Escalade, Suburban, Tahoe, Yukon, Denali, DenaliXL, YukonXL 1999-2005

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



4.3L, 5.0L, 5.7L & 7.4L Engines
  1. Remove or disconnect the following:

    Negative battery cable
     
    Wires
     
    Accessory belt(s)
     
    Mounting bracket, if necessary
     
    Alternator

    Click image to see an enlarged view

    Fig. Exploded view of the alternator mounting-Truck shown

     

  2.  

To install:

  1. Install or connect the following:

    Alternator
     
    Mounting bracket. Torque the bolts to 18 ft lbs. (25 Nm).
     
    Mounting bolts. Torque the right bolt to 18 ft lbs. (25 Nm) and left bolt to 37 ft lbs. (50 Nm).
     
    Accessory belt(s)
     
    Wires. Torque the battery feed wire to 71 inch lbs. (8 Nm).
     
    Negative battery cable
     

  2.  

4.8L, 5.3L & 6.0L Engines
  1. Disconnect the negative battery cable.
  2.  
  3. Remove or disconnect the following:

    Accessory drive belt
     
    Engine sight shield, if necessary
     
    Electrical connections from the alternator
     
    Mounting bolts
     
    Alternator

    Click image to see an enlarged view

    Fig. Alternator mounting-4.8L, 5.3L & 6.0L engines; 8.1L similar

     

  4.  

To install:

  1. Install the alternator.
  2.  
  3. Install or connect the following:

    Alternator mounting bolts. Tighten the bolts to 37 ft. lbs. (50 Nm).
     
    Electrical connections to the alternator. Tighten the B+ nut to 13 ft. lbs. (18 Nm).
     
    Engine sight shield, if removed
     
    Accessory drive belt
     

  4.  
  5. Connect the negative battery cable. Tighten to bolt to 13 ft. lbs. (17 Nm).
  6.  

  1. Disconnect the negative battery cable.
  2.  
  3. Remove or disconnect the following:

    Accessory drive belt
     
    Engine sight shield, if necessary
     
    Electrical connections from the alternator
     
    Mounting bolts
     
    Generator

    Click image to see an enlarged view

    Fig. Alternator mounting-4.8L, 5.3L and 6.0L engines

     

  4.  

To install:

  1. Install or connect the following:

    Generator
     
    Generator mounting bolts and tighten to 37 ft. lbs. (50 Nm).
     
    Electrical connections to the alternator. Tighten the B+ nut to 13 ft. lbs. (18 Nm).
     
    Engine sight shield, if removed
     
    Accessory drive belt
     
    Negative battery cable
     

  2.  

4.8L, 5.3L, 6.0L & 6.2L Engines
  1. Disconnect the negative battery cable.
  2.  
  3. Remove or disconnect the following:

    Accessory drive belt
     
    Engine sight shield, if necessary
     
    Electrical connections from the alternator
     
    Mounting bolts
     
    Alternator

    Click image to see an enlarged view

    Fig. Alternator mounting-4.8L, 5.3L, 6.0L and 6.2L engines; 8.1L similar

     

  4.  

To install:

  1. Install the alternator.
  2.  
  3. Install or connect the following:

    Alternator mounting bolts. Tighten the bolts to 37 ft. lbs. (50 Nm) on 2005-06 models or on 2007 models, tighten to 41 ft. lbs. (55 Nm).
     
    Electrical connections to the alternator. Tighten the B+ nut to 80 inch. lbs. (9 Nm).
     
    Engine sight shield, if removed
     
    Accessory drive belt
     

  4.  
  5. Connect the negative battery cable.
  6.  

5.7L & 7.4L Engines
  1. Before servicing the vehicle, refer to the Precautions section.
  2.  
  3. Remove or disconnect the following:

    Negative battery cable
     
    Wires
     
    Accessory belt(s)
     
    Mounting bracket, if necessary
     
    Alternator

    Click image to see an enlarged view

    Fig. Exploded view of the alternator mounting-5.7L and 7.4L Engines

     

  4.  

To install:

  1. Install or connect the following:

    Alternator
     
    Mounting bracket. Torque bolts to 18 ft lbs. (25 Nm).
     
