Engine Controls - Basic Testing Toyota Land Cruiser 70

INTRODUCTION

Note. California and Federal applies to installed emission equipment, which may be verified by underhood emission decal. California emissions may be available in other states. References to California models applies to California emission vehicles.

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 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 the VACUUM DIAGRAMS article 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 engine analyzer. See engine analyzer manual for specific instructions.

COMPRESSION SPECIFICATIONS

FUEL SYSTEM

Basic diagnosis of fuel system should begin by checking fuel pump operation and fuel pressure.

FUEL PUMP OPERATION

Note. Fuel pump operation may be checked by using scan tester or by applying battery voltage to electric fuel pump.

Checking Fuel Pump Operation Using Scan Tester

1. Install scan tester on data link connector No. 3. (Scheme 1) Turn ignition on. DO NOT start engine.
2. Using scan tester manufacturer's instructions, activate electric fuel pump. Listen for fuel pump operating sound and feel for pressure in fuel line near fuel filter. Turn ignition off. Remove scan tester. If fuel pump operates, check fuel pressure. See «FUEL PRESSURE»(/toyota/land-cruiser/70-1984-2007/remont/testing-diagnostics/#engine-controls-basic-testing__fuel-pressure).
3. If fuel pump does not operate, EFI main relay, circuit opening relay or fuel pump relay (if used) may be defective. For relay application and explanation of relay operation, see «FUEL PUMP CONTROL CIRCUIT»(/toyota/land-cruiser/70-1984-2007/remont/testing-diagnostics/#engine-controls-basic-testing__fuel-pump-control-circuit).
4. If relays are okay, check wiring circuit and fuses. If fuel pump does not operate, check for defective fuel pump or defective fuel pump ground. See wiring diagram in the WIRING DIAGRAMS article.

Fuel Pump Operation By Applying Battery Voltage To Electric Fuel Pump

1. Remove second seat, scuff plate, step plate, floor mats and cover plate on floor panel for access to electrical connector at fuel pump.
2. Disconnect electrical connector for fuel pump. NOTE: Electrical connector for fuel pump is located near fuel pump.
3. Connect battery voltage to specified terminals on fuel pump to activate fuel pump. (Scheme 2) Listen for fuel pump operating sound and feel for pressure in fuel line near fuel filter. If fuel pump operates, check fuel pressure. See «FUEL PRESSURE»(/toyota/land-cruiser/70-1984-2007/remont/testing-diagnostics/#engine-controls-basic-testing__fuel-pressure). Disconnect battery voltage from fuel pump.
4. If fuel pump fails to operate, replace fuel pump. If fuel pump will not operate while trying to start engine, EFI main relay, circuit opening relay or fuel pump relay (if used) may be defective. For explanation of relay operation, see «FUEL PUMP CONTROL CIRCUIT»(/toyota/land-cruiser/70-1984-2007/remont/testing-diagnostics/#engine-controls-basic-testing__fuel-pump-control-circuit).
5. If relays are okay, check wiring circuit, fuses and fuel pump ground. See wiring diagram in the WIRING DIAGRAMS article. Rein-stall electrical connector and remaining components.

Scheme 1

Scheme 2

FUEL PRESSURE

Note. In-tank fuel pump is used. Fuel pump contains internal relief valve and check valve.

