Nissan Stanza/200SX/240SX 1982-1992 Repair Guide

Alternator

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ALTERNATOR PRECAUTIONS



To prevent damage to the alternator and regulator, the following precautionary measures must be taken when working with the electrical system.

  1. Never reverse battery connections.
  2.  
  3. Booster batteries for starting must be connected properly. Make sure that the positive cable of the booster battery is connected to the positive terminal of the battery that is getting the boost and negative cable to ground.
  4.  
  5. Disconnect the battery cables before using a fast charger; the charger has a tendency to force current through the diodes in the opposite direction for which they are designed. This burns out the diodes.
  6.  
  7. Never use a fast charger as a booster for starting the vehicle.
  8.  
  9. Never disconnect the voltage regulator while the engine is running.
  10.  
  11. Do not ground the alternator output terminal.
  12.  
  13. Do not operate the alternator on an open circuit with the field energized.
  14.  
  15. Do not attempt to polarize an alternator.
  16.  
  17. When steam cleaning the engine, be careful not to subject the alternator assembly to excessive heat or moisture.
  18.  

REMOVAL & INSTALLATION



  1. Disconnect the negative battery terminal.
  2.  
  3. Disconnect the two lead wires and connector from the alternator.
  4.  
  5. Loosen the drive belt adjusting bolt and remove the belt.
  6.  
  7. Unscrew the alternator attaching bolts and remove the alternator from the vehicle.
  8.  

To install:
  1. Mount the alternator to the engine and partially tighten the attaching bolts.
  2.  
  3. Reconnect the lead wires and connector to the alternator.
  4.  
  5. Install the alternator drive belt.
  6.  
  7. Adjust the alternator belt correctly and completely tighten the mounting bolts.
  8.  

The correct belt tension is about1/4-1/2in. (613mm) play on the longest span of the drive belt. The alternator belt tension is quite critical. A belt that is too tight may cause alternator bearing failure; one that is too loose will cause a gradual battery discharge.

  1. Connnect the battery cable. Start the engine and check for proper operation.
  2.  

TESTING



Voltage Test
  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.  

No-Load Test
  1. Connect a tachometer to the engine.
  2.  


CAUTION
Ensure that the transmission is in Park and the emergency brake is set. Blocking a wheel is optional and an added safety measure.

  1. Turn off all electrical loads (radio, blower motor, wipers, etc.)
  2.  
  3. Start the engine and increase engine speed to approximately 1500 rpm.
  4.  
  5. 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.
  6.  
  7. 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.
  8.  

Usually under and overcharging is caused by a defective alternator, or its related parts (regulator), 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 guide, 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.

  1. If the voltage is within specifications, proceed to the next test.
  2.  

Load Test
  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.
  8.  

Usually under and overcharging is caused by a defective alternator, or its related parts (regulator), 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 guide, 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.

 
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