Engine Controls - Basic Testing - 6-cyl Toyota Land Cruiser 80

INTRODUCTION

The following diagnostic steps will help prevent overlooking a simple problem. This is also where to begin diagnosis for a no-start condition.

The first step in diagnosing any driveability problem is verifying the customer's complaint with a test drive under the conditions the problem reportedly occurred.

Before entering self-diagnostics, perform a careful and complete visual inspection. Most engine control problems result from mechanical breakdowns, poor electrical connections or damaged/misrouted vacuum hoses. Before condemning the computerized system, perform each test listed in this article.

Note. Perform all voltage tests with a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure.

VISUAL INSPECTION

Visually inspect all electrical wiring, looking for chafed, stretched, cut or pinched wiring. Ensure electrical connectors fit tightly and are not corroded. Ensure vacuum hoses are properly routed and are not pinched or cut. See VACUUM DIAGRAMS article in this section to verify routing and connections (if necessary). Inspect air induction system for possible vacuum leaks.

Compression

Check engine mechanical condition with a compression gauge, vacuum gauge, or an engine analyzer. See engine analyzer manual for specific instructions.

COMPRESSION SPECIFICATIONS

Exhaust System Backpressure

The exhaust system can be checked with a vacuum or pressure gauge. Remove O2 sensor or air injection check valve (if equipped). Connect a 1-10 psi pressure gauge and run engine at 2500 RPM. If exhaust system backpressure is greater than 2 psi, exhaust system or catalytic converter is plugged.

If a vacuum gauge is used, connect vacuum gauge hose to intake manifold vacuum port and start engine. Observe vacuum gauge. Open throttle part way and hold steady. If vacuum gauge reading slowly drops after stabilizing, exhaust system should be checked for a restriction.

FUEL SYSTEM

Basic diagnosis of fuel system should begin with determining fuel system operation and pressure.

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 PUMP QUICK TEST

1. Turn ignition on, with engine off. Place jumper wire across +B and FP terminals of engine check connector in engine compartment. Refer to the «ENGINE CHECK CONNECTOR LOCATION»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl) table. (Scheme 1)
2. Listen for fuel pump running sound. Feel for pressure in fuel line between filter and fuel rail. Turn ignition off. Remove jumper wire. If fuel pump sound was present and fuel hose showed pressure, go to «FUEL SYSTEM PRESSURE TEST»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl__fuel-system-pressure-test).
3. If no pressure or fuel pump sound was present, connect a jumper wire from battery source to FP terminal of engine check connector.
4. If fuel pump does not run or no fuel pressure is felt in line, check for defective fuel pump. Check for open circuit between engine check connector and fuel pump or for poor fuel pump ground. See appropriate wiring diagram in WIRING DIAGRAMS article in this section in this section. NOTE: All models use in-tank fuel pump. Fuel pump contains internal relief valve and check valve.
5. If fuel pump ran after battery source was connected to FP terminal in step 3), check EFI main relay and related wiring. Also check EFI and IGN fuses. See «FUEL PUMP CONTROL CIRCUIT»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl). For more information on wiring, see appropriate wiring diagram in WIRING DIAGRAMS article in this section.

ENGINE CHECK CONNECTOR LOCATION

Scheme 1

FUEL SYSTEM PRESSURE TEST

Note. Before testing fuel pressure, check all fuel delivery and return lines for leaks.