    Mounting bolts. Torque the right mounting bolt to 18 ft lbs. (25 Nm) and left bolt to 37 ft lbs. (50 Nm).
     
    Accessory belt(s)
     
    Wires. Torque the battery feed wire to 71 inch lbs. (8 Nm).
     
    Negative battery cable
     

  2.  

6.5L & 6.6L Engines

NOTE
This procedure applies to both the main and auxiliary alternators.

  1. Disconnect the negative battery cable.
  2.  
  3. Remove or disconnect the following:

    Accessory drive belt
     
    Engine sight shield, if necessary
     
    Electrical connections from the alternator
     
    Mounting bolts
     
    Alternator
     

  4.  
  5. If necessary, remove the cable from the alternator as follows:
    1. Slide the boot down, to reveal the terminal stud.
    2.  
    3. Unfasten the cable nut from the stud, then remove the alternator cable.

      Click image to see an enlarged view

      Fig. Main and auxiliary alternator mounting

    4.  

  6.  

To install:

  1. Connect the alternator cable, secure with the nut and tighten to 80 inch lbs. (9 Nm). Slide the boot back over the terminal stud.
  2.  
  3. Install the alternator.
    NOTE
    Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  4.  
  5. Install or connect the following:

    Alternator mounting bolts and tighten to 37 ft. lbs. (50 Nm)
     
    Electrical connections to the alternator. Tighten the B+ nut to 13 ft. lbs. (18 Nm).
     
    Engine sight shield, if removed
     
    Accessory drive belt
     

  6.  
  7. Connect the negative battery cable.
  8.  

6.5L Engine
Auxiliary

CAUTION
Before servicing any electrical component, the ignition key must be in the OFF or LOCK position and all electrical loads must be OFF, unless instructed otherwise in these procedures. If a tool or equipment could easily come in contact with a live exposed electrical terminal, also disconnect the negative battery cable. Failure to follow these precautions may cause personal injury and/or damage to the vehicle or its components.

  1. Disconnect the battery negative cable.
  2.  
  3. Disconnect the terminal plug from the back of the alternator.
  4.  
  5. Disconnect the battery lead from the back of the alternator.
  6.  
  7. Remove the upper fan shroud if necessary.
  8.  
  9. Remove the drive belt from the alternator.
  10.  
  11. Remove the auxiliary brace bolts.
  12.  
  13. Remove the remaining alternator bracket bolts.
  14.  
  15. Lift the hose from the alternator support.
  16.  
  17. Remove the alternator.

    Click image to see an enlarged view

    Fig. Auxiliary alternator mounting-6.5L engine

  18.  

To install:

  1. Install the alternator.
    NOTE
    Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  2.  
  3. Install the alternator bracket bolts. Tighten the alternator mounting bolts to 37 ft. lbs. (50 Nm).
  4.  
  5. Install the auxiliary brace bolts. Tighten the auxiliary alternator mounting long bolts to 37 ft. lbs. (50 Nm). Tightening specifications include bolts for right mounted brace. Tighten the auxiliary alternator mounting short bolts to 18 ft. lbs. (25 Nm).
  6.  
  7. Place the hose on the alternator support.
  8.  
  9. Install the drive belt to the alternator.
  10.  
  11. Install the upper fan shroud if necessary.
  12.  
  13. Connect the battery lead to the back of the alternator. Tighten the battery terminal nut to 71 inch lbs. (8 Nm).
  14.  
  15. Connect the terminal plug from the back of the alternator.
  16.  
  17. Connect the battery negative cable.
  18.  

Primary

CAUTION
Before servicing any electrical component, the ignition key must be in the OFF or LOCK position and all electrical loads must be OFF, unless instructed otherwise in these procedures. If a tool or equipment could easily come in contact with a live exposed electrical terminal, also disconnect the negative battery cable. Failure to follow these precautions may cause personal injury and/or damage to the vehicle or its components.

  1. Disconnect the battery negative cable.
  2.  
  3. Disconnect the terminal plug from the back of the alternator.
  4.  
  5. Disconnect the battery lead from the back of the alternator.
  6.  
  7. Remove the upper fan shroud as needed.
  8.  
  9. Remove the drive belt from the alternator.
  10.  
  11. Remove the alternator mounting bolts holding the alternator to the bracket.
  12.  
  13. Remove the alternator.

