Hyundai Coupes/Sedans 1986-1993 Repair Guide

Diagnosis and Testing

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SERVICE PRECAUTIONS





Do not operate the fuel pump if the fuel system is empty.
 
Do not operate the fuel pump when removed from the fuel tank.
 
Do not reuse fuel hose clamps.
 
Make sure all ECU harness connectors are fastened securely. A poor connection can cause an extremely high surge voltage in the coil and condenser and result in damage to integrated circuits.
 
Keep all ECU parts and harnesses dry during service.
 
Do not attempt to disconnect the battery cables with the engine running.
 
Do not disconnect wiring connector with the engine running, unless instructed to do so.
 
Do not depress the accelerator pedal when starting.
 
Do not rev up the engine immediately after starting or just prior to shutdown.
 
Do not apply battery power directly to injectors.
 
To avoid damage to the ECU, always turn the ignition switch OFF before disconnecting the battery cable.
 
The control harnesses between the ECU and oxygen sensor are shielded wires with the shield grounded to the body in order to prevent the influence of ignition noises and radio interference. When the shielded wire is faulty, the control harness must be replaced.
 
Before removing or installing any part(s), always check the self-diagnosis system.
 

SELF-DIAGNOSIS SYSTEM



Except 1993 Scoupe

The Engine Control Unit (ECU) is capable of monitoring both input and output signals. When the ECU notices that an irregularity has continued for a specified time or longer, it memorizes a trouble code and outputs the signal to the self-diagnosis output terminal. There are 14 diagnosis items, including the normal state. The trouble codes can be read out with a voltmeter or multi-tester.

Among the self-diagnosis items, a Malfunction Indicator Light (MIL) comes ON to notify the driver of the emission control items when an irregularity is detected.

Generally, the MIL will come ON for 5 seconds when the ignition switch is turned ON .

Always check that the MIL illuminates for approximately 5 seconds, when the ignition switch is turned ON. If the light does not illuminate, check for an open circuit harness, blown fuse or blown bulb.

1993 Scoupe

The Engine Control Unit (ECU) is capable of monitoring both input and output signals. When the ECU notices that an irregularity has continued for a specified time or longer, it memorizes a trouble code and outputs the signal to the self-diagnosis output terminal. There are 29 diagnosis items, including the normal state. The trouble codes can be read out with the On-Board Diagnostics (OBD) lamp or multi-tester.

Among the self-diagnosis items, the On-Board Diagnostics (OBD) lamp comes ON to notify the driver of the emission control items when an irregularity is detected.

Generally, the OBD will come ON for 5 seconds when the ignition switch is turned ON .

Always check that the OBD illuminates for approximately 5 seconds, when the ignition switch is turned ON. If the light does not illuminate, check for an open circuit harness, blown fuse or blown bulb.

READING CODES



See Figures 1 through 7

The trouble codes for the 1993 Scoupe cannot be read using a voltmeter.

Using Voltmeter
EXCEPT 1993 SCOUPE
  1. Connect the voltmeter to the self-diagnostic connector, across the MPI diagnosis and ground terminals.
  2.  



Click image to see an enlarged view

Fig. Fig. 1: MPI system diagnosis connector-Sonata shown, Elantra similar

  1. Turn the ignition switch ON . The ECU diagnostics memory will immediately start.
  2.  
  3. If the voltmeter displays a steady needle sweep, the system is normal and no codes are in the memory.
  4.  
  5. If the voltmeter displays a steady HIGH signal, the ECU is damaged.
  6.  
  7. If the ECU has detected a malfunction, the voltmeter will deflect, indicating the diagnostic code.
  8.  
  9. Record the codes displayed by the voltmeter needle deflections.
  10.  
  11. The ECU will continue to send any memorized trouble codes to the self-diagnostic for as long as the ignition is ON , or until the codes have been cleared from memory.
  12.  

Using Multi-Use Tester (MUT)
  1. Turn the ignition switch OFF .
  2.  
  3. Connect the Multi-Use Tester (MUT), (Tool 09391-33200 or equivalent), to the diagnosis connector in the fuse box.
  4.  



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Fig. Fig. 2: Connecting multi-use tester to vehicle

  1. Connect the power-source terminal of the MUT to the cigarette lighter switch.
  2.  



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Fig. Fig. 3: Using an auxiliary power source, if performing test during cranking.



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Fig. Fig. 4: Diagnostic trouble code list-Except 1993 Scoupe



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Fig. Fig. 5: Diagnostic trouble code pattern list-Except 1993 Scoupe



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Fig. Fig. 6: Diagnostic trouble code pattern list (continued)-Except 1993 Scoupe

  1. Turn the ignition switch ON and the ECU memory contents will immediately start.
  2.  



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Fig. Fig. 7: Diagnostic trouble code pattern list (continued)-Except 1993 Scoupe

  1. Read the self-diagnosis output and check output of correct code.
  2.  
  3. After recording the fault codes, check and repair each part according to the check items in the Diagnosis Charts.
  4.  

If the battery voltage is too low, trouble codes cannot be read. If the battery or the ECU connector is disconnected, the diagnosis memory will be erased.