Scheme 2

Scheme 3

Scheme 4

1. Ensure battery is fully charged. Turn ignition off. Disconnect negative battery cable. Place container or shop towel under cold start injector. Disconnect cold start injector (if equipped). Slowly loosen cold start injector or No. 3 fuel supply pipe union bolt to relieve fuel pressure.
2. Remove union bolt and gaskets. Install fuel pressure gauge to cold start injector delivery pipe. (Scheme 2)off excess fuel.
3. Install jumper wire between engine check connector FP and +B pins. Refer to the «ENGINE CHECK CONNECTOR LOCATION»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl) table. Also (Scheme 1)ect negative battery cable, and turn ignition on, with engine off. Measure fuel pressure. Fuel pressure should be same as unregulated pressure. See «FUEL PUMP PERFORMANCE»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl) table.
4. If fuel pressure is high, replace fuel pressure regulator. If fuel pressure is low, check fuel hoses and connections, fuel pump, fuel filter, and fuel pressure regulator
5. Remove jumper wire installed in step 3). Start engine. Disconnect vacuum sensing hose from fuel pressure regulator, and plug hose end. Fuel pressure regulator is mounted on fuel rail.
6. Measure unregulated fuel pressure at idle speed. See the «FUEL PUMP PERFORMANCE»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl) table. With engine still idling, reconnect fuel pressure regulator vacuum hose.
7. Measure regulated pressure at idle. If regulated pressure is not as specified, check vacuum sensing hose to fuel pressure regulator. On models so equipped, check fuel pressure-up system. See & I - SYS/COMP TESTS article in this section.
8. Stop engine. Note fuel pressure. Leave fuel pressure gauge attached to engine for at least 5 minutes. Residual fuel pressure after 5 minutes should be at least 21 psi (1.5 kg/cm 2 ).
9. If pressure is not as specified, check for leaking injectors, faulty fuel pressure regulator or bad check valve in fuel pump. Relieve fuel system pressure. Remove fuel pressure gauge. Install cold start injector. Run engine and check for fuel leaks.

Note. For more information on checking fuel injectors and other fuel sub-systems, see I - SYS/COMP TESTS article in this section.

FUEL PUMP PERFORMANCE

EFI Main Relay

1. EFI fuse supplies constant battery voltage to EFI main relay. EFI main relay provides battery voltage to +B terminal of circuit opening relay and engine check connector.
2. If fuel pump does not turn on when +B and FP pins are jumpered with ignition on, check EFI main relay. (Scheme 5)heck EFI main relay circuit. Depending on model, relay may either be turned on directly by ignition switch or by M-REL terminal of ECU. For more information on wiring, see WIRING DIAGRAMS article in this section in this section.

Scheme 5

Scheme 6

Circuit Opening Relay

1. Circuit opening relay controls fuel pump circuit. ECU receives an input signal at STA terminal when engine is cranking. This starter signal is also applied to terminal STA of circuit opening relay.
2. Starter signal energizes circuit opening relay during cranking, which in turn activates fuel pump. On all models except Supra (Turbo), fuel pump switch in airflow meter provides relay ground. On Supra (Turbo), circuit opening relay is grounded by ECU through FC terminal.

Fuel Pump Relay & Fuel Pump Resistor (Supra)

These models use a separate fuel pump relay and resistor between circuit opening relay and fuel pump.

Note. For more information on testing relays and fuel system components, see I - SYS/COMP TESTS article in this section.

DIAGNOSTIC CODES (EXCEPT SUPRA TURBO)

Note. ECU is programmed to detect ignition problems. Checking for trouble codes can speed up diagnosis. If ECU detects a problem, a diagnostic code will be set in memory. For information on system self-diagnostic capabilities and how to retrieve codes, see TESTS W/CODES article in this section.

Code 12 (No RPM Signal)

ECU will store Code 12 in memory if it does not receive signal from either NE pick-up coil (RPM) or "G" pick-up coil (crank position) terminal within 2 seconds of engine cranking.

Code 13 (No RPM Signal)

ECU will store Code 13 in memory if it does not receive signal from NE pick-up coil (RPM) terminal when engine speed is above 1000 RPM.

Code 14 (Ignition Signal Problem)

ECU will store Code 14 in memory if it does not receive IGF (ignition detection) signal a 6 to 8 times.

SPARK TEST (EXCEPT SUPRA TURBO)

