITCH SPECIFICATIONS table.

NEUTRAL/START SWITCH SPECIFICATIONS

Scheme 66

OXYGEN (O2) SENSOR FEEDBACK VOLTAGE TEST

1. Warm engine to normal operating temperature. Connect analog-type voltmeter to engine check connector VF1 (or VF) and E1 terminals. (Scheme 67) Perform procedures listed in (Scheme 68).
2. Vehicle is equipped with a main O2 sensor and an O2 sensor heater.

Note. Codes No. 21, 25, 26 and 27 are O2 sensor circuit codes. Also check for coolant temperature sensor Code No. 22. Faulty coolant temperature sensor could cause faulty O2 sensor readings.

Scheme 67

Scheme 68

OXYGEN (O2) SENSOR HEATER

1. Unplug O2 sensor connector. Using ohmmeter, measure resistance between sensor terminals. +B and HT. (Scheme 69) Replace sensor if resistance is not 5.1-6.3 ohms.
2. A Code No. 21 is also an indicator of a problem in O2 sensor circuit. Code No. 21 will set if O2 sensor heater circuit opens or shorts to ground on HT wire from sensor to ECU.

Scheme 69

PICK-UP COILS

See PICK-UP AIR GAP and PICK-UP COIL RESISTANCE in BASIC TESTING article in the ENGINE PERFORMANCE Section.

THROTTLE POSITION SENSOR (TPS)

Turn ignition off. Unplug electrical connector at TPS on throttle body. Note terminal identification. (Scheme 70) Insert specified thickness feeler gauge between throttle stop screw and throttle lever. See TPS RESISTANCE SPECIFICATIONS table. Using an ohmmeter, check for resistance or continuity. Replace or adjust TPS if not within specification.

TPS RESISTANCE SPECIFICATIONS

Scheme 70

VEHICLE SPEED SENSOR

1. Apply positive battery voltage to terminal No. 1 of speed sensor. (Scheme 71) Connect terminal No. 3 to ground. Connect ohmmeter between terminal No. 2 and negative terminal of battery
2. Ohmmeter should show continuity as meter shaft is rotated (4 times per revolution). If ohmmeter does not deflect as specified, replace speed sensor.

Scheme 71

4WD SWITCH

Switch is located on right side of transfer case. Remove switch from transfer case. With ohmmeter connected between switch terminal and switch body, there should be continuity when the switch pin is pushed inward.

CIRCUIT OPENING RELAY

Circuit opening relay is located behind center of dash. To check circuit opening relay (Scheme 72)and (Scheme 73). Replace relay if continuity is not as specified.

Note. During cranking, there should be 12 volts present at FP terminal of circuit opening relay. This is the fuel pump (or fuel pump relay) line. See WIRING DIAGRAMS article in the ENGINE PERFORMANCE Section for wire color.

Scheme 72

Scheme 73

EFI MAIN RELAY

EFI main relay is on right front fenderwell. To test EFI main relay (Scheme 74) Replace relay if defective.

Scheme 74

FUEL PUMP RELAY

See FUEL DELIVERY under FUEL SYSTEM for testing.

FUEL SYSTEM

Fuel Pressure Release

Disconnect negative battery terminal. Place container under fitting to be loosened. Use a rag to cover fuel line/component. Slowly loosen fitting, allowing pressurized fuel to spill into container. After fuel system has depressurized, disconnect and plug fitting.

FUEL DELIVERY

For fuel pump pressure and fuel pressure regulator testing, see BASIC TESTING article in the ENGINE PERFORMANCE Section.

