Grand Cherokee 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



The regulator is a circuit located within the Powertrain Control Module (PCM) and not a separate component. If the Electronic Voltage Regulator (EVR) is faulty, the PCM must be replaced.

5.7L Engines
  1. Before servicing the vehicle, refer to the precautions section.
  2.  
  3. Disconnect negative battery cable at battery.
  4.  
  5. Remove generator drive belt.
  6.  
  7. Unsnap plastic insulator cap from B+ output terminal.
  8.  
  9. Remove B+ terminal mounting nut at rear of generator. Disconnect terminal from generator.
  10.  
  11. Disconnect field wire connector at rear of generator by pushing on connector tab.
  12.  
  13. Remove 2 generator mounting bolts.
  14.  
  15. Remove generator from vehicle.

    Click image to see an enlarged view

    Fig. Alternator mounting-5.7L engine

  16.  

To install:

  1. Position generator to engine and install 2 mounting bolts.
  2.  
  3. Tighten bolts to 30 ft. lbs. (41 Nm).
  4.  
  5. Snap field wire connector into rear of generator.
  6.  
  7. Install B+ terminal eyelet to generator output stud. Tighten mounting nut.
    WARNING
    Never force a belt over a pulley rim using a screwdriver. The synthetic fiber of the belt can be damaged.


    NOTE
    When installing a serpentine accessory drive belt, the belt MUST be routed correctly. The water pump may be rotating in the wrong direction if the belt is installed incorrectly, causing the engine to overheat.

  8.  
  9. Install generator drive belt.
  10.  
  11. Install negative battery cable to battery.
  12.  

Except 5.7L Engine
  1. Before servicing the vehicle, refer to the precautions section.
  2.  
  3. Remove or disconnect the following:
    NOTE
    The 3.7L and 4.7L engines have 1 vertical and 2 horizontal bolts.



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

  4.  

To install:

Click image to see an enlarged view

Fig. 3.7L engine alternator mounting

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

    3.7L engine: Tighten the horizontal bolts to 42 ft. lbs. (57 Nm), then the vertical bolt to 29 ft. lbs. (40 Nm)
     
    4.7L engine: Vertical bolt and long horizontal bolt to 41 ft. lbs. (56 Nm), short horizontal bolt to 55 ft. lbs. (74 Nm)
     

  4.  
  5. Install or connect the following:

    Alternator harness connectors
     
    Accessory drive belt
     
    Negative battery cable
     

  6.  

 
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