    Click image to see an enlarged view

    Fig. Primary alternator mounting-6.5L engine

  14.  

To install:

  1. Install the alternator.
    NOTE
    Use the correct fastener in the correct location. Replacement fasteners must be the correct part number for that application. Fasteners requiring replacement or fasteners requiring the use of thread locking compound or sealant are identified in the service procedure. Do not use paints, lubricants, or corrosion inhibitors on fasteners or fastener joint surfaces unless specified. These coatings affect fastener torque and joint clamping force and may damage the fastener. Use the correct tightening sequence and specifications when installing fasteners in order to avoid damage to parts and systems.

  2.  
  3. Install the alternator mounting bolts. Tighten the alternator mounting bolts to 50 Nm (37 ft. lbs.).
  4.  
  5. Install the drive belt to the alternator.
  6.  
  7. Install the upper fan shroud as needed.
  8.  
  9. Connect the battery lead to the back of the alternator. Tighten the battery terminal nut to 71 inch lbs. (8 Nm).
  10.  
  11. Connect the terminal plug to the back of the alternator.
  12.  
  13. Connect the battery negative cable.
  14.  

8.1L Engine
  1. Disconnect the negative battery cable.
  2.  
  3. Remove or disconnect the following:

    Electrical connections from the alternator
     

  4.  
  5. Remove the cable from the alternator as follows:
    1. Slide the boot down, to reveal the terminal stud.
    2.  
    3. Unfasten the cable nut from the stud, then remove the alternator cable.

      Accessory drive belt
       
      Mounting bolts
       
      Alternator
       
      Mounting bolts securing the alternator to the brace and bracket
       
      Alternator
       

    4.  

  6.  

To install:

  1. Install or connect the following:

    Alternator
     
    Alternator mounting bolts. Tighten the bolts to 37 ft. lbs. (50 Nm).
     
    Accessory drive belt
     

  2.  
  3. Connect the alternator cable, secure with the nut and tighten to 80 inch lbs. (9 Nm). Slide the boot back over the terminal stud.

    Electrical connections to the alternator
     

  4.  
  5. Connect the negative battery cable.
  6.  

  1. Disconnect the negative battery cable.
  2.  
  3. Remove or disconnect the following:

    Accessory drive belt
     
    Electrical connections from the alternator
     

  4.  
  5. Remove the cable from the alternator as follows:
    1. Slide the boot down, to reveal the terminal stud.
    2.  
    3. Unfasten the cable nut from the stud, then remove the cable.
    4.  

  6.  
  7. Remove the mounting bolts and the alternator.
  8.  

To install:

  1. Install or connect the following:

    Alternator
     
    Alternator mounting bolts and tighten to 37 ft. lbs. (50 Nm)
     
    Accessory drive belt
     
    Cable, secure with the nut and tighten to 80 inch lbs. (9 Nm)
     
    Boot back over the terminal stud.
     
    Electrical connections
     
    Negative battery cable
     

  2.  

  1. Disconnect the negative battery cable.
  2.  
  3. Remove or disconnect the following:

    Electrical connections from the alternator
     

  4.  
  5. Remove the cable from the alternator as follows:
    1. Slide the boot down, to reveal the terminal stud.
    2.  
    3. Unfasten the cable nut from the stud, then remove the alternator cable.

      Accessory drive belt
       
      Mounting bolts
       
      Alternator
       
      Mounting bolts securing the alternator to the brace and bracket
       
      Alternator
       

    4.  

  6.  

To install:

  1. Install or connect the following:

    Alternator
     
    Alternator mounting bolts. Tighten the bolts to 37 ft. lbs. (50 Nm).
     
    Accessory drive belt
     

  2.  
  3. Connect the alternator cable, secure with the nut and tighten to 80 inch lbs. (9 Nm). Slide the boot back over the terminal stud.

    Electrical connections to the alternator
     

  4.  
  5. Connect the negative battery cable.
  6.  

 
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