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How to remove alternator on 2002 VW jetta?

Alternator



Removal & Installation





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Fig. Location of the alternator bolts on a 1994 Jetta 2.0L, 8 valve model

Before purchasing a replacement alternator, read the specification plate on the housing. The number 14V will appear to indicate maximum voltage rating. On the same line will be two more digits followed by the letter A . This is the maximum amperage output. Be sure to purchase an alternator with the same rating. The regulator can be replaced without removing the alternator.

Before purchasing a replacement alternator, read the specification plate on the housing. The number 14V will appear to indicate maximum voltage rating. On the same line will be two more digits followed by the letter A . This is the maximum amperage output. Be sure to purchase an alternator with the same rating. The regulator can be replaced without removing the alternator.

  1. Disconnect the negative battery cable.
  2. Remove the engine undercover, if equipped.
  3. Disconnect the wiring from the alternator. If necessary, mark the wires with tape or other means to ensure they are connected properly upon installation.
  4. Loosen the belt tension, and remove the drive belt from the alternator.
  5. Remove the alternator adjustment bolt, followed by the pivot bolts.
  6. Carefully lift the alternator from the bracket.

To install:

  1. Hold the alternator in position on the mounting bracket, and install the pivot bolt. On later engines with automatic belt tensioners, install the upper mounting bolt.
  2. Install (but do not tighten) the alternator adjustment bolt (earlier models only).
  3. Place the alternator drive belt on the pulley.
  4. Adjust belt tension and tighten the mounting and adjustment bolts to 18 ft. lbs. (25 Nm).
  5. Connect the wiring to the alternator. If tape was used to identify the wires, make sure it is removed once the wires are connected.
  6. Install the engine undercover, if equipped.
  7. Connect the negative battery cable.



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Fig. Alternator mounting detail-2.0L engines



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Fig. Alternator belt mounting detail-VR6 engines



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Fig. Alternator mounting detail-6 cylinder engines (except VR6 and Passat)



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Fig. Alternator mounting detail-6 cylinder engine (Passat)



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Fig. Alternator mounting detail-V8 engine (Passat)

  1. Disconnect the negative battery cable.
  2. Disconnect the wiring from the alternator. If necessary, mark the wires with tape or other means to ensure they are connected properly upon installation.
  3. Loosen the belt tension, and remove the drive belt from the alternator. On VR6 (AAA) engines only, remove the belt tensioner from the cylinder head.
  4. Remove the alternator adjustment bolt, followed by the pivot bolts.
  5. Carefully lift the alternator from the bracket.

To install:

  1. Hold the alternator in position on the mounting bracket, and install the pivot bolt. On later engines with automatic belt tensioners, install the upper mounting bolt.
  2. Install (but do not tighten) the alternator adjustment bolt (earlier models only).
  3. Place the alternator drive belt on the pulley.
  4. Adjust belt tension and tighten the mounting and adjustment bolts as necessary.
  5. Connect the wiring to the alternator. If tape was used to identify the wires, make sure it is removed once the wires are connected.
  6. Connect the negative battery cable.

Before purchasing a replacement alternator, read the specification plate on the housing. The number '14V' will appear to indicate maximum voltage rating. On the same line will be 2 more digits followed by the letter 'A'. This is the maximum amperage output. Be sure to purchase an alternator with the same rating. If the back of the alternator is readily accessible, the voltage regulator can be replaced without removing the alternator.

  1. Note the radio security code and disconnect the negative battery cable.
  2. If additional work space is needed, on A4 and 1998-00 Passat models, place the lock carrier in the Service Position. For additional information, please refer to the following topic(s): Body and Trim, Lock Carrier, Service Position.
  3. Disconnect the wiring from the alternator. If necessary, mark the wires with tape or other means to ensure they are connected properly upon installation.
  4. If equipped, remove the cooling ducts and shroud as necessary.
  5. Loosen the belt tension, and remove the drive belt from the alternator. For additional information, please refer to the following topic(s): General Information and Maintenance, Belts.
  6. If necessary, remove the belt tensioner.
  7. If equipped, remove the alternator adjustment bolt.
  8. Remove the mounting/pivot bolt(s).
  9. Carefully lift the alternator from the bracket.

To install:

  1. Hold the alternator in position on the mounting bracket, and install the mounting/pivot bolt(s).
  2. If equipped, install (but Do NOT tighten) the alternator adjustment bolt.
  3. Place the alternator drive belt on the pulley.
  4. Adjust belt tension and tighten the mounting and adjustment bolts as necessary. For additional information, please refer to the following topic(s): General Information and Maintenance, Belts
  5. Connect the wiring to the alternator. If tape was used to identify the wires, make sure it is removed once the wires are connected.
  6. Connect the negative battery cable and enter the radio security code.



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Fig. Location of the alternator bolts on the 2.0L ABA engine



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Fig. Alternator mounting detail-2.0L engines



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Fig. The 2.8L V6 alternator, regulator and their mounting components



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Fig. Use Tool No. 3310 or its equivalent to remove the alternator drive pulley on 1.8L and 2.8L engines



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Fig. Note the alternator drive belt's installation direction before removal. Install the belt in the same direction



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Fig. The 1.8L alternator