When the ignition key is in the START position, the cigarette lighter power is OFF. If it is necessary to perform tests, using the MUT in the crank mode, an auxiliary power supply will be necessary. Use the battery clamp harness provided.

Using On-Board Diagnostic (OBD) Lamp
1993 SCOUPE

See Figures 8, 9 and 10

  1. Turn the ignition switch to the ON position (do not start the engine).
  2.  
  3. Ground the L wire (No. 10 pin) of the diagnostic connector, for 2.5 seconds, then remove the ground.
  4.  



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Fig. Fig. 8: Diagnostic connector ground wire (pin No. 10)-1993 Scoupe



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Fig. Fig. 9: Trouble code display pattern using On-Board Diagnostic lamp-1993 Scoupe



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Fig. Fig. 10: Diagnostic trouble code pattern list-1993 Scoupe

  1. The first output is the fault code stored or the "NO FAULT DETECTED CODE" 4444.
  2.  



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Fig. Fig. 11: Diagnostic trouble code pattern list (continued)-1993 Scoupe

  1. Each blink code is repeated continuously until the next step is ordered.
  2.  
  3. The next code can be read by grounding the L wire (No. 10 pin) again for 2.5 seconds. After that the next code will follow. Continue this until all codes are displayed.
  4.  
  5. The last code displayed will be the end of output code (3333).
  6.  

CLEARING CODES



After completion of the repair or correction of the problem:

  1. Turn the ignition switch OFF .
  2.  
  3. Disconnect the negative battery cable for approximately 15 seconds.
  4.  
  5. Reconnect the negative battery cable.
  6.  
  7. Check that no trouble codes are displayed by the MUT.
  8.  
  9. Remove the Multi-Use Tester (MUT).
  10.  

FUEL PUMP



See Figures 12 and 13

Operational Check
  1. Turn the ignition switch OFF .
  2.  
  3. Apply battery voltage to the fuel pump drive connector and check that the fuel pump operates. The fuel pump is located inside the fuel tank and can be heard without removing the fuel tank cap.
  4.  
  5. Pinch the high pressure hose and note if fuel pressure is felt.
  6.  

FUEL PRESSURE



Relieving
  1. Disconnect the fuel pump harness at the rear of the tank.
  2.  
  3. Start engine and allow to idle.
  4.  
  5. After engine stalls, fuel pressure is reduced.
  6.  
  7. Disconnect the negative battery cable and reconnect the fuel pump wiring.
  8.  
  9. Remove the fuel tank cap.
  10.  

When disconnecting any fuel system hoses, always place a shop towel to prevent residual fuel from spraying.

Testing
  1. Relieve fuel system pressure.
  2.  
  3. Turn ignition switch OFF and disconnect the negative battery cable.
  4.  

When disconnecting any fuel system hoses, always place a shop towel to prevent residual fuel from spaying.

  1. Disconnect the high pressure hose at the delivery side. Using a fuel pressure gauge and adapter (09353-24000 or equivalent), install the adapter to the delivery pipe.
  2.  
  3. Connect the negative battery cable.
  4.  
  5. Activate the fuel pump, by applying battery voltage to the fuel pump drive terminal. Check that there is no leakage from pressure gauge or connections.
  6.  



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Fig. Fig. 12: Fuel pump drive terminal location-Excel

  1. Disconnect the vacuum hose from the pressure regulator and plug.
  2.  



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Fig. Fig. 13: Fuel pump drive terminal location-Sonata

  1. Operate the engine at idle and check the fuel pressure. Fuel pressure should be 47-50 psi (330-350 kPa).
  2.  
  3. Reconnect the vacuum hose to the pressure regulator. With the engine idling, fuel pressure should be 39 psi (270 kPa).
  4.  
  5. If the specified values are not met, make the necessary repairs, as indicated in the diagnosis chart.
  6.  
  7. Shut the engine OFF. Check that the fuel pressure is maintained at the value indicated in Step 8, for approximately 5 minutes.
  8.  
  9. Relieve the fuel pressure.
  10.  
  11. Remove the fuel pressure gauge and reconnect the high pressure hose, using a new O-ring.
  12.  
  13. Start the engine and check for leaks.
  14.  

IDLE SPEED CONTROL MOTOR



Testing
SONATA

See Figure 14

  1. Disconnect the ISC motor connector.
  2.  
  3. Check the continuity of the ISC motor coil between terminal 1 and 2. Reading should be 5-35 ohms at 68°deg;F (20°deg;C).
  4.  



Click image to see an enlarged view

Fig. Fig. 14: Check ISC motor for continuity

  1. Connect a 6 volt DC power supply (4 dry cells) between terminal 1 and 2. Check that the servo operates.
  2.  

Do not apply voltages higher than 6 volts DC or locking of the servo gears can result.

  1. If the servo does not operate, replace it as an assembly.
  2.  

CONTROL RELAY



Failure of the control relay will interrupt power supply to the fuel pump, injectors and the ECU, resulting in a No Start condition.

