Log In
Search suggestions

    My Vehicles

    1985 Mercedes Benz 300DT 3.0L Turbo Diesel 5cyl

    My Store

    405 N COLLEGE ST
    (479) 443-4043

    CLOSED Open at 8:00 AM

    EXTENDED! SAVE 20% ON ONLINE SHIP-TO-HOME ORDERS OF $100 OR MORE.

    Use Code: SEECLEAR

    See Details

    GM Cadillac Deville_Fleetwood_ELD_Seville 1990-1998

    Alternator

    Print

    TESTING



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

    No-Load Test
    1. Connect a tachometer to the engine.
    2.  


    CAUTION
    Ensure that the transmission is in Park and the emergency brake is set. Blocking a wheel is optional and an added safety measure.

    1. Turn off all electrical loads (radio, blower motor, wipers, etc.)
    2.  
    3. Start the engine and increase engine speed to approximately 1500 rpm.
    4.  
    5. 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.
    6.  
    7. 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.
    8.  


    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. Further testing, which is not covered by this guide, will reveal the exact component failure. 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.

    1. If the voltage is within specifications, proceed to the next test.
    2.  

    Load Test
    1. 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).
    2.  
    3. Increase and hold engine speed to 2000 rpm.
    4.  
    5. Measure the voltage reading at the battery.
    6.  
    7. 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.
    8.  


    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. Further testing, which is not covered by this guide, will reveal the exact component failure. 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.

    REMOVAL & INSTALLATION



    3.0L Engine
    1. Disconnect the battery negative cable from the battery terminal.
    2.  
    3. Remove the Pre-volume chamber.
    4.  
    5. Remove the serpentine drive belt from the generator.
    6.  
    7. Raise and safely support the vehicle securely on jackstands.
    8.  
    9. Unscrew the terminal nuts and remove the electrical leads from the generator.
    10.  
    11. Remove the generator air-cooling duct.
    12.  
    13. Remove the upper nut from the generator and AIR injection crossover pipe
    14.  
    15. Remove the lower bolt and nut.
    16.  
    17. Disconnect the generator from the engine-with the generator loose, push the upper mounting bolt out of the generator and bracket.
    18.  
    19. Lower the vehicle.
    20.  
    21. Remove the generator from the vehicle.
    22.  

    To install:

    1. Place the generator into the vehicle.
    2.  
    3. Raise and safely support the vehicle securely on jackstands.
    4.  
    5. Mount the generator to the engine-with generator loosely installed onto engine, insert the upper mounting bolt.
    6.  
    7. Install the lower bolt and nut and tighten to 30 ft. lbs. (40 Nm).
    8.  
    9. Install the upper nut to the generator and AIR injection crossover pipe, and tighten the nut to 30 ft. lbs. (40 Nm).
    10.  
    11. Install the generator air-cooling duct.
    12.  
    13. Connect the electrical leads and terminal nuts to the generator. Tighten the field coil terminal nut to 31 inch lbs. (3.5 Nm). Tighten the battery terminal nut to 71 inch lbs. (8 Nm).
    14.  
    15. Lower the vehicle and install the serpentine belt to the generator.
    16.  
    17. Install the pre-volume chamber.
    18.  
    19. Connect the negative battery cable.
    20.  

    4.6L Engine Except Seville
    1. Disconnect the negative battery cable.
    2.  
    3. Remove the cover from the headlamps and radiator shroud.
    4.  
    5. Remove the air cleaner, if necessary.
    6.  
    7. Disconnect the left engine torque strut from the radiator support.
    8.  
    9. Disconnect the upper trans oil cooler line from the trans cooler.
    10.  
    11. Remove the right cooling fan and the left cooling fan.
    12.  
    13. Remove the serpentine belt from the generator pulley.
    14.  
    15. Remove the bolt from the front top of the generator, and the bolt from the lower front of the generator.
    16.  
    17. Detach the harness connector and output cable from the generator.
    18.  


    NOTE
    The bolt nearest the exhaust manifold cannot be removed from the bracket but can be backed out to allow for removal of the generator.

    1. Removal the A/C splash shield from the cradle, and the access panel from the bottom side of the radiator support.
    2.  
    3. Disconnect the engine harness from the cradle.
    4.  


    NOTE
    The generator can be moved out away from the engine and removed from the bottom side of the engine compartment.

