Aspen 2007, Durango 2006-2007

Alternator

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Diagnosis & Testing



Load Test
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. 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).
  4.  
  5. Increase and hold engine speed to 2000 rpm.
  6.  
  7. Measure the voltage reading at the battery.
  8.  
  9. 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 (regulator), and replacement will fix the problem; however, faulty wiring and other problems can cause the charging system to malfunction. 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.  

No Load Test
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Connect a tachometer to the engine.
    CAUTION
    Ensure that the transmission is in Park and the emergency brake is set. Blocking a wheel is optional and an added safety measure.

  4.  
  5. Turn off all electrical loads (radio, blower motor, wipers, etc.)
  6.  
  7. Start the engine and increase engine speed to approximately 1500 rpm.
  8.  
  9. 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.
  10.  
  11. 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 (regulator), and replacement will fix the problem; however, faulty wiring and other problems can cause the charging system to malfunction. 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.

  12.  
  13. If the voltage is within specifications, proceed to the next test.
  14.  

Voltage Test
  1. Before servicing the vehicle, refer to the Precautions Section.
  2.  
  3. Make sure the engine is OFF , and turn the headlights on for 15-20 seconds to remove any surface charge from the battery.
  4.  
  5. Using a DVOM set to volts DC, probe across the battery terminals.
  6.  
  7. Measure the battery voltage.
  8.  
  9. Write down the voltage reading and proceed to the next test.
  10.  

Removal & Installation



3.7L & 4.7L Engines
  1. Before servicing the vehicle, refer to the precautions section.
  2.  
  3. Remove or disconnect the following:
    NOTE
    There are 1 vertical and 2 horizontal bolts.



    Negative battery cable
     
    Accessory drive belt
     
    Alternator harness connectors
     
    Mounting bolts and alternator
     



    Click image to see an enlarged view

    Fig. Alternator mounting on 3.7L and 4.7L engines. (1) horizontal bolts, (2) vertical bolt, (3) alternator

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To install:

  1. Before servicing the vehicle, refer to the precautions section.
  2.  
  3. Install the alternator and tighten the bolts to the following specifications:

    Short horizontal bolt to 55 ft. lbs. (74 Nm)
     
    Vertical bolt and long horizontal bolt to 40 ft. lbs. (55 Nm)
     

  4.  
  5. Install or connect the following:

    Alternator harness connectors
     
    Accessory drive belt
     
    Negative battery cable
     

  6.  

5.7L Engines
  1. Before servicing the vehicle, refer to the precautions section.
  2.  
  3. Remove or disconnect the following:

    Negative battery cable
     
    Accessory drive belt
     
    Alternator harness connectors
     
    Support bracket nuts and bolt
     
    Mounting bolts and alternator
     

  4.  
  5. Installation is the reverse of removal. Torque the bolts to 30 ft. lbs. (41 Nm).

    Click image to see an enlarged view

    Fig. Alternator mounting-5.7L engine

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