Testing
ELANTRA

See Figure 15



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Fig. Fig. 15: Control relay functional schematic-Elantra

  1. Apply 12 volts (+) power supply to terminal 6 of the control relay. Note the voltage at terminal 2 and at terminal 1 when the negative (-) lead is connected and disconnected from terminal 8. Should indicated 12 volts when connected and 0 volt when disconnected.
  2.  
  3. Apply 12 volts (+) power supply to terminal 3 of the control relay. Note the voltage at terminal 4 when the negative (-) lead is connected and disconnected from terminal 9. Should indicated 12 volts when connected and 0 volt when disconnected.
  4.  
  5. Connect the negative lead (-) of the power supply to terminal 10 of the control relay. Check for continuity between terminals 3 and 4 when the positive (+) terminal is connected and disconnected to terminal 7. Should indicate continuity when connected.
  6.  
  7. If the results are not satisfactory, replace the control relay.
  8.  

EXCEL

See Figures 16



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Fig. Fig. 16: Control relay functional schematic-Excel

  1. Check for continuity between the terminals when the relay coil is not energized, as follow:
    1. Terminals 1 and 4. Should be infinity (non-conductive).
    2.  
    3. Terminals 2 and 8. Should indicate a value of approximately 95 ohms.
    4.  
    5. Terminals 3 and 8. Should indicate a value of approximately 95 ohms.
    6.  
    7. Terminals 6 and 7. Should indicate a value of approximately 35 ohms.
    8.  
    9. Terminals 1 and 2. Should be infinity (non-conductive).
    10.  

  2.  
  3. Connect the ohmmeter across terminals 1 and 4. Jumper terminal 6 to ground and momentarily apply battery voltage to terminal 7 (Relay energized). Should indicate a value of 0 ohm.
  4.  
  5. Connect the ohmmeter across terminals 1 and 2. Jumper terminal 5 to ground and momentarily apply battery voltage to terminal 7 (Relay energized). Should indicate a value of 0 ohm.
  6.  
  7. If the results are not satisfactory, replace the control relay.
  8.  

1991-92 SCOUPE

See Figure 17



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Fig. Fig. 17: Control relay functional schematic-1991-92 Scoupe

  1. Check for continuity between the terminals when the relay coil is not energized, as follow:
    1. Terminals 2 and 8. Should indicate a value of approximately 95 ohms.
    2.  
    3. Terminals 3 and 8. Should indicate a value of approximately 35 ohms.
    4.  
    5. Terminals 5 and 7. Should indicate continuity, but only in one direction.
    6.  

  2.  
  3. Connect the ohmmeter across terminals 1 and 4. Jumper terminal 6 to ground and momentarily apply battery voltage to terminal 7 (Relay energized). Should indicate a value of 0 ohm. When the relay is de-energized it should indicate infinity.
  4.  
  5. Connect the ohmmeter across terminals 1 and 3. Jumper terminal 5 to ground and momentarily apply battery voltage to terminal 7 (Relay energized). Should indicate a value of 0 ohm. When the relay is de-energized it should indicate infinity.
  6.  
  7. If the results are not satisfactory, replace the control relay.
  8.  

SONATA

See Figures 18



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Fig. Fig. 18: Checking control relay-Sonata

  1. Check for continuity between the terminals when the relay coil is not energized, as follow:
    1. Terminals 1 and 4. Should be infinity (non-conductive).
    2.  
    3. Terminals 2 and 8. Should indicate a value of approximately 95 ohms.
    4.  
    5. Terminals 3 and 8. Should indicate a value of approximately 95 ohms.
    6.  
    7. Terminals 6 and 7. Should indicate a value of approximately 35 ohms.
    8.  
    9. Terminals 1 and 3. Should be infinity (non-conductive).
    10.  

  2.  
  3. Connect the ohmmeter across terminals 1 and 4. Jumper terminal 6 to ground and momentarily apply battery voltage to terminal 7 (Relay energized). Should indicate a value of 0 ohm.
  4.  
  5. Connect the ohmmeter across terminals 1 and 3. Jumper terminal 5 to ground and momentarily apply battery voltage to terminal 7 (Relay energized). Should indicate a value of 0 ohm.
  6.  
  7. If the results are not satisfactory, replace the control relay.
  8.  

IDLE SPEED CONTROL SERVO



See Figure 19

Testing
ELANTRA-STEPPER MOTOR TYPE


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Fig. Fig. 19: Idle speed control servo circuit diagram-Elantra

  1. Connect a 6 volt power supply source to the indicated terminals and check if stepper motor movement occurs, as follows:
    1. Positive (+) lead to terminal 2 and 5 of the connector.
    2.  
    3. Negative (-) lead to terminal 1 and 4.
    4.  
    5. Negative (-) lead to terminal 3 and 4.
    6.  
    7. Negative (-) lead to terminal 3 and 6.
    8.  
    9. Negative (-) lead to terminal 1 and 6.
    10.  

  2.  
  3. Measure the resistance between the respective terminals, as follows:
    1. Terminals 2-3 and 1-28-33 ohms at 68°deg;F (20°deg;C)
    2.  
    3. Terminals 5-4 and 6-28-33 ohms at 68°deg;F (20°deg;C)
    4.  

  4.  
  5. If the results are not as indicated in Step 1 and 2, replace the idle speed control servo.
  6.  

