ES300 1992-1997

Alternator

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Precautions



Specific to:

Lexus ES300 1993-1997

Several precautions must be observed with alternator equipped vehicles to avoid damage to the unit.



If the battery is removed for any reason, make sure it is reconnected with the correct polarity. Reversing the battery connections may result in damage to the 1-way rectifiers.
 
When utilizing a booster battery as a starting aid, always connect the positive to positive terminals and the negative terminal from the booster battery to a good engine ground on the vehicle being started.
 
Never use a fast charger as a booster to start vehicles.
 
Disconnect the battery cables when charging the battery with a fast charger.
 
Never attempt to polarize the alternator.
 
Do not use test lights of more than 12 volts when checking diode continuity.
 
Do not short across or ground any of the alternator terminals.
 
The polarity of the battery, alternator and regulator must be matched and considered before making any electrical connections within the system.
 
Never separate the alternator on an open circuit. Make sure all connections within the circuit are clean and tight.
 
Disconnect the battery ground terminal when performing any service on electrical components.
 
Disconnect the battery if arc welding is to be done on the vehicle.
 

Removal & Installation



Specific to:

Lexus ES300 1992-1993

  1. Disconnect the negative battery cable. Wait at least 90 seconds before performing any other work.

    Click image to see an enlarged view

    Fig. Alternator and related components

  2.  
  3. Remove the 2 bolts and No. 3 right-hand engine mounting stay.
  4.  
  5. Remove the bolt and nut and then remove the No. 2 right-hand engine mounting stay.
  6.  
  7. Remove the drive belt. Refer to Accessory Drive Belts in the Engine Mechanical section.
  8.  
  9. Disconnect the alternator connector.
  10.  
  11. Remove the nut, and disconnect the alternator wire.
  12.  
  13. Disconnect the wire harness from the clip.
  14.  
  15. Remove the pivot bolt, adjusting lock bolt and alternator.
  16.  

To install:

  1. Mount the alternator on the alternator brackets with the pivot and adjusting bolts. Do not tighten the bolts at this time.
  2.  
  3. Connect the alternator connector.
  4.  
  5. Connect the alternator wire with the nut.
  6.  
  7. Install the drive belt.
  8.  
  9. Install the No. 2 stay and tighten the bolts to 55 ft. lbs. (75 Nm), and the nut to 46 ft. lbs. (62 Nm).
  10.  
  11. Install the No. 3 stay and tighten the bolts to 54 ft. lbs. (73 Nm).
  12.  
  13. Connect the negative battery cable.
  14.  
  15. Start the engine.
  16.  
  17. Visually inspect the drive belt and listen for any abnormal vibration.
  18.  
  19. Check the charging system for proper function.
  20.  
  21. Turn the engine off and recheck the belt tension.
  22.  

Specific to:

Lexus ES300 1994-1997

  1. Disconnect the negative battery cable. Wait at least 90 seconds before performing any other work.

    Click image to see an enlarged view

    Fig. Alternator and related components-1996 models shown, other models similar

  2.  
  3. Remove the drive belt. Refer to Accessory Drive Belts in the Engine Mechanical section.
  4.  
  5. Disconnect the alternator connector.
  6.  
  7. Remove the nut, and disconnect the alternator wire.
  8.  
  9. Disconnect the wire harness from the clip.
  10.  
  11. Remove the pivot bolt, adjusting lock bolt and alternator.

    Click image to see an enlarged view

    Fig. Alternator removal/installation

  12.  

To install:

  1. Mount the alternator on the alternator brackets with the pivot and adjusting bolts. Do not tighten the bolts at this time.
  2.  
  3. Connect the alternator connector.
  4.  
  5. Connect the alternator wire with the nut.
  6.  
  7. Install the drive belt.
  8.  
  9. Connect the negative battery cable.
  10.  
  11. Start the engine.
  12.  
  13. Visually inspect the drive belt and listen for any abnormal vibration.
  14.  
  15. Check the charging system for proper function.
  16.  
  17. Turn the engine off and recheck the belt tension.
  18.  

1MZ-FE Engine

Specific to:

Lexus ES300 1993-1997

  1. Disconnect the negative battery cable.
  2.  
  3. Remove the alternator drive belt by loosening the pivot bolt, adjusting lock bolt and the adjusting bolt.
  4.  
  5. Disconnect the electrical connector to the alternator.
  6.  
  7. Remove the nut and disconnect the electrical wire from the alternator.
  8.  
  9. Remove the pivot bolt, plate washer and adjusting lock bolt from the alternator.
  10.  
  11. Remove the alternator from its bracket.
  12.  

To install:

  1. Mount the alternator on the alternator brackets with the pivot and adjusting lock bolt. Do not tighten the bolts at this time.
  2.  
  3. Install the drive belt onto the pulley, making sure the grooves on the belt and the grooves on the pulley are properly aligned.
  4.  
  5. Adjust the drive belt tension by tightening the adjusting bolt. Torque the pivot bolt to 41 ft. lbs. (46 Nm) and the adjusting lock bolt to 13 ft. lbs. (18 Nm).
  6.  
  7. Connect the electrical wire and nut to the alternator.
  8.  
  9. Connect the electrical connector to the alternator.
  10.  
  11. Connect the negative battery cable to the battery.
  12.  
  13. Start the engine and allow it warm.
  14.  
  15. Visually inspect the drive belt and listen for any abnormal vibration.
  16.  
  17. Check the charging system function.
  18.  
  19. Turn the engine off and recheck the belt tension.
  20.  