    1. Connect the negative battery cable.
    2.  



    Click image to see an enlarged view

    Fig. Alternator mounting-4.6L Northstar engine



    Click image to see an enlarged view

    Fig. Component view of the generator and electrical connector



    Click image to see an enlarged view

    Fig. Remove the top retaining bolt for the alternator



    Click image to see an enlarged view

    Fig. Loosen the lower mounting bolt



    Click image to see an enlarged view

    Fig. Remove the protective cap to gain access to the electrical connectors



    Click image to see an enlarged view

    Fig. Removing the retaining nut that holds the battery cable to the alternator



    Click image to see an enlarged view

    Fig. Back the bolt on the rear of the alternator out as far as possible and the unit can be removed from the mounting



    Click image to see an enlarged view

    Fig. Pull the lower mounting bolt from the generator



    Click image to see an enlarged view

    Fig. With the cable removed, attempt to bring the alternator through the allotted opening



    Click image to see an enlarged view

    Fig. Rotate the generator, if it aids the removal



    Click image to see an enlarged view

    Fig. Rotating the generator nose down . . .



    Click image to see an enlarged view

    Fig. . . . seemed to be the only way to extract it from the mounting

    To install:

    1. Install the generator to mounting with the two bolts to the rear of the generator. Hand tighten the bolts.
    2.  
    3. Connect the engine harness clip to the cradle.
    4.  
    5. Install the access panel to the lower radiator support. Install the A/C splash shield to the cradle.
    6.  
    7. Attach the harness connector and output cable to the generator.
    8.  
    9. Tighten the rear mounting bolts to 36 ft. lbs. (47 Nm). The output cable to 15 ft. lbs. (20 Nm).
    10.  
    11. Install the bolt to the lower front of the generator and tighten to 36 ft. lbs. (47 Nm). Install the bolt to the top front of the generator and tighten to 36 ft. lbs. (47 Nm).
    12.  
    13. Rotate the drive belt tensioner and install the drive belt around the generator pulley. Inspect for correct alignment of the belt with all the accessory pulleys.
    14.  
    15. Install the left cooling fan, and then the right.
    16.  
    17. Attach the upper trans oil cooler line to the trans cooler.
    18.  
    19. Install the left engine torque strut.
    20.  
    21. If the air cleaner was removed, install it now.
    22.  
    23. Replace the cover from the headlamps and radiator shroud.
    24.  
    25. Connect the negative battery cable.
    26.  

    Seville With 4.6L Engine

    On some models, the generator is water-cooled. When this is the case, the repair procedure is as follows:

    1. Disconnect the negative battery cable.
    2.  
    3. Remove the accessory drive belt.
    4.  
    5. Drain and recycle the engine coolant.
    6.  
    7. Remove the radiator.
    8.  


    NOTE
    If your vehicle is equipped with air conditioning, refer to the information regarding the implications of servicing your A/C system yourself. Only an MVAC-trained, EPA-certified, automotive technician should service the A/C system or its components.

    1. Remove the A/C condenser.
    2.  
    3. Raise and safely support the vehicle securely.
    4.  
    5. Disconnect the coolant inlet and outlet hoses from the generator.
    6.  
    7. Detach the electrical connections from the generator. The regulator, the battery output, and the heated windshield (if equipped) will need to be unplugged.
    8.  
    9. Remove the generator fasteners from the generator.
    10.  
    11. Remove the generator from the vehicle.
    12.  

    To install:



    Click image to see an enlarged view

    Fig. This shows the coolant outlet hose being removed, signified by the "1" in the diagram

    1. Attach the generator to the engine and tighten the fasteners to 37 ft. lbs. (50 Nm).
    2.  
    3. Attach the electrical connections for the regulator, battery output, and the heated windshield.
    4.  
    5. Tighten the battery output cable to 15 ft. lbs. (20 Nm).
    6.  
    7. Reconnect the coolant inlet and outlet hoses to the generator.
    8.  
    9. Lower the vehicle.
    10.  
    11. Install the A/C condenser.
    12.  
    13. Install the radiator.
    14.  
    15. Install the accessory drive belt.
    16.  

    4.5L and 4.9L Engine
    1. Disconnect the negative battery cable.
    2.  
    3. Remove the generator harness connector and battery charging wire on the back of the generator. Heated windshield 3-phase connector and clip if equipped.
    4.  
    5. Release the tension from the drive belt land remove the belt from the generator pulley. Do not remove the belt from any other component pulleys.
    6.  
    7. Remove the volts, ABS ground strap, and generator from the vehicle.
    8.  



    Click image to see an enlarged view

    Fig. Alternator mounting-early models with 4.5L and 4.9L engines



    Click image to see an enlarged view

    Fig. Alternator mounting-later models with 4.5L and 4.9L engines

    To install:

    1. Install the generator and ground strap to the mounting bracket with bolts tightened to 20 ft. lbs. (27 Nm).
    2.  
    3. Raise the drive belt tensioner. Position the drive belt over the generator pulley and release the tensioner.
    4.  
    5. Attach the generator harness connector and battery-charging wire to the generator output stud. Do not route the battery charging wire to rest against the cruise control servo. Tighten to 15 ft. lbs. (20 Nm). Do not overtighten.
    6.  
    7. Connect the negative battery cable.
    8.  

     
    AutoZone Logo