SCOUPE-DC MOTOR TYPE
  1. Check for an open-circuit or short-circuit to ground between the ECU terminals 1 and 2 to the ISC servo.
  2.  
  3. Disconnect the ISC servo connector.
  4.  
  5. Check for continuity across the terminals of the ISC. Should indicate a reading of 5-35 ohms at 68°deg;F (20°deg;C).
  6.  
  7. Connect a 6 volt DC power source across the ISC and check that the ISC servo operates.
  8.  

Do not apply more than 6 volts DC. A higher voltage may cause the servo gears to lock.

  1. If the results are not as indicated, replace the ISC servo.
  2.  

IDLE SPEED ACTUATOR (ISA)



Testing
1993 SCOUPE

See Figure 20

  1. Disconnect the connector at the ISA.
  2.  



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Fig. Fig. 20: Idle speed actuator resistance checking-1993 Scoupe

  1. Measure the resistance between the terminals at the ISA side of the connector. Resistance should be:
    1. Between terminals 1 and 2: 13 ohms at 68°deg;F
    2.  
    3. Between terminals 2 and 3: 14 ohms at 68°deg;F
    4.  

  2.  
  3. Reconnect the ISA connector.
  4.  

INJECTOR



Testing

The easiest way to test the operation of the fuel injectors is to listen for a clicking sound coming from the injectors while the engine is running. This is accomplished using a mechanic's stethoscope, or a long screwdriver. Place the end of the stethoscope or the screwdriver (tip end, not handle) onto the body of the injector. Place the ear pieces of the stethoscope in your ears, or if using a screwdriver, place your ear on top of the handle. An audible clicking noise should be heard; this is the solenoid operating. If the injector makes this noise, the injector driver circuit and computer are operating as designed. Continue testing all the injectors this way.


CAUTION
Be extremely careful while working on an operating engine, make sure you have no dangling jewelry, extremely loose clothes, power tool cords or other items that might get caught in a moving part of the engine.

All Injectors Clicking

If all the injectors are clicking, but you have determined that the fuel system is the cause of your driveability problem, continue diagnostics. Make sure that you have checked fuel pump pressure as outlined earlier in this section. An easy way to determine a weak or unproductive cylinder is a cylinder drop test. This is accomplished by removing one spark plug wire at a time, and seeing which cylinder causes the least difference in the idle. The one that causes the least change is the weak cylinder.

If the injectors were all clicking and the ignition system is functioning properly, remove the injector of the suspect cylinder and bench test it. This is accomplished by checking for a spray pattern from the injector itself. Install a fuel supply line to the injector (or rail if the injector is left attached to the rail) and momentarily apply 12 volts DC and a ground to the injector itself; a visible fuel spray should appear. If no spray is achieved, replace the injector and check the running condition of the engine.

One or More Injectors Are Not Clicking

See Figures 21, 22, 23 and 24



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Fig. Fig. 21: Unplug the fuel injector connector



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Fig. Fig. 22: Probe the two terminals of a fuel injector to check it's resistance



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Fig. Fig. 23: Plug the correct "noid" light directly into the injector harness connector



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Fig. Fig. 24: If the correct "noid" light flashes while the engine is running, the injector driver circuit inside the PCM is working

If one or more injectors are found to be not operating, testing the injector driver circuit and computer can be accomplished using a "noid" light. First, with the engine not running and the ignition key in the OFF position, remove the connector from the injector you plan to test, then plug the "noid" light tool into the injector connector. Start the engine and the "noid" light should flash, signaling that the injector driver circuit is working. If the "noid" light flashes, but the injector does not click when plugged in, test the injector's resistance. resistance should be between 13-16 ohms at 68°deg;F (20°deg;C).

If the "noid" light does not flash, the injector driver circuit is faulty. Disconnect the negative battery cable. Unplug the "noid" light from the injector connector and also unplug the PCM. Check the harness between the appropriate pins on the harness side of the PCM connector and the injector connector. Resistance should be less than 5.0 ohms; if not, repair the circuit. If resistance is within specifications, the injector driver inside the PCM is faulty and replacement of the PCM will be necessary.

AIR FLOW SENSOR (AFS)



Testing
EXCEPT 1993 SCOUPE
  1. Disconnect the harness connector to the AFS.
  2.  
  3. Turn the ignition switch ON .
  4.  
  5. Measure the supply voltage at terminal 2.
  6.  
  7. If source volt is not indicated, repair the harness from the control relay or the control relay is faulty.
  8.  
  9. Measure the voltage to terminal 3. Should indicate 4.8-5.2 volts.
  10.  
  11. If not within specification, repair harness and/or connector, as follow:
    1. 1.5L engine-harness from the ECU terminal 3 (C30-1) or ECU is faulty.
    2.  
    3. 1.6L and 2.0L engines-harness from the ECU terminal 3 (C01-1) or ECU is faulty.
    4.  
    5. 3.0L engine-harness from the ECU terminal 15 (C81-1) or ECU is faulty.
    6.  

  12.  
  13. If the harness is okay, its a faulty ECU connection or faulty ECU.
  14.  
  15. Check terminal 6 for continuity to ground. If continuity is not indicated, repair harness from ECU terminals 13 and 20 (except 3.0L engine) or terminal 13 only (3.0L engine).
  16.  
  17. If the harness is okay, substitute a known good ECU.
  18.  
  19. If problem still exist, replace the AFS.
  20.  