3vz-FE Engine

Specific to:

Lexus ES300 1993-1997

  1. Disconnect the negative battery cable. Wait at least 90 seconds before performing any other work.
  2.  
  3. Remove the 2 bolts and No. 3 right hand engine mounting stay.
  4.  
  5. Remove the bolt and nut and then remove the No. 2 right hand engine mounting stay.
  6.  
  7. Disconnect the electrical connector and wire (and nut) from the alternator.
  8.  
  9. Unfasten the bolts which attach the adjusting link to the alternator.
  10.  
  11. Remove the alternator drive belt from the pulley.
  12.  
  13. Unfasten the alternator attaching bolt and then withdraw the alternator from its bracket.
  14.  

To install:

  1. Mount the alternator on the alternator brackets with the pivot and adjusting bolts. Do not tighten the bolts at this time.
  2.  
  3. Install the No. 2 stay and tighten the bolts to 55 ft. lbs. (75 Nm), the nut to 46 ft. lbs. (62 Nm). Install the No. 3 stay and tighten the 2 bolts to 54 ft. lbs. (73 Nm).
  4.  
  5. Install the drive belt onto the pulley, making sure the grooves on the belt and the grooves on the pulley are properly aligned.
  6.  
  7. Adjust the drive belt tension and properly tighten the pivot and adjusting bolts.
  8.  
  9. Connect the wire (nut) and connector to the alternator.
  10.  
  11. Connect the negative battery cable.
  12.  
  13. Start the engine.
  14.  
  15. Visually inspect the drive belt and listen for any abnormal vibration.
  16.  
  17. Check the charging system for proper function.
  18.  
  19. Turn the engine off and recheck the belt tension.
  20.  

Testing



Specific to:

Lexus ES250 1990-1991

Lexus ES300 1992-1996

  1. Inspect the charging circuit without load. If a battery/alternator tester is available, connect the tester to the charging circuit as per manufacturer-s instructions. If a tester is not available, connect a voltmeter and ammeter to the charging circuit as follows:
    1. Disconnect the wire from terminal B of the alternator and connect it to the negative probe of the ammeter.
    2.  
    3. Connect the positive probe of the ammeter to terminal B of the alternator.
    4.  
    5. Connect the positive probe of the voltmeter to terminal B of the alternator.
    6.  
    7. Ground the negative probe of the voltmeter.

      Click image to see an enlarged view

      Fig. Inspect the charging circuit without load

    8.  

  2.  
  3. Check the charging circuit as follows:
    1. With the engine running from idling to 2,000 rpm, check the reading on the ammeter and voltmeter.

      Standard amperage: 10 A or less
       
      Standard voltage at 77°F (25°C): 14-15 V
       
      Standard voltage at 239°F (115°C)): 13.5-14.3 V
       

    2.  

  4.  
  5. If the voltmeter reading is greater than standard voltage, replace the IC regulator.
  6.  
  7. If the voltmeter reading is less than standard voltage, check the IC regulator and alternator as follows:
    1. With terminal F grounded, start the engine and check the voltmeter reading of terminal B.

      Click image to see an enlarged view

      Fig. With terminal F grounded, start the engine and check the voltmeter reading of terminal B-1991 model shown, others similar



      Click image to see an enlarged view

      Fig. With terminal F grounded, start the engine and check the voltmeter reading of terminal B-1994 model shown, others similar

    2.  
    3. If the voltmeter reading is greater than standard voltage, replace the IC regulator.
    4.  
    5. If the voltmeter reading is less than standard voltage, check the alternator.
    6.  

  8.  
  9. Inspect the charging circuit with load:
    1. With the engine running at 2,000 rpm, turn on the high beam headlights and place the heater blower switch at -HI-.
    2.  
    3. Check the reading on the ammeter. Standard amperage: 30 A or more
    4.  
    5. If the ammeter reading is less than standard amperage, repair the alternator. With the battery fully charged, the indication will sometimes be less than standard amperage.
    6.  

  10.  

Specific to:

Lexus ES300 1997-1999

  1. Inspect the charging circuit without load. If a battery/alternator tester is available, connect the tester to the charging circuit as per manufacturer-s instructions. If a tester is not available, connect a voltmeter and ammeter to the charging circuit as follows:
    1. Disconnect the wire from terminal B of the alternator and connect it to the negative probe of the ammeter.
    2.  
    3. Connect the positive tester probe of the ammeter to terminal B of the alternator.
    4.  
    5. Connect the positive tester probe of the voltmeter to terminal B of the alternator.
    6.  
    7. Ground the negative tester probe of the voltmeter.

      Click image to see an enlarged view

      Fig. Inspect the charging circuit without load

    8.  

  2.  
  3. Check the charging circuit as follows:
    1. With the engine running from idling to 2,000 rpm, check the reading on the ammeter and voltmeter.

      Standard amperage: 10 A or less
       
      Standard voltage: 13.2-14.8 V
       

    2.  

  4.  
  5. If the voltmeter reading is greater than standard voltage, replace the voltage regulator.
  6.  
  7. If the voltmeter reading is less than standard voltage, check the voltage regulator and alternator as follows:
    1. With terminal F grounded, start the engine and check the voltmeter reading of terminal B.

      Click image to see an enlarged view

      Fig. With terminal F grounded, start the engine and check the voltmeter reading of terminal B

    2.  
    3. If the voltmeter reading is greater than standard voltage, replace the voltage regulator.
    4.  
    5. If the voltmeter reading is less than standard voltage, check the alternator.
    6.  

  8.  
  9. Inspect the charging circuit with load:
    1. With the engine running at 2,000 rpm, turn on the high beam headlights and place the heater blower switch at -HI-.
    2.  
    3. Check the reading on the ammeter. Standard amperage: 30 A or more
    4.  
    5. If the ammeter reading is less than standard amperage, repair the alternator. With the battery fully charged, the indication will sometimes be less than standard amperage.
    6.  

  10.  

 
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