Engine Controls - Basic Testing - Efi Toyota Corolla VI

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 the 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.

DO NOT use ignition switch during compression tests on fuel injected vehicles. Use a remote starter to crank engine. Fuel injectors on many models are triggered by ignition switch during cranking mode, which can create a fire hazard or contaminate the engine's oiling system.

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 1 3/4-2 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 TESTING INFORMATION

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

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. (Scheme 2) See ENGINE CHECK CONNECTOR LOCATION table.
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/corolla/vi-1987-1993/remont/testing-diagnostics/#engine-controls-basic-testing-efi__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 poor fuel pump ground. See WIRING DIAGRAMS article. 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/corolla/vi-1987-1993/remont/testing-diagnostics/#engine-controls-basic-testing-efi) in this article. For more information on wiring, see the WIRING DIAGRAMS article in this section.

ENGINE CHECK CONNECTOR LOCATION

Scheme 2

FUEL SYSTEM PRESSURE TEST

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

1. Ensure battery is fully charged. Turn ignition off. Disconnect negative battery cable. On all except Pickup and 4Runner with 3VZ-E, place container or shop towel under cold start injector. Disconnect cold start injector (if equipped) and slowly loosen cold start injector union bolt to relieve fuel pressure. Remove union bolt and 2 gaskets.
2. Install fuel pressure gauge to cold start injector delivery pipe. (Scheme 3) Wipe off excess fuel. On Pickup and 4Runner with 3VZ-E, attach gauge to No. 3 fuel pipe using same method. (Scheme 3)
3. Install jumper wire between engine check connector FP and +B pins. (Scheme 2) See ENGINE CHECK CONNECTOR LOCATION table.
4. Reconnect negative battery cable and turn ignition on, with engine off. Measure fuel pressure. Fuel pressure should be same as unregulated pressure. See appropriate FUEL PUMP PERFORMANCE table.
5. If fuel pressure is high, replace fuel pressure regulator. If fuel pressure is low, check the following: Fuel hoses and connections. Fuel pump. Fuel filter. Fuel pressure regulator.
6. Remove jumper wire installed in step 3). Start engine and run for 2 minutes. Disconnect vacuum sensing hose from fuel pressure regulator and plug hose end. Fuel pressure regulator is mounted on fuel rail. NOTE: On Camry (2VZ-FE), Celica (3S-GTE), Corolla (4A-GE), Land Cruiser, Pickup, Supra Turbo and 4Runner allow engine to idle for 2 minutes to stabilize fuel pressure. These models have a fuel pressure-up system which temporarily increases fuel pressure after a hot start.
7. Measure unregulated fuel pressure at idle speed. See appropriate FUEL PUMP PERFORMANCE table.
8. With engine still idling, reconnect fuel pressure regulator vacuum hose. Measure regulated pressure at idle.
9. If regulated pressure was not as specified, check vacuum sensing hose to fuel pressure regulator. On models so equipped, check fuel pressure-up system. Refer to the I - EFI SYS/COMP TESTS article in this section.
10. Stop engine. Note fuel pressure. Leave fuel pressure gauge attached to engine for at least 5 minutes.
11. Residual fuel pressure after 5 minutes should be at least 21 psi (1.5 kg/cm 2 ). If pressure is not as specified, check for leaking injectors, fuel pressure regulator or bad check valve in fuel pump.
12. 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 the I - EFI SYS/COMP TESTS article in this section.

Scheme 3

Scheme 4

Scheme 5

Scheme 6

4-CYLINDER FUEL PUMP PERFORMANCE

6-CYLINDER FUEL PUMP PERFORMANCE

V6 FUEL PUMP PERFORMANCE

EFI MAIN RELAY

1. The EFI fuse supplies constant battery voltage to the EFI main relay. EFI main relay supplies battery voltage to +B pin of engine check connector. If fuel pump will not turn on when +B and FP pins are jumpered, with ignition on, check EFI main relay. (Scheme 7)and (Scheme 8).
2. Also, check circuit that turns on EFI main relay. 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 the WIRING DIAGRAMS article in this section.
3. On all models, EFI main relay provides battery voltage to +B terminal of circuit opening relay.

