Subaru Car 1998-05

Alternator

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Diagnosis & Testing





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Fig. Schematic for testing the alternator-1997

  1. Remove the four through bolts and disassemble the alternator.
  2.  
  3. Check for continuity between the diode lead and positive side heat sink. The positive diode is in good condition if resistance is 1 ohm or less only in the direction from the diode lead to heat sink.
  4.  
  5. Check for continuity between the negative side heat sink and diode lead. The negative diode is in good condition if resistance is 1 ohm or less only in the direction from the heat sink to diode lead.
  6.  
  7. Measure the slip ring outer diameter. If the slip ring is less than 0.870 in. (22.1 mm), replace the rotor assembly.
  8.  
  9. Check the resistance between slip rings using circuit tester. If the resistance is not 1.8-2.2 ohms, replace the rotor assembly.
  10.  
  11. Inspect the stator coil for continuity between each end of the lead wires. If resistance is 1 mega-ohm or more, the lead wire is broken, and so replace the stator assembly.
  12.  
  13. Inspect the stator coil for continuity between stator core and each end of lead wire. If resistance is 1 ohm or less, the stator coil is grounded, and so replace the stator assembly.
  14.  
  15. Check the front ball bearing. If the resistance is felt while rotating, or if abnormal noise is heard, replace the ball bearing.
  16.  

Alternator Speed At 13.5 Volts
  1. Refer to the diagram, and open switch SW1 while closing switch SW2.
  2.  
  3. Slowly raise the alternator speed and record the voltage level.
  4.  
  5. If the alternator is functioning correctly, at 900 rpm, the voltage should be 13.5 volts.
  6.  

Measuring Output Current
  1. Refer to the diagram, and set the variable resistor to its minimum resistance.
  2.  
  3. Close switches SW1 and SW2.
  4.  
  5. Turn the alternator while keeping the voltage constant by adjusting the variable resistor. Measure the current level at 1250, 2500 and 5000 rpm. If the alternator is functioning correctly, at 1250 rpm, the alternator should be producing at least 18 amps of current. At 2500 rpm, the unit should produce at least 49 amps, and at 5000 rpm, the alternator should produce at least 58 amps of current.
  6.  

Measuring Regulated Voltage
  1. Make sure the battery is firmly connected and fully charged.
  2.  
  3. Refer to the diagram, and open switch SW1 while closing switch SW2.
  4.  
  5. Turn the alternator at 5000 rpm and record the voltage.
  6.  
  7. If the alternator is functioning correctly, the voltage should be between 14.3-14.8 volts.
  8.  

Installation



  1. Install or connect the following:

    Alternator into the vehicle
     
    Alternator to bracket bolts
     
    Front side V-belt and cover
     
    Connector and terminal to the alternator
     
    Negative battery cable
     

  2.  
  3. Check and adjust the belt tension.
  4.  

Removal



  1. Remove or disconnect the following:

    Negative battery cable
     
    Connector and terminal from the alternator
     
    V-belt cover
     
    Front side V-belt
     
    Alternator to bracket bolts
     
    Alternator from the vehicle
     

  2.  

Removal & Installation



  1. Remove or disconnect the following:

    Negative battery cable
     
    Connector and terminal from the alternator
     
    V-belt cover, if equipped
     
    Front side V-belt
     
    Alternator to bracket bolts
     
    Alternator from the vehicle
     

  2.  

To install:

  1. Install or connect the following:

    Alternator into the vehicle
     
    Alternator to bracket bolts
     
    Front side V-belt
     
    V-belt cover, if equipped
     
    Connector and terminal to the alternator
     
    Negative battery cable
     

  2.  
  3. Check and adjust the belt tension.
  4.  

  1. Remove or disconnect the following:

    Negative battery cable
     
    Connector and terminal from the alternator
     
    V-belt cover, if equipped
     
    Front side V-belt
     
    Alternator to bracket bolts
     
    Alternator from the vehicle
     

  2.  

To install:

  1. Install or connect the following:

    Alternator into the vehicle
     
    Alternator to bracket bolts
     
    Front side V-belt
     
    V-belt cover, if equipped
     
    Connector and terminal to the alternator
     
    Negative battery cable
     

  2.  
  3. Check and adjust the belt tension.
  4.  

 
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