1. Ensure battery is fully charged and ignition is off. Disconnect negative battery cable.
2. Note location of fuel pressure gauge installation. (Scheme 3) Place container under delivery pipe or fuel filter. Cover union bolt with shop towel. Slowly loosen union bolt to relieve fuel pressure.
3. Remove union bolt and gaskets. Install Fuel Pressure Gauge (SST 09268-45012) using NEW gaskets. (Scheme 3) Tighten union bolt. Reconnect negative battery cable.
4. Install scan tester on data link connector No. 3. (Scheme 1) Using scan tester manufacturer's instructions, activate electric fuel pump and note fuel pressure. Fuel pressure should be within specification. See «FUEL PUMP PERFORMANCE»(/toyota/land-cruiser/70-1984-2007/remont/testing-diagnostics/#engine-controls-basic-testing) table. NOTE: Fuel pump may also be activated by connecting battery voltage to specified terminals on fuel pump. (Scheme 2)
5. If fuel pressure exceeds specification, replace fuel pressure regulator. If fuel pressure is less than specified, check for defective fuel lines, connections, fuel pump, fuel filter, fuel pressure regulator or fuel pressure control Vacuum Switching Valve (VSV) if equipped.
6. Remove scan tester from data link connector No. 3. Start engine and allow to idle. Disconnect and plug vacuum line at fuel pressure regulator. Note fuel pressure.
7. Reconnect vacuum hose on fuel pressure regulator and note fuel pressure. Fuel pressure should be within specification. See the «REGULATED FUEL PRESSURE»(/toyota/land-cruiser/70-1984-2007/remont/testing-diagnostics/#engine-controls-basic-testing) table.
8. If fuel pressure is not within specification, check for defective vacuum hose or fuel pressure regulator. Shut engine off and note fuel pressure.
9. Fuel pressure should hold at least 21 psi (1.5 kg/cm 2 ) for a minimum of 5 minutes. If fuel pressure does not hold as specified, check for defective fuel pump, fuel injector or fuel pressure regulator.
10. Disconnect negative battery cable. Remove fuel pressure gauge. Reinstall union bolt using NEW gaskets. Tighten union bolt. Install negative battery cable.

Scheme 3

Note. For more information on checking fuel injectors and other fuel sub-systems, see the SYSTEM/COMPONENT TESTS article.

FUEL PUMP PERFORMANCE

REGULATED FUEL PRESSURE

FUEL PUMP CONTROL CIRCUIT

Note. For information on testing relays and fuel system components, see the SYSTEM/COMPONENT TESTS article. Relays may be identified by illustration in the THEORY/OPERATION article. Vehicles are equipped with different combinations of fuel system electrical components. For complete wiring circuit of electrical components on a specific model, see wiring diagram in WIRING DIAGRAMS article.

EFI Main Relay

The EFI fuse supplies constant battery voltage to EFI main relay. When EFI main relay is energized by MRLY terminal of Engine Control Module (ECM), the EFI main relay provides battery voltage to circuit opening relay, data link connector No. 1 and various other electrical components. The EFI main relay also provide battery voltage to +B terminal of ECM when ignition is turned on. The EFI main relay is located in engine compartment relay box.

Circuit Opening Relay

Circuit opening relay controls fuel pump circuit. When EFI main relay is energized, EFI main relay provides battery voltage to circuit opening relay. When ignition is turned on, voltage is supplied to circuit opening relay. Fuel pump control side of circuit opening relay ground circuit is controlled at Engine Control Module (ECM) terminal FC. When circuit opening relay is energized, circuit opening relay then provides voltage to fuel pump relay for fuel pump operation.

Fuel Pump Relay & Fuel Pump Resistor

Fuel pump relay receives voltage from circuit opening relay to operate the fuel pump. Fuel pump operating speed may be varied by the ECM. When ECM grounds fuel pump relay and relay contacts close, voltage is supplied through fuel pump resistor to the fuel pump. This changes fuel pump operating speed.