CIRCUIT OPENING RELAY

1. Circuit opening relay controls fuel pump circuit. ECU receives an input signal at STA terminal when engine is cranking. This same 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 the fuel pump. On all except Celica, Corolla (4A-FE), Supra (7M-GTE) and Tercel, when airflow meter senses airflow to engine, fuel pump switch in airflow meter provides the relay ground. On Celica, Corolla (4A-FE), Supra (7M-GTE) and Tercel, circuit opening relay is grounded by ECU through FC terminal.

FUEL PUMP RELAY & FUEL PUMP RESISTOR (CELICA TURBO, CRESSIDA & SUPRA)

On these models a separate fuel pump relay and resistor are used between circuit opening relay and fuel pump.

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

Scheme 7

Scheme 8

DIAGNOSTIC CODES

Note. ECU is programmed to detect ignition problems. Checking for trouble codes can speed up your 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 the G - EFI TESTS W/ CODES article.

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) within 2 seconds of engine cranking.

Code 13 (No RPM Signal)

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

Code 14 (Ignition Signal Problem)

ECU will store Code 14 in memory if it does not receive an IGF (ignition detection) signal a specified number of times in succession. See CODE 14 SET SPECIFICATIONS table.

CODE 14 SET SPECIFICATIONS

SPARK TEST

1. On models with integral ignition coil, disconnect spark plug wires. Remove spark plugs. Install spark plugs to each spark plug wire. Ground spark plugs.
2. On models with an 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 more 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 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. See IGNITION COIL RESISTANCE TESTS in this article. 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. See PICK-UP COIL RESISTANCE TEST in this article. 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. See PICK-UP COIL AIR GAP CHECK in this article. 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.

IGNITION HIGH-TENSION WIRE RESISTANCE

Primary Coil Resistance Test

1. Disconnect ignition coil so it is isolated from remainder of system. Using ohmmeter, measure resistance between coil positive (+) and negative (-) terminals. (Scheme 9)through (Scheme 18).
2. If primary resistance is not within specification, replace ignition coil. See appropriate IGNITION COIL RESISTANCE table. If resistance is within specification, proceed to SECONDARY COIL RESISTANCE TEST.

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. See IGNITION COIL RESISTANCE table. (Scheme 9)through (Scheme 18).
2. If resistance is not within specification, replace ignition coil. If resistance is within specification, proceed to PICK-UP COIL RESISTANCE TEST.

IGNITION COIL RESISTANCE

Scheme 9

Scheme 10

Scheme 11

Scheme 12

Scheme 13

Scheme 14

Scheme 15

Scheme 16

Scheme 17

Scheme 18

Camry (2VZ-FE), Pickup (3VZ-E) & 4Runner (3VZ-E)

1. Measure pick-up coil resistance between terminals G1 and G(-), G2 and G(-), and NE and G(-). (Scheme 19)through (Scheme 25).
2. If resistance is incorrect, replace distributor. See PICK-UP COIL RESISTANCE table. If resistance is within specification, proceed to PICK-UP COIL AIR GAP CHECK.

Camry (3S-FE), Land Cruiser & Tercel

1. Measure pick-up coil resistance between terminals "G" and G(-), and between terminals NE and G(-). (Scheme 19)through (Scheme 25).
2. If resistance is not within specification, replace distributor. See PICK-UP COIL RESISTANCE table. If resistance is within specification, proceed to PICK-UP COIL AIR GAP CHECK.

Celica (3S-GTE), Cressida & Supra (Non-Turbo)

1. Measure resistance of pick-up coil between terminals G1 and G(-), G2 and G(-), and NE and G(-). (Scheme 19)through (Scheme 25).
2. If resistance is not within specification, replace distributor. See PICK-UP COIL RESISTANCE table. If resistance is within specification, proceed to PICK-UP COIL AIR GAP CHECK.

Celica (4A-FE) & Corolla (4A-FE)

1. Measure pick-up coil resistance between terminals G(+) and G(-), and between terminals NE(+) and GE(-). (Scheme 19)through (Scheme 25).
2. If resistance is not within specification, replace distributor. See PICK-UP COIL RESISTANCE table. If resistance is within specification, proceed to PICK-UP COIL AIR GAP CHECK.