1993 SCOUPE
  1. Disconnect the harness connector to the AFS.
  2.  
  3. Turn the ignition switch ON .
  4.  
  5. Measure the supply voltage at terminal 3.
  6.  
  7. If source volt is not indicated, repair the harness from the control relay or the control relay is faulty.
  8.  
  9. Measure the voltage to terminal 4. Should indicate 0.94-0.98 volts at 800 rpm.
  10.  
  11. If not within specification, repair harness from the ECU terminal 4 (H4-7) or ECU is faulty.
  12.  
  13. If the harness is okay, its a faulty ECU connection or faulty ECU.
  14.  
  15. Check terminal 2 for continuity to ground. If continuity is not indicated, repair harness from ECU terminals 2 and 26.
  16.  
  17. If the harness is okay, substitute a known good ECU.
  18.  
  19. If problem still exist, replace the AFS.
  20.  

1993 SCOUPE TURBO

See Figure 25



Click image to see an enlarged view

Fig. Fig. 25: Air flow sensor circuit-1993 Scoupe Turbo

  1. Disconnect the harness connector to the AFS.
  2.  
  3. Turn the ignition switch ON .
  4.  
  5. Measure the supply voltage at terminal 5.
  6.  
  7. If source volt is not indicated, repair the harness from the control relay or the control relay is faulty.
  8.  
  9. Measure the voltage to terminal 3. Should indicate 2.0-2.6 volts at 800 rpm.
  10.  
  11. If not within specification, repair harness from the ECU terminal 3 (H3-7) or ECU is faulty.
  12.  
  13. If the harness is okay, its a faulty ECU connection or faulty ECU.
  14.  
  15. Check terminal 1 for continuity to ground. If continuity is not indicated, repair harness from ECU terminals 1 and 19.
  16.  
  17. If the harness is okay, substitute a known good ECU.
  18.  
  19. If problem still exist, replace the AFS.
  20.  

INTAKE AIR TEMPERATURE SENSOR



Testing
1990 EXCEL
  1. Disconnect the harness connector to the air flow sensor.
  2.  
  3. Measure the resistance between terminals 4 and 6 (AFS side connector). Resistance values should be as follow:
  4.  



32°deg;F (0°deg;C)-5.4-6.6 ohms
 
68°deg;F (20°deg;C)-2.3-2.9.0 ohms
 
176°deg;F (80°deg;C)-0.3-0.4 ohms
 

  1. Measure the resistance while heating the sensor with a hair drier. As the temperature increases, the resistance should decrease.
  2.  
  3. If the readings deviate from these values, replace the air flow sensor.
  4.  

EXCEPT 1990 EXCEL AND 1993 SCOUPE
  1. Disconnect the harness connector to the air flow sensor.
  2.  
  3. Turn the ignition switch ON .
  4.  
  5. Measure the supply voltage at terminal 4 (harness side). Should indicate 4.5-4.9 volts.
  6.  
  7. If not okay, check the harness from ECU terminal 3 (2.0L and 3.0L engines) or ECU terminal 5 (1.5L and 1.6L engines).
  8.  
  9. If the harness is okay, its a faulty ECU connection or faulty ECU.
  10.  
  11. Check terminal 6 for continuity to ground (harness side). If continuity is not indicated, repair harness from ECU terminals 13 and 20 (2.0L engine), terminal 13 (3.0L engine) or ECU is faulty.
  12.  
  13. Measure the resistance across the air flow sensor terminals. Readings should be 2.7 ohms at 68°deg;F (20°deg;C).
  14.  
  15. If the specified values are not obtained, replace the air flow sensor.
  16.  

COOLANT TEMPERATURE SENSOR



Testing
1990 1.5L ENGINE
  1. Disconnect the harness connector from the coolant sensor and remove the sensor from the intake manifold.
  2.  
  3. Measure the resistance across the sensor terminals, with the sensing portion of the sensor immersed in hot water. The sensor housing should be 0.12 inch (3mm) above the surface of the water.
  4.  
  5. Resistance values should be as follow:
  6.  



32°deg;F (0°deg;C)-5.9 ohms
 
68°deg;F (20°deg;C)-2.5 ohms
 
104°deg;F (40°deg;C)-1.1 ohms
 
176°deg;F (80°deg;C)-0.3 ohms
 

  1. If the readings deviate from these values, replace the coolant sensor.
  2.  

EXCEPT 1990 1.5L ENGINE
  1. Disconnect the harness connector to the sensor.
  2.  
  3. Turn the ignition switch ON .
  4.  
  5. Measure the supply voltage at terminal 2 (harness side). Should indicate 4.5-4.9 volts.
  6.  
  7. If not okay, check the harness from ECU terminal 17 or ECU is faulty.
  8.  
  9. If the harness is okay, its a faulty ECU connection or faulty ECU.
  10.  
  11. Check terminal 1 for continuity to ground (harness side). If continuity is not indicated, repair harness from ECU terminals 13 and 23 (1.5L engine), 13 and 20 (1.6L, 1.8L and 2.0L engine) or terminal 13 (3.0L engine).
  12.  
  13. If the harness is okay, its a faulty ECU connection or faulty ECU.
  14.  