Fuel Injectors

1. Turn ignition off. Unplug each injector connector. Measure resistance across both terminals. If resistance is not 13.8 ohms at 68°F (20°C), replace fuel injector.
2. To check injector spray pattern and volume, relieve fuel system pressure. Remove injectors from engine. Disconnect fuel hose from fuel filter outlet. Use Fuel Pressure Gauge (09268-41045) to "T" fuel injector between fuel filter and fuel pressure regulator. (Scheme 75)and (Scheme 76).
3. Place injector into clean container. Place tube on end of injector to prevent fuel from spilling. Connect Fuel Injector Tester (09842-30070) or trigger box with appropriate resistor to fuel injector. Turn ignition on, with engine off.
4. Connect jumper wire to engine check connector terminals FP and +B to pressurize fuel system. For engine check connector locations (Scheme 67) Connector terminals are marked on inside of check connector cover.
5. Trigger injector for 15 seconds. Measure volume and check spray pattern. Test each injector 2-3 times. Replace injector if volume is not 2.9-3.6 cu. in. (47-59 cc). Maximum difference between each injector is.3 cu. in. (5 cc).
6. Disconnect injector trigger. Fuel leakage from end of injector should be one drop or less in one minute. Replace injector if leakage is more than specified.

Scheme 75

Scheme 76

Fuel Pressure-Up System

1. Ensure coolant temperature switch is operating correctly. Switch is in side of engine block and has a Pink wire attached. There should be no continuity between switch terminal and body when coolant temperature is less than 208°F (98°C). There should be continuity between switch terminal and body when coolant temperature is more than 220°F (105°C). NOTE: The ECU uses signal from coolant temperature switch to control the ground circuit for fuel pressure-up vacuum switching valve.
2. Fuel pressure-up system is controlled by ECU through a vacuum switching valve. The vacuum switching valve is fed current through the EFI main relay when the ignition is turned on. ECU controls the ground circuit. ECU will activate vacuum switching valve for 90-180 seconds when restarting engine at normal operating temperature.
3. Vacuum switching valve is located on left fender (rear most vacuum switching valve). Check operation of vacuum switching valve using (Scheme 77) as a reference.

Scheme 77

Deceleration Fuel-Cut System

1. Connect a tachometer to engine (to monitor needle fluctuations). See ADJUSTMENTS article in the ENGINE PERFORMANCE Section for tachometer attaching points. Start engine and warm to operating temperature. Ensure A/C and other accessories are off.
2. Unplug throttle position sensor connector from throttle position sensor. Short terminals IDL and E1 (or E2) on wire side of connector. (Scheme 70)for terminal identification.
3. Gradually raise engine RPM. Fuel-cut operation can be checked by noting the fluctuation of tachometer needle. Fluctuation indicates fuel-cut system is being turned on and off. (Scheme 78) Check that fuel-cut points and fuel return points are within specifications. See «DECELERATION FUEL-CUT & FUEL RETURN RPM»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table.

DECELERATION FUEL-CUT & FUEL RETURN RPM

Scheme 78

Cold Start Injector

1. Disconnect negative battery cable. Disconnect cold start injector wiring harness connector. Check resistance between terminals of injector. Replace injector if resistance is not 2-4 ohms. If resistance is okay, relieve fuel system pressure.
2. Remove cold start injector from vehicle. Install fuel hose to injector. Install system Union Adapters (9268-41045) to delivery pipe and cold start injector. Connect fuel hose to union adapters. (Scheme 79) Connect Jumper Harness (9842-30050) to cold start injector.
3. Place container under cold start injector. Connect jumper wire to engine check connector terminals FP and B+ to pressurize fuel system. For engine check connector locations (Scheme 67) Turn ignition on, with engine off. CAUTION: Perform cold start injector connector test in shortest possible time.
4. Connect probes of Fuel Injection Tester (09842-30070) to battery. Connect other end of tester to cold start injector. (Scheme 79) Ensure fuel spray is an even cone shape.
5. Disconnect fuel injector tester harness and observe cold start injector. Maximum leakage should be one drop per minute with fuel pressure applied. Clean or replace cold start injector if defective.

Scheme 79

Note. Cold start injector is controlled by cold start injector time switch when ignition switch is turned on.

For test procedures, see ENGINE SENSORS & SWITCHES.