Celica (5S-FE)

1. Measure pick-up coil resistance between terminals G1 and G(-), and between NE and G(-). (Scheme 19)through (Scheme 25).
2. If resistance is not within specification, replace distributor. See PICK-UP COIL RESISTANCE table. If resistance is within specification, proceed to PICK-UP COIL AIR GAP CHECK.

Corolla (4A-GE)

1. Measure pick-up coil resistance between terminals G(+) and G(-), and between NE(+) and NE(-). (Scheme 19)through (Scheme 25).
2. If resistance is not within specification, replace distributor. See PICK-UP COIL RESISTANCE table. If resistance is within specification, proceed to PICK-UP COIL AIR GAP CHECK.

Pickup (22R-E) & 4Runner (22R-E)

1. Measure resistance of pick-up coil between terminals NE (+) and NE (-). (Scheme 19)through (Scheme 25).
2. If resistance is not within specification, replace distributor. See PICK-UP COIL RESISTANCE table. If resistance is within specification, proceed to PICK-UP COIL AIR GAP CHECK.

PICK-UP COIL RESISTANCE SPECIFICATIONS (1)

Pick-Up Coil Connector ID (Camry 4-Cyl., Land Cruiser & Tercel) Toyota Motor Sales U.S.A., Inc. Scheme 19

Pick-Up Coil Connector ID (Camry V6, Pickup/4Runner V6) Toyota Motor Sales U.S.A., Inc. Scheme 20

Pick-Up Coil Connector ID (Celica & Corolla 4A-FE) Toyota Motor Sales U.S.A., Inc. Scheme 21

Pick-Up Coil Connector ID (Corolla 4A-GE) Toyota Motor Sales U.S.A., Inc. Scheme 22

Pick-Up Coil Connector ID (Pickup/4Runner 4-Cyl.) Toyota Motor Sales U.S.A., Inc. Scheme 23

Pick-Up Coil Connector ID (Celica Turbo, Cressida & Supra Non-Turbo) Toyota Motor Sales U.S.A., Inc. Scheme 24

Pick-Up Coil Connector ID (Celica 5S-FE) Toyota Motor Sales U.S.A., Inc. Scheme 25

PICK-UP COIL AIR GAP CHECK

1. Using a flat, non-magnetic feeler gauge, check air gap between signal rotor and pick-up coil projection. (Scheme 26)through (Scheme 34).
2. Air gap should be within specification. See PICK-UP COIL ADJUSTMENT table. If air gap is not within specification, replace distributor.

PICK-UP COIL ADJUSTMENT

Scheme 26

Scheme 27

Scheme 28

Scheme 29

Scheme 30

Scheme 31

Scheme 32

Scheme 33

Scheme 34

Note. ECU is programmed to detect ignition problems. Checking for trouble codes can speed up your 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 the 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) 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) 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.

1. Remove duct between air cleaner and intake plenum air connector. Disconnect cruise control, accelerator, and throttle cables (automatic transmission only).
2. Remove 6 hoses from idle speed control pipe. 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 2 bolts and disconnect 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 TOYOTA TURBO labeled ignition coil pack cover, and lift off cover.
4. Remove nut and disconnect No. 1 and No. 2 wires and clamp from ignition coil. Move ignition coil pack with bracket out of the way and remove all spark plug wires from spark plugs.
5. Remove all spark plugs. Install oil filter cap. Install spark plug wires onto the original 6 spark plugs. Ground each spark plug securely. CAUTION: Ignition coil primary or ignitor circuit damage can result if each spark plug is not securely grounded.
6. Disconnect solenoid resistor block and cold start injector connector. Cold start injector is on bottom of air intake chamber. Solenoid resistor block is on top of right side shock tower (4-wire connector).
7. Crank engine and check for consistent Blue spark across plug gaps. If all spark plugs do not fire, check ignition feed to coil pack and ignitor circuits. See IGNITION FEED CIRCUIT TEST under IGNITION COIL in this article.
8. Verify camshaft sensor signals are received by ECU. See IGNITOR TEST in this article. Also, verify camshaft sensor moves when engine is cranked.
9. If only one or 2 spark plugs show an inconsistent spark across the gap, test that particular coil pack for ignition coil primary resistance as well as spark plug wire resistance. See IGNITION COIL RESISTANCE and IGNITION HIGH-TENSION WIRE RESISTANCE tables in this article.