SPARK TEST

1. Disconnect high tension coil wire from distributor. Hold the coil wire approximately 1/2" away from body or engine ground. CAUTION: To prevent gasoline from being injected, DO NOT crank engine for longer than 2 seconds.
2. Crank engine and check for spark. If spark does not occur, check ignition coil, ignitor and distributor electrical connections.
3. If electrical connections are okay, using ohmmeter, check resistance of spark plug wire. Replace spark plug wire if resistance is not within specification. See «SPARK PLUG WIRE RESISTANCE SPECIFICATIONS»(/toyota/land-cruiser/70-1984-2007/remont/testing-diagnostics/#engine-controls-basic-testing) table. If resistance is within specification, proceed to step 4). SPARK PLUG WIRE RESISTANCE SPECIFICATIONS Application Maximum Ohms Land Cruiser 25,000 Per Wire
4. Check voltage at ignition coil and ignitor. Turn ignition on. Ensure voltage exists at ignition coil positive terminal. If voltage exists, proceed to step 5). If voltage does not exist, check wiring between ignition switch, ignition coil and ignitor. See wiring diagram in the WIRING DIAGRAMS article.
5. Check ign. coil resistance. See «IGNITION COIL RESISTANCE»(/toyota/land-cruiser/70-1984-2007/remont/testing-diagnostics/#engine-controls-basic-testing__ignition-coil-resistance) . Replace ignition coil if resistance is not within specification. If ignition coil resistance is within specification, proceed to step 6).
6. Check pick-up coil resistance. See procedures under «PICK-UP COIL RESISTANCE»(/toyota/land-cruiser/70-1984-2007/remont/testing-diagnostics/#engine-controls-basic-testing__pick-up-coil-resistance) . Replace pick-up coil or distributor assembly if pick-up coil resistance is not within specification. If pick-up coil resistance is within specification, proceed to step 7).
7. Check resistance of crankshaft position sensor. See «CRANKSHAFT POSITION SENSOR»(/toyota/land-cruiser/70-1984-2007/remont/testing-diagnostics/#engine-controls-basic-testing__crankshaft-position-sensor) . If crankshaft position sensor is okay, proceed to next step.
8. Check pick-up coil air gap. See «PICK-UP COIL AIR GAP»(/toyota/land-cruiser/70-1984-2007/remont/testing-diagnostics/#engine-controls-basic-testing__pick-up-coil-air-gap) . If pick-up coil air gap is incorrect, replace distributor assembly. If pick-up coil air gap is correct, proceed to step 10).
9. Check ignition IGT signal from Engine Control Module (ECM). If ignition IGT signal from ECM is defective a diagnostic trouble code will be set in the ECM memory to indicate a ignitor circuit malfunction. See the TESTS W/CODES article for diagnostic trouble code. If IGT signal is okay, substitute another ignitor and recheck system operation.

CRANKSHAFT POSITION SENSOR

1. Disconnect electrical connector for crankshaft position sensor. Crankshaft position sensor is located on bottom of front cover, near front of oil pan and crankshaft pulley. (Scheme 4)
2. Using ohmmeter, measure resistance between terminals NE- and NE+ on crankshaft position sensor. (Scheme 5) Replace crankshaft position sensor if resistance is not 1630-2740 ohms at 14-122°F (-10-50°C) and 2065-3225 ohms at 122-212°F (50-100°C). Reconnect electrical connector.

Scheme 4

Scheme 5

IGNITION COIL RESISTANCE

1. Disconnect wiring from ignition coil so ignition coil is isolated from system. Using ohmmeter, check ignition coil primary resistance between ignition coil positive (+) and negative (-) terminals. (Scheme 6)
2. Check ignition coil secondary resistance between ignition coil positive (+) terminal and high tension terminal (coil wire tower). (Scheme 7) Replace ignition coil if resistance is not within specification. See the «IGNITION COIL RESISTANCE»(/toyota/land-cruiser/70-1984-2007/remont/testing-diagnostics/#engine-controls-basic-testing) table.

IGNITION COIL RESISTANCE

Scheme 6

Scheme 7

PICK-UP COIL RESISTANCE

Disconnect electrical connector on distributor and note pick-up coil terminal identification on the distributor. (Scheme 8) Using ohmmeter, measure resistance between specified terminals. See PICK-UP COIL RESISTANCE SPECIFICATIONS table. Replace distributor assembly if pick-up coil resistance is not within specification.

PICK-UP COIL RESISTANCE SPECIFICATIONS

Scheme 8

PICK-UP COIL AIR GAP

1. Using non-magnetic feeler gauge, check air gap between signal rotor and pick-up coil projection. (Scheme 9)
2. Replace distributor assembly if pick-up coil air gap is not within specification. See «PICK-UP COIL AIR GAP SPECIFICATIONS»(/toyota/land-cruiser/70-1984-2007/remont/testing-diagnostics/#engine-controls-basic-testing) table.

PICK-UP COIL AIR GAP SPECIFICATIONS

Scheme 9

IDLE SPEED & IGNITION TIMING

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

SUMMARY

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

See also:
• THEORY/OPERATION
• ADJUSTMENTS
• FUEL PRESSURE
• FUEL PUMP CONTROL CIRCUIT
• FUEL PUMP PERFORMANCE
• IGNITION COIL RESISTANCE
• PICK-UP COIL RESISTANCE
• CRANKSHAFT POSITION SENSOR
• PICK-UP COIL AIR GAP