Quest 1995-1996

Alternator

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Diagnosis & Testing



Alternator Load Test

Specific to:

Mercury Villager 1993-2000

Nissan Quest 1993-2000

  1. With the engine running, turn on the blower motor and the high beams ( or other electrical accessories to place a load on the charging system).
  2.  
  3. Increase and hold engine speed to 2000 rpm.
  4.  
  5. Measure the voltage reading at the battery.
  6.  
  7. The voltage should increase at least 0.5 volts from the voltage test. If the voltage does not meet specifications, the charging system is malfunctioning.
    NOTE
    Usually under and overcharging is caused by a defective alternator, or its related parts, and replacement will fix the problem; however, faulty wiring and other problems can cause the charging system to malfunction. Further testing, which is not covered by this book, will reveal the exact component failure. Many automotive parts stores have alternator bench testers available for use by customers. An alternator bench test is the most definitive way to determine the condition of your alternator.

  8.  

Alternator No-Load Test

Specific to:

Mercury Villager 1993-2000

Nissan Quest 1993-2000

  1. Connect a tachometer to the engine.
    CAUTION
    Ensure that the transmission is in Park and the emergency brake is set. Blocking a wheel is an added safety measure.

  2.  
  3. Turn off all electrical loads (radio, blower motor, wipers, etc.)
  4.  
  5. Start the engine and increase engine speed to approximately 1500 rpm.
  6.  
  7. Measure the voltage reading at the battery with the engine holding a steady 1500 rpm. Voltage should have raised at least 0.5 volts, but no more than 2.5 volts.
  8.  
  9. If the voltage does not go up more than 0.5 volts, the alternator is not charging. If the voltage goes up more than 2.5 volts, the alternator is overcharging.
    NOTE
    Usually under and overcharging is caused by a defective alternator, or its related parts, and replacement will fix the problem; however, faulty wiring and other problems can cause the charging system to malfunction. Further testing, which is not covered by this book, will reveal the exact component failure. Many automotive parts stores have alternator bench testers available for use by customers. An alternator bench test is the most definitive way to determine the condition of your alternator.

  10.  
  11. If the voltage is within specifications, proceed to the next test.
  12.  

Voltage Test

Specific to:

Mercury Villager 1993-2000

Nissan Quest 1993-2000

  1. Make sure the engine is OFF , and turn the headlights on for 15-20 seconds to remove any surface charge from the battery.
  2.  
  3. Using a DVOM set to volts DC, probe across the battery terminals.
  4.  
  5. Measure the battery voltage.
  6.  
  7. Write down the voltage reading and proceed to the next test.
  8.  

Precautions



Specific to:

Mercury Villager 1993-2000

Nissan Quest 1993-2000

Several precautions must be observed when performing work on alternator equipment.



If the battery is removed for any reason, make sure that it is reconnected with the correct polarity. Reversing the battery connections may result in damage to the rectifier assembly.
 
Never operate the alternator with the main circuit broken. Do not disconnect the battery and alternator leads while the engine is running.
 
Never attempt to polarize an alternator.
 
When charging a battery that is installed in the vehicle, disconnect the negative battery cable.
 
When utilizing a booster battery as a starting aid, always connect it in parallel; negative to negative, and positive to positive.
 
When arc (electric) welding is to be performed on any part of the vehicle, disconnect the negative battery cable and alternator leads.
 

Removal & Installation



Specific to:

Mercury Villager 1993-2000

Nissan Quest 1993-2000

  1. Disconnect the negative battery cable.
  2.  
  3. Raise and safely support the front of the vehicle securely on jackstands.
  4.  
  5. Remove the passenger side engine and transaxle splash shield.
  6.  
  7. Remove the alternator wiring harness bracket bolt from the rear of the alternator.
  8.  
  9. Disconnect the alternator electrical connector from the alternator.
  10.  
  11. Remove the ground wire nut and wire.
  12.  
  13. Remove the B terminal wire boot. Remove the B terminal nut and wire.
  14.  
  15. Loosen the inner and outer alternator to bracket mounting bolts.
  16.  
  17. Loosen the alternator adjustment lock bolt.
  18.  
  19. Turn the alternator adjustment bolt counterclockwise to loosen the belt.
  20.  
  21. Remove the belt from the alternator.
  22.  
  23. Remove the alternator lock bolt and washer.
  24.  
  25. Remove the inner alternator to bracket mounting bolt and two washers.
  26.  
  27. Remove the outer alternator to bracket mounting bolt and two washers.
  28.  
  29. Remove the alternator.
  30.  
  31. The installation is the reverse of removal.
  32.  
  33. Adjust the drive belt. For the procedure, please refer to General Information and Maintenance, Routine Maintenance and Tune-Up, Belts, Adjustment, Alternator.

    Click image to see an enlarged view

    Fig. Alternator wire identification



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    Fig. Disconnect the electrical connector



    Click image to see an enlarged view

    Fig. Disconnect the alternator ground wire, then . . .



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    Fig. . . . pull back the B terminal wire boot to remove the nut



    Click image to see an enlarged view

    Fig. Loosen the alternator adjustment lock bolt and . . .



    Click image to see an enlarged view

    Fig. . . . turn the adjustment bolt to loosen the belt



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    Fig. Inner alternator mounting bolt location



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    Fig. Remove the outer alternator mounting bolt and remove the alternator

  34.  

Testing



Specific to:

Mercury Villager 1993-2000

Nissan Quest 1993-2000

If a problem with the charging system is suspected, check the alternator, ignition switch, and meter fuses before proceeding with the following tests. For fuse location, rating, and replacement procedure, please refer to Chassis Electrical, Circuit Protection.

 
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