1. On models with integral ignition coil, disconnect spark plug wires. Remove spark plugs. Install spark plugs to each spark plug wire. Ground spark plug.
2. On models with external ignition coil, disconnect high tension (coil) wire from distributor. Hold wire about 1/2" away from ground. CAUTION: To prevent gasoline from being injected, DO NOT crank engine for longer than 2 seconds.
3. On all models, crank engine and check for spark. If spark does not occur, check ignition coil, ignitor and distributor connections.
4. If connections are good, check resistance of high tension wires. See «IGNITION HIGH-TENSION WIRE RESISTANCE (EXCEPT SUPRA TURBO)»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl) table. If resistance is within specification, go to next step. If resistance is not within specification, replace wires.
5. Check power supply to ignition coil and ignitor. Place ignition switch in ON position. Check for voltage at ignition coil positive terminal. If voltage is present, go to next step. If voltage is not present, check wiring between ignition switch, coil and ignitor.
6. Check ignition coil resistance. Refer to the «IGNITION COIL RESISTANCE TESTS (EXCEPT SUPRA TURBO)»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl) . If ignition coil resistance is not as specified, replace coil. If coil resistance is within specification, go to next step.
7. Check pick-up coil resistance. Refer to the appropriate «PICK-UP COIL RESISTANCE TEST (EXCEPT SUPRA TURBO)»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl) . If resistance is within specification, go to next step. If pick-up coil resistance is not as specified, replace pick-up coil or distributor assembly.
8. Check air gap between reluctor and pick-up coil. Refer to the «PICK-UP COIL AIR GAP CHECK (EXCEPT SUPRA TURBO)»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl__pick-up-coil-air-gap-check-except) . If air gap is correct, go to next step. If air gap is incorrect, replace distributor assembly.
9. Check ignition IGT signal from ECU. See appropriate CODE 14 chart in TESTS W/CODES article in this section. If IGT signal is okay, replace ignitor.

Note. A loss of either IGT or IGF signal will cause a no-start condition.

IGNITION HIGH-TENSION WIRE RESISTANCE (EXCEPT SUPRA TURBO)

Primary Coil Resistance Test

1. Disconnect ignition coil so it is isolated from remainder of system. Using an ohmmeter, measure resistance between coil positive (+) and negative (-) terminals. (Scheme 7)
2. If primary resistance is not within specification, replace ignition coil. See «IGNITION COIL RESISTANCE (EXCEPT SUPRA TURBO)»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl) table. If resistance is within specification, proceed to SECONDARY COIL RESISTANCE TEST below.

Scheme 7

Scheme 8

Secondary Coil Resistance Test

1. Disconnect ignition coil so it is isolated from remainder of system. Using an ohmmeter, measure resistance between coil positive (+) terminal and coil tower. (Scheme 9)ee the appropriate «IGNITION COIL RESISTANCE (EXCEPT SUPRA TURBO)»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl) table.
2. If resistance is not within specification, replace ignition coil. If resistance is within specification, proceed to «PICK-UP COIL RESISTANCE TEST (EXCEPT SUPRA TURBO)»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl).

Scheme 9

Scheme 10

IGNITION COIL RESISTANCE (EXCEPT SUPRA TURBO) - Ohms @ 68°F (20°C)

Cressida & Supra (Non-Turbo)

1. Measure resistance of pick-up coil between terminals G1 and G(-), G2 and G(-) and NE and G(-). (Scheme 11)
2. If resistance is not within specification, replace distributor. See «PICK-UP COIL RESISTANCE (EXCEPT SUPRA TURBO)»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl) table. If resistance is within specification, proceed to «PICK-UP COIL AIR GAP CHECK (EXCEPT SUPRA TURBO)»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl__pick-up-coil-air-gap-check-except).

Scheme 11

Land Cruiser

1. Measure pick-up coil resistance between terminals "G" and G(-) and between terminals NE and G(-). (Scheme 12)
2. If resistance is not within specification, replace distributor. See «PICK-UP COIL RESISTANCE (EXCEPT SUPRA TURBO)»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl) table. If resistance is within specification, proceed to «PICK-UP COIL AIR GAP CHECK (EXCEPT SUPRA TURBO)»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl__pick-up-coil-air-gap-check-except).

Scheme 12

PICK-UP COIL RESISTANCE (EXCEPT SUPRA TURBO)

PICK-UP COIL AIR GAP CHECK (EXCEPT SUPRA TURBO)

1. Using a flat, non-magnetic feeler gauge, check air gap between signal rotor and pick-up coil projection. (Scheme 13)
2. Air gap should be at least.008 in. (.20 mm). If air gap is not within specification, replace distributor.