IDLE SPEED CONTROL (ISC) SYSTEM

1. Listen for clicking sound after engine is shut off. If no sound is heard, check ISC valve and wiring.
2. To check wiring circuit, turn engine off. Unplug ISC valve connector. Turn ignition on with engine off. Connect voltmeter between B1 and B2 terminals of wiring harness connector. (Scheme 80) Battery voltage should be present. If not, check wiring between ISC valve and EFI main relay.
3. To check ISC valve, turn ignition off. Unplug ISC valve connector. Measure resistance between ISC valve terminals. (Scheme 80) See «ISC VALVE RESISTANCE SPECIFICATIONS»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table. Replace ISC valve if resistance is not as specified. ISC VALVE RESISTANCE SPECIFICATIONS Terminals Ohms B1 to S1 or S3 10-30 B2 to S2 or S 10-30 NOTE: Before removing ISC valve, drain coolant from cooling system. Remove both coolant by-pass hoses. On Supra Turbo only, ensure check valve and seal washer are installed in air intake chamber.
4. To check valve operation, remove ISC valve from vehicle. Apply battery voltage to terminal B1 and terminal B2. (Scheme 80) Repeatedly ground terminals S1, S2, S3 and S in sequence. Valve should close. Remove ground wires.
5. Apply battery voltage to terminals B1 and B2. Repeatedly ground terminals S, S3, S2 and S1 in sequence. Valve should move toward open position. Replace valve if operation is not as specified.

Scheme 80

IGNITION SYSTEM

Note. For basic ignition checks, see BASIC TESTING article in the ENGINE PERFORMANCE Section.

Probable causes of knock sensor problems include the following

1. Open or short in knock sensor circuit.
2. Knock sensor (looseness etc.).
3. Knock control in ECU is faulty.

Knock sensor problems can also set fault codes 52 and 53. For code charts, see TESTS W/CODES article in the ENGINE PERFORMANCE Section.

System Test

1. Inspect air pump belt. Visually check hoses and tubes for kinks, damage or loose connections. Disconnect air by-pass hose from Air Switching Valve (ASV). (Scheme 81)
2. With coolant temperature less than 50°F (10°C), start engine and allow to idle. Air should discharge from ASV. When coolant temperature is between 59°F (15°C) and 95°F (35°C), air should stop discharging from ASV.
3. When air stops discharging from ASV, increase engine speed to 3000 RPM. Air should again start discharging from ASV.

Air Pump

1. Disconnect hose at air pump outlet. Attach Air Pump Tester (09258-14010) with.217" (5.51 mm) orifice to hose. (Scheme 81)
2. Start engine and increase engine speed to 1200 RPM. Tester gauge should read in Green area. If reading is in Red area, replace air pump assembly.

Scheme 81

Air Switching Valve (ASV)

1. With engine operating at idle speed, disconnect vacuum hose from ASV. ASV is on left side fenderwell (front valve). Air should discharge from ASV. Reconnect vacuum hose.
2. Check opening pressure of ASV relief valve. Disconnect air hose from check valve "A". Connect Air Pump Tester (09258-14010) to air hose. Disconnect vacuum hose from ASV and connect to vapor filter. (Scheme 81)
3. Block orifice on air pump tester with finger. Increase engine speed gradually and measure relief valve opening pressure. Opening pressure should be 5.7-8.5 psi (.40-.60 kg/cm 2 ). Remove air pump tester. Reconnect vacuum hoses.

Vacuum Switching Valve (VSV)

1. Locate VSV on left side fenderwell (front valve). Blow air into nozzle "E". Air should come out of nozzle "P". (Scheme 82)
2. Apply battery voltage to VSV terminals. Blow air into nozzle "E". Air should come out of nozzle "F". If valve does not function as described, replace VSV.

Check Valves

1. Inspect check valve "A" by blowing air from each side of valve. (Scheme 83) Ensure air does not flow from manifold side of valve to Air Switching Valve (ASV) side.
2. Air should flow from Air Switching Valve ASV to manifold. If check valve does not function as described, replace valve.
3. Inspect check valve "B". Ensure air does not flow from Black to Orange side of nozzle. Air should flow from Orange to Black side. If check valve does not function as described, replace valve.