THROTTLE POSITION SENSOR



Testing
1990 1.5L ENGINES
  1. Turn the ignition switch OFF and disconnect the harness connector to the TPS sensor.
  2.  
  3. Measure the resistance between terminals 1 and 3 of the TPS. Should indicate a reading between 3.5-6.5 kilo-ohms.
  4.  
  5. Connect an analog-type ohmmeter between terminals 1 and 2.
  6.  
  7. Slowly open the throttle valve form the idle position to the fully open position and check that the resistance value changes smoothly with the opening of the throttle valve. Should indicate a reading between 3.5-6.5 kilo-ohms.
  8.  
  9. If the specified values are not obtained, replace the TPS.
  10.  

1.6L, 1.8L AND 1991-93 1.5L ENGINES-Except 1993 Scoupe
  1. Disconnect the harness connector to the TPS sensor.
  2.  
  3. Turn the ignition switch ON .
  4.  
  5. Measure the supply voltage at terminal 4 (harness side). Should indicate 4.8-5.2 volts.
  6.  
  7. If not okay, check the harness from ECU terminal 14.
  8.  
  9. If the harness is okay, its a faulty ECU connection or faulty ECU.
  10.  
  11. Check terminal 1 for continuity to ground (harness side). If continuity is not indicated, repair harness from ECU terminals 13 and 23 (1.5L engine), 13 and 20 (1.6L engine).
  12.  
  13. If the harness is okay, its a faulty ECU connection or faulty ECU.
  14.  
  15. Check for an open-circuit or short-circuit to ground between the ECU terminal 18 and the TPS terminal 3.
  16.  
  17. If the supply voltage is obtained and the harness is okay, replace the TPS.
  18.  

1993 Scoupe

See Figure 26



Click image to see an enlarged view

Fig. Fig. 26: Throttle position sensor circuit diagram-1993 Scoupe

  1. Disconnect the harness connector to the TPS sensor.
  2.  
  3. Turn the ignition switch ON .
  4.  
  5. Measure the supply voltage at terminal 2 (harness side). Should indicate 4.8-5.2 volts.
  6.  
  7. If not okay, check the harness from ECU terminal 12.
  8.  
  9. If the harness is okay, its a faulty ECU connection or faulty ECU.
  10.  
  11. Check terminal 3 for continuity to ground (harness side). If continuity is not indicated, repair harness from ECU terminals 12 and 53.
  12.  
  13. If the harness is okay, its a faulty ECU connection or faulty ECU.
  14.  
  15. Check for an open-circuit or short-circuit to ground between the ECU terminal 53 and the TPS terminal 1.
  16.  
  17. If the supply voltage is obtained and the harness is okay, replace the TPS.
  18.  

2.0L AND 3.0L ENGINES
  1. Disconnect the harness connector to the TPS sensor.
  2.  
  3. Turn the ignition switch ON .
  4.  
  5. Measure the supply voltage at terminal 3 (harness side). Should indicate 4.8-5.2 volts.
  6.  
  7. If not okay, check the harness from ECU terminal 16.
  8.  
  9. If the harness is okay, its a faulty ECU connection or faulty ECU.
  10.  
  11. Check terminal 2 for continuity to ground (harness side). If continuity is not indicated, repair harness from ECU terminals 13 and 20 (2.0L engine) or terminal 13 only (3.0L engine).
  12.  
  13. If the harness is okay, its a faulty ECU connection or faulty ECU.
  14.  
  15. Check for an open-circuit or short-circuit to ground between the ECU terminal 18 and the TPS terminal 4.
  16.  
  17. If the supply voltage is obtained and the harness is okay, replace the TPS.
  18.  

PHASE SENSOR



Testing
1993 SCOUPE

See Figure 27

  1. Disconnect the connector from the phase sensor. Turn the ignition switch to the ON position.
  2.  



Click image to see an enlarged view

Fig. Fig. 27: Phase Sensor circuit diagram-1993 Scoupe

  1. At the harness side of the connector, check the supply voltage at connector terminal 3. The voltage reading should be 4.8-5.2 volts. If not repair the harness between connector terminal 3 and ECU terminal 12.
  2.  
  3. At the harness side of the connector, check for continuity between terminal 1 and ground. If there is no continuity, check the harness at terminal connector 1.
  4.  
  5. Check for an open or short circuit to ground between the ECU and phase sensor by checking the harness connector terminal 2 to ground and the ECU connector 8 to ground. Repair the harness to ECU terminal 8 if a short is found.
  6.  

WASTE GATE CONTROL SOLENOID VALVE



Testing
1992 SCOUPE TURBO
  1. Disconnect the waste gate solenoid connector.
  2.  
  3. Measure the resistance between the terminals of the valve. The resistance should be approximately 1 mega-ohm at 68°deg;F.
  4.  
  5. If the resistance is far out of specification, the waste gate control solenoid valve should be replaced.
  6.  