Scheme 13

Scheme 14

DIAGNOSTIC CODES (SUPRA TURBO)

Note. ECU is programmed to detect ignition problems. Checking for trouble codes can speed up diagnosis. If ECU detects a problem, a diagnostic code will be set in memory. For information on system self-diagnostic capabilities and how to retrieve codes, see TESTS W/CODES article in this section.

ECU will store Code 12 in memory if it does not receive signal from either NE pick-up coil (RPM) or "G" pick-up coil (crank position) terminal within 2 seconds of engine cranking.

ECU will store Code 13 in memory if it does not receive signal from NE pick-up coil (RPM) terminal when engine speed is above 1000 RPM.

ECU will store Code 14 in memory if it does not receive IGF (ignition detection) signal 3 times in succession.

Note. A loss of IGT, IGDA or IGDB signal will cause a no-start condition.

SPARK TEST (SUPRA TURBO)

1. Remove duct between air cleaner and intake plenum air connector. Disconnect cruise control, accelerator and throttle cables (automatic transmission only). Label and remove 6 hoses from idle speed control pipe.
2. Remove 2 bolts and idle speed control pipe from intake plenum air connector. Remove oxygen sensor wire from clamps. Disconnect hose from PCV pipe. Remove PCV pipe from cylinder head covers and throttle body.
3. Disconnect hose from intake plenum air connector. Remove 2 bolts, loosen clamps and remove intake plenum air connector. Remove oil filler cap. Remove 5 nuts from ignition coil pack cover labeled TOYOTA TURBO, and lift off cover.
4. Disconnect No. 1 and No. 2 wires, and clamp away from ignition coil. Move ignition coil pack with bracket aside, and remove all spark plug wires from spark plugs. Remove spark plugs. CAUTION: Ignition coil primary or ignitor circuit damage can result if each spark plug is not securely grounded.
5. Install oil filter cap. Install spark plug wires onto original 6 spark plugs. Ground each spark plug securely. Disconnect solenoid resistor block and cold start injector connector.
6. Cold start injector is on bottom of air intake chamber. Solenoid resistor block is on top of right shock tower (4-wire connector). Crank engine and check for consistent Blue spark across plug gaps.
7. If all spark plugs do not fire, verify camshaft sensor moves when engine is cranked. Check ignition feed to coil pack and ignitor circuits. See IGNITION FEED CIRCUIT TEST under «IGNITION COIL (SUPRA TURBO)»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl) . Verify camshaft sensor signals are received by ECU. See «IGNITOR TEST»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl) .
8. If one or 2 spark plugs show inconsistent spark across gap, test particular coil pack for ignition coil primary resistance and plug wire resistance. See «IGNITION COIL RESISTANCE (SUPRA TURBO)»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl) and «IGNITION HIGH-TENSION WIRE RESISTANCE (SUPRA TURBO)»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl) tables.

IGNITION HIGH-TENSION WIRE RESISTANCE (SUPRA TURBO)

IGNITION SYSTEM CONNECTION CHECKS (SUPRA TURBO)

1. With ignition switch in OFF position, check connections of all 3 ignition coil primary circuits. (Scheme 15)for loose and corroded connections. Tighten and clean connections as required.
2. Check connection on primary feed wire to coil and ignitor. If loose or corroded connections exist, repair and repeat SPARK TEST. If no spark output exists and/or no problems are located, proceed to «IGNITION COIL (SUPRA TURBO)»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl).

Scheme 15

Ignition Feed Circuit Test

1. Disconnect ignition feed 2-pin connectors from coil packs. Turn ignition on. Measure voltage between terminal No. 1 (battery feed) and ground. (Scheme 16)
2. With ignition on, 12 volts should be present. If 12 volts are not present, repair open circuit between ignition switch and battery feed to coil pack. If no battery feed problems are detected, go to PRIMARY COIL RESISTANCE below.

Scheme 16

Primary Coil Resistance

Using an ohmmeter, measure resistance between positive and negative terminals of each ignition coil. (Scheme 17)e ignition coil if resistance is not to specification. Refer to the IGNITION COIL RESISTANCE (SUPRA TURBO) table. If no problems are detected, proceed to IGNITION COIL GROUND TEST below.