IGNITION HIGH-TENSION WIRE RESISTANCE

IGNITION SYSTEM CONNECTION CHECKS

1. With ignition switch in OFF position, check connections of all 3 ignition coil primary circuits. Check for loose connections or corrosion. Tighten and/or clean connections as required.
2. Check connection on primary feed wire to coil and ignitor. If loose or corroded connections exist, correct them and repeat SPARK TEST.
3. If no spark output is observed or no problems were located and resolved in this test, proceed to IGNITION FEED CIRCUIT TEST under IGNITION COIL in this article.

Ignition Feed Circuit Test

1. Disconnect ignition feed 2-pin connectors from coil packs. Turn ignition switch to the ON position. Measure voltage between terminal No. 1 (battery feed) and ground. (Scheme 35)
2. There should be 12 volts present with ignition on. If reading indicates a problem, repair open circuit between ignition switch and battery feed to coil pack. If no battery feed problems are detected, go to PRIMARY COIL RESISTANCE.

Scheme 35

Primary Coil Resistance

Using an ohmmeter, measure resistance between positive and negative terminals of each ignition coil. (Scheme 36) Replace ignition coil if resistance is not to specification. See IGNITION COIL RESISTANCE table. If no problems are detected, proceed to IGNITION COIL GROUND TEST.

Note. It is not possible to check ignition coil secondary resistance.

IGNITION COIL RESISTANCE

Scheme 36

Ignition Coil Ground Test

Turn ignition off. Disconnect ignition coil connectors. Using an ohmmeter, ensure there is no continuity between ignition coil terminals and ground. If there is continuity, replace ignition coil. If no problems are detected, proceed to IGNITION OPERATIONAL CHECK.

Feed To Ignitor Test

Turn ignition off. Unplug ignition module 6-pin connector. Ignition module 6-pin module connector is located next to alternator. Turn ignition switch to the ON position. Check for 12 volts between terminal No. 3 and ground on harness side connector. (Scheme 37) Reconnect 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.

Scheme 37

PICK-UP COIL RESISTANCE

Disconnect negative battery cable and disconnect camshaft position sensor 4-wire connector. Measure resistance from terminal G(-) to terminals G1, G2 and NE. (Scheme 38) Resistance of each pick- up coil should be 140-180 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.

PICK-UP COIL RESISTANCE

Scheme 38

1. Using flat, non-magnetic feeler gauge, check air gap between signal rotor and pick-up coil projection. (Scheme 39) Air gap 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»(/toyota/corolla/vi-1987-1993/remont/testing-diagnostics/#engine-controls-basic-testing-efi).

Scheme 39

Ignitor Power Transistor Check

1. Turn ignition off. Unplug ignition module 4-pin connector. Disconnect each ignition coil pack 2-pin connector.
2. Turn ignition switch to ON position. Connect ohmmeter between terminal No. 2 of third ignition coil and ground. 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. (Scheme 41)
3. Connect ohmmeter between terminal No. 2 of first ignition coil and ground. 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. Check that ohmmeter indicates momentary continuity. (Scheme 41)
4. Connect ohmmeter between terminal No. 2 of second ignition coil and ground. Apply 3 volts to terminal No. 3 of 4-pin connector. With 3 volts still applied to No. 3, also apply 3 volts to terminal No. 2. Ensure ohmmeter indicates momentary continuity. (Scheme 41)

Scheme 40

Scheme 41

IDLE SPEED & IGNITION TIMING

Note. Ensure idle speed and ignition timing are set to specification. For adjustment procedures, see appropriate D - 4-CYL EFI ADJUSTMENTS or D - V6 EFI ADJUSTMENTS article in this section.

IDLE SPEED & MIXTURE

4-CYLINDER IDLE SPEED SPECIFICATIONS

6-CYLINDER IDLE SPEED SPECIFICATIONS

V6 IDLE SPEED SPECIFICATIONS

IGNITION TIMING

4-CYLINDER IGNITION TIMING (Degrees BTDC @ RPM)

6-CYLINDER IGNITION TIMING (Degrees BTDC @ RPM)

V6 IGNITION TIMING (Degrees BTDC @ RPM)

SUMMARY

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

See also:
• FUEL SYSTEM PRESSURE TEST
• FUEL PUMP CONTROL CIRCUIT