CURB IDLE RPM



Checking
  1. Operate the engine until operating temperature is reached.
  2.  
  3. Turn OFF all accessories. Place the gear selector in P (automatic transaxle) or N (manual transaxle).
  4.  
  5. Set the steering wheel in straight ahead position. Apply the parking brake and block the drive wheels.
  6.  
  7. Check that the electric cooling fan is OFF.
  8.  
  9. Stop the engine and connect a tachometer and timing light. If available, the Multi-Use Tester (MUT) (Tool 09391-33200 or equivalent) may be used (Press Code 22 and read the idle rpm).
  10.  
  11. Operate the engine at curb idle.
  12.  
  13. Check basic ignition timing and adjust, if necessary. Timing should be 5-7 degrees BTDC.
  14.  
  15. Operate the engine for more than 5 seconds between 2000-3000 rpm.
  16.  
  17. Operate the engine at idle for 2 minutes; then check the curb idle rpm. Should be 600-700 rpm.
  18.  

Idle speed adjustment is usually unnecessary, since the ECU controls the idle speed.

  1. If the curb idle rpm is not within specifications, use the following procedures:
    1. 1.5L and 2.4L Engines-go to Idle Speed Control and TPS system adjustment.
    2.  
    3. 1.6L, 2.0L and 3.0L Engines-go to Basic Idle Speed Adjustment.
    4.  

  2.  

IDLE SPEED CONTROL (ISC) ANDTHROTTLE POSITION SENSOR (TPS)



See Figures 28

Adjustment
1.5L AND 2.4L ENGINES
  1. Operate the engine until operating temperature is reached.
  2.  
  3. Turn OFF all accessories. Place the gear selector in P (automatic transaxle) or N (manual transaxle).
  4.  
  5. Set the steering wheel in straight ahead position. Apply the parking brake and block the drive wheels.
  6.  
  7. Loosen the accelerator cable.
  8.  
  9. Connect a digital type voltmeter between terminals 1 and 2 of the TPS. Insert the voltmeter probes at rear of the TPS connector. Do not disconnect the TPS connector from the throttle body.
  10.  
  11. Turn the ignition switch to the ON position for approximately 15 seconds; then check to be sure the idle speed control servo if fully retracted to the curb idle position. Do not start the engine.
  12.  

When the ignition switch is first turned ON, the ISC plunger extends to the fast idle position; then after 15 seconds, it retracts to curb idle position.



Click image to see an enlarged view

Fig. Fig. 28: TPS terminal identification-1.5L engine

  1. Turn the ignition switch OFF.
  2.  
  3. Disconnect the ISC motor connector and secure the ISC motor at the fully retracted position.
  4.  
  5. In order to prevent the throttle valve from sticking, open it 2 or 3 times; then release it to let it click shut, and sufficiently loosen the fixed Speed Adjusting Screw (SAS).
  6.  
  7. Start the engine and let it run at idle speed.
  8.  
  9. Check that the curb idle speed is within specifications.
  10.  
  11. If the curb idle speed is not within specifications, adjust the ISC adjusting screw to obtain the specified value.
  12.  

The curb idle speed on a new vehicle driven less than 300 miles (500 Km) may be 20-100 rpm lower than specifications, but no adjustment is necessary. If the engine stalls or the engine speed is too low, clean the throttle valve area.

  1. Tighten the fixed Speed Adjusting Screw (SAS) until the engine speed starts to increase; then loosen it until the engine speed ceases to drop (touch point) and then loosen a half turn from the touch point.
  2.  
  3. Stop the engine.
  4.  
  5. Turn the ignition switch to the ON and check that the TPS output voltage is within specifications. Should be 0.48-0.52 volts.
  6.  
  7. If adjustment is necessary, loosen the TPS mounting screws and turn the TPS until the specified value is obtained. Tighten the TPS mounting screws.
  8.  
  9. Turn the ignition switch OFF.
  10.  
  11. Adjust the accelerator cable play: Automatic transmission-0.12-0.2 in. (3-5mm). All others-0.04-0.08 in. (1-2mm).
  12.  
  13. Connect the ISC motor connector.
  14.  
  15. Disconnect the voltmeter, and connect the TPS connector.
  16.  
  17. Start the engine and check that the idle speed is correct.
  18.  
  19. Turn the ignition switch OFF and erase any fault code stored in the system memory.
  20.  

BASIC IDLE SPEED



See Figures 29, 30, 31 and 32

Adjustment
1.6L, 1.8L AND 2.0L ENGINES
  1. Operate the engine until operating temperature is reached.
  2.  
  3. Turn OFF all accessories. Place the gear selector in P (automatic transaxle) or N (manual transaxle).
  4.  
  5. Set the steering wheel in straight ahead position. Apply the parking brake and block the drive wheels.
  6.  
  7. Loosen the accelerator cable.
  8.  
  9. Connect the Multi-Use Tester (MUT) to the diagnostic connector in the fuse box. If the MUT is not used, connect a tachometer to the engine and ground the self-diagnostic terminal.
  10.  
  11. Ground the ignition timing adjustment terminal.
  12.  
  13. Operate the engine for more than 5 seconds between 2000-3000 rpm.
  14.  
  15. Operate the engine at idle for 2 minutes; then check the curb idle speed. Should be 700-800 rpm.
  16.  
  17. If the curb idle speed is not within specifications, turn the Speed Adjusting Screw (SAS) until the specified value is obtained.
  18.  