IGNITION COIL RESISTANCE (SUPRA TURBO)

Scheme 17

Ignition Coil Ground Test

Turn ignition off. Disconnect ignition coil connectors. Using ohmmeter, ensure no continuity exists between ignition coil terminals and ground. If continuity exists, replace ignition coil. If no problems are detected, go to IGNITION OPERATIONAL CHECK (SUPRA TURBO) .

Feed To Ignitor Test

1. Turn ignition off. Unplug ignition module 6-pin connector. Ignition module 6-pin module connector is located next to alternator. Turn ignition switch to ON position.
2. Check for 12 volts between terminal No. 3 and ground on harness side connector. (Scheme 18)ect 6-pin connector. If feed voltage is not present, repair open in wiring harness, and retest system. If feed circuit is okay, proceed to «PICK-UP COIL RESISTANCE TEST (SUPRA TURBO)»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl__pick-up-coil-resistance-test-supra-turbo).

Scheme 18

PICK-UP COIL RESISTANCE TEST (SUPRA TURBO)

1. Disconnect negative battery cable. Disconnect camshaft position sensor 4-pin connector. Measure resistance from terminal G(-) to terminals G1, G2 and NE. (Scheme 19)
2. Resistance of each pick-up coil should be 185-265 ohms. If resistance is not as specified, replace camshaft position sensor assembly. If pick-up coil resistance is within specification, proceed to «PICK-UP COIL AIR GAP CHECK (SUPRA TURBO)»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl__pick-up-coil-air-gap-check-supra).

Scheme 19

PICK-UP COIL AIR GAP CHECK (SUPRA TURBO)

1. Using flat, non-magnetic feeler gauge, check air gap between signal rotor and pick-up coil projection. (Scheme 20)p should be.008-.016" (.20-.40 mm).
2. If air gap is incorrect, replace camshaft position sensor assembly. If air gap clearance is within specification, proceed to «IGNITOR TEST (SUPRA TURBO)»(/toyota/land-cruiser/80-1989-1994/remont/testing-diagnostics/#engine-controls-basic-testing-6-cyl).

Scheme 20

Ignitor Power Transistor Check

1. Turn ignition off. Unplug ignition module 4-pin connector. Disconnect each ignition coil pack 2-pin connector. Turn ignition on. Connect ohmmeter between terminal No. 2 of third ignition coil and ground. (Scheme 21)
2. Using a 3-volt dry cell battery, apply 3 volts to terminal No. 2 of 4-pin connector. With 3 volts applied, ensure ohmmeter indicates momentary continuity. Connect ohmmeter between terminal No. 2 of first ignition coil and ground.
3. Apply 3 volts to terminal No. 4 of 4-pin connector. With 3 volts still applied to terminal No. 4, also apply 3 volts to terminal No. 2. Ensure ohmmeter indicates momentary continuity. (Scheme 21)t ohmmeter between terminal No. 2 of second ignition coil and ground.
4. Apply 3 volts to terminal No. 3 of 4-pin connector. With 3 volts still applied to terminal No. 3, also apply 3 volts to terminal No. 2. Ensure ohmmeter indicates momentary continuity. (Scheme 21)e ignitor if tests are not as specified.

Scheme 21

IDLE SPEED & IGNITION TIMING

Ensure idle speed and ignition timing are set to specification. For adjustment procedures, see ADJUSTMENTS article in this section.

IDLE SPEED

IDLE SPEED SPECIFICATIONS

IGNITION TIMING

IGNITION TIMING

SUMMARY

If no faults were found while performing BASIC TESTING , proceed to TESTS W/CODES article in this section. If no hard codes are found in self-diagnostics, proceed to TESTS W/O CODES article in this section for diagnosis by symptom (i.e., ROUGH IDLE, NO START, etc.) or intermittent diagnostic procedures.

See also:
• ENGINE CHECK CONNECTOR LOCATION
• FUEL SYSTEM PRESSURE TEST
• PICK-UP COIL AIR GAP CHECK (EXCEPT SUPRA TURBO)
• PICK-UP COIL RESISTANCE TEST (SUPRA TURBO)
• PICK-UP COIL AIR GAP CHECK (SUPRA TURBO)