Scheme 82

Scheme 83

1. Ensure modulator filter is clean and in good condition prior to performing test. Clean filter with compressed air. Disconnect vacuum hose from EGR valve.
2. Using a "T" connector, connect a vacuum gauge in EGR valve vacuum line. Ensure engine starts and runs smoothly at idle. This ensures proper seating of EGR valve.
3. The Vacuum Switching Valve (VSV) and EGR modulator can be checked with engine coolant temperature less than minimum temperature and specified engine RPM in accordance with application. See «EGR SPECIFICATIONS»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table.
4. Operate engine with engine coolant temperature less than minimum temperature and specified RPM. No vacuum reading should be obtained when operated with engine coolant temperature less than minimum temperature.
5. Operate engine at normal operating temperature and specified RPM. See «EGR SPECIFICATIONS»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table. A low vacuum reading should be obtained.
6. Disconnect hose from the "R" port of EGR vacuum modulator. (Scheme 84)
7. Using additional hose, connect "R" port directly to intake manifold. High vacuum reading should be obtained at specified engine RPM. See «EGR SPECIFICATIONS»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-systemcomponent-tests) table. NOTE: Engine should misfire due to large amounts of exhaust gas being injected into intake manifold.
8. To check EGR valve, apply vacuum directly to EGR valve with engine idling. Engine should run rough or stall. If system did not operate as described, each component should be tested.

EGR SPECIFICATIONS

EGR Vacuum Modulator

1. Disconnect all hoses. Block ports "P" and "R". Apply air pressure to port "Q". (Scheme 84) Air should pass through the air filter side of modulator freely.
2. Operate engine at 2500 RPM. Repeat test procedures in step 1). Strong resistance of airflow should be felt. Replace EGR vacuum modulator if resistance is not felt. Reconnect vacuum hoses to proper locations

Scheme 84

1. Disconnect VSV connector. (Scheme 85) Apply air pressure to port "E". (Scheme 86) Air should pass through port "F".
2. Connect battery to VSV terminals. Apply air pressure to port "E". No air should pass through port "F".

Scheme 85

Scheme 86

FUEL EVAPORATION

Note. (Scheme 87)to identify evaporative emission control systems and operating parameters.

Fuel Odor Or Gas Leaks

Check for disconnected or cracked fuel vapor line or defective components in system. Check all lines and fittings. Check operation of system.

Fuel Tank Or Expansion Tank Deformed

Check for clogged canister, defective vacuum relief filler cap or restricted hoses.

Rough Engine Operation

Check vacuum hose between vacuum solenoid valve (if equipped) and intake manifold for damage or loose connections. Check for malfunctions in all valves. Ensure all vacuum hoses are tight and in good condition.

Bimetallic Vacuum Switching Valve (BVSV)

1. Drain engine coolant. Remove BVSV. Connect hose to top port. Place valve in water that is less than 95°F (35°C). Blow air into hose. Ensure valve is closed.
2. Heat water to 129°F (54°C). Blow air into hose. Ensure valve is open. If valve is not open, replace valve. Apply liquid sealer to threads of valve before installing. Fill cooling system. If BVSV does not operate as described, replace valve.

Charcoal Canister

1. Check for clogged filter and/or stuck check valve by blowing low pressure compressed air into canister tank port. Ensure air flows freely out of other canister ports.
2. Blow air into canister purge port. Ensure air does not flow out of any other port.

Maintenance

1. Inspect fuel tank, canister, vacuum relief filler cap, lines and hoses for damage, leaks and deterioration every 60,000 miles or every 6 years. Replace gasket in vacuum relief filler cap.
2. To clean charcoal canister filter, remove hoses from canister and apply 43 psi (3 kg/cm 2 ) air pressure to fuel tank port. Hold other top ports closed. Ensure that no carbon comes out of bottom port of canister.

Scheme 87

Fixed Orifice

Visually inspect hose and connections for cracks, leaks or other damage. Clean deposits from orifice with solvent and blow out with compressed air

PCV Valve

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

See also:
• AIRFLOW METER RESISTANCE SPECIFICATIONS
• FUEL DELIVERY