If the idle speed is higher than specified, even with the SAS fully closed, check whether the idle switch (fixed SAS) moving mark exists or not. If it is found that the switch has moved, repair as required.



Click image to see an enlarged view

Fig. Fig. 29: Ignition timing adjustment terminal-1.6L and 1.8L engines

  1. Turn the ignition switch OFF .
  2.  
  3. Disconnect the ground lead from the ignition timing adjusting terminal and remove the test equipment.
  4.  
  5. Operate the engine for approximately 10 minutes and check that the engine is in normal idling condition.
  6.  



Click image to see an enlarged view

Fig. Fig. 30: Ignition timing adjustment terminal-2.0L and 3.0L engines

3.0L ENGINE
  1. Run the engine until operating temperature is reached.
  2.  
  3. Turn OFF all accessories. Place the gear selector in P (automatic transaxle) or N (manual transaxle).
  4.  
  5. Set the steering wheel in straight ahead position. Apply the parking brake and block the drive wheels.
  6.  
  7. Loosen the accelerator cable.
  8.  
  9. Connect the Multi-Use Tester (MUT) to the diagnostic connector in the fuse box. If the MUT is not used, connect a tachometer to the engine and ground the ignition timing adjustment terminal.
  10.  
  11. Operate the engine at idle and check ignition timing. Timing should be 3-7 degrees BTDC.
  12.  
  13. Turn the ignition switch OFF and ground the self-diagnostic check terminal.
  14.  
  15. Operate the engine for more than 5 seconds between 2000-3000 rpm.
  16.  
  17. Operate the engine at idle for 2 minutes; then check the curb idle speed. Should be 650-750 rpm.
  18.  
  19. If the curb idle speed is not within specifications, turn the Speed Adjusting Screw (SAS) until the specified value is obtained.
  20.  

If the idle speed is higher than specified, even with the SAS fully closed, check whether the idle switch (fixed SAS) moving mark exists or not. If it is found that the switch has moved, repair as required.

  1. Turn the ignition switch OFF .
  2.  
  3. Disconnect the ground lead from the ignition timing adjusting terminal and self-diagnosis check terminal. Remove the test equipment.
  4.  
  5. Clear the diagnostic memory.
  6.  
  7. Adjust the tension of the acceleration cable.
  8.  
  9. Operate the engine for approximately 10 minutes and check that the engine is in normal idling condition.
  10.  

THROTTLE POSITION SENSOR (TPS)



Adjustment
2.0L ENGINE
  1. Connect the MUT to the diagnostic connector in the fuse box. If the MUT is not used, connect a digital-type voltmeter, using special service tool (09351-33000 or equivalent).
  2.  

Do not disconnect the ECU connector from the ECU.

  1. Turn the ignition switch ON . Do not start the engine.
  2.  
  3. Check the TPS output voltage. If the MUT is used, press code No. 14 and read the voltage. Voltage should be 0.480-0.520.
  4.  
  5. If not within specifications, loosen the TPS mounting screws and adjust by turning the TPS. Tighten the TPS mounting screws.
  6.  
  7. Turn the ignition switch OFF .
  8.  
  9. Erase the ECU memory.
  10.  

3.0L ENGINE
  1. Loosen the acceleration cable tension.
  2.  
  3. Connect the MUT to the diagnostic connector in the fuse box. If the MUT is not used, connect a digital-type voltmeter between terminals 2 and 4 of the TPS.
  4.  

Do not disconnect the TPS.

  1. Turn the ignition switch ON . Do not start the engine.
  2.  
  3. Check the TPS output voltage. Voltage should be 0.48-0.56. volts.
  4.  
  5. If not within specifications, loosen the TPS mounting screws and adjust by turning the TPS. Tighten the TPS mounting screw.
  6.  
  7. Turn the ignition switch OFF .
  8.  
  9. Start the engine and check the idle speed.
  10.  
  11. Erase the ECU memory.
  12.  
  13. Adjust the accelerator cable.
  14.  

IDLE POSITION SWITCH (FIXED SAS)



Adjustment
2.0L AND 3.0L ENGINES
  1. Loosen the accelerator cable tension.
  2.  
  3. Disconnect the idle switch (fixed SAS) harness connector.
  4.  
  5. Loosen the idle switch (fixed SAS) locknut.
  6.  
  7. Turn the idle switch counterclockwise until the throttle valve closes.
  8.  
  9. Connect an ohmmeter between the terminal of the switch and body.
  10.  
  11. Adjust the idle switch until continuity is indicated. Then turn the idle switch the amount of additional turns indicated:
    1. 2.0L engine-turn the idle switch an additional 1 1 / 4 turns.
    2.  
    3. 3.0L engine-Then turn the idle switch and additional 1 1 / 4 turns.
    4.  

  12.  
  13. Tighten the locknut, while keeping the switch from moving. Reconnect the harness connector.
  14.  
  15. Adjust the accelerator cable.
  16.  
  17. Adjust the curb idle speed and TPS.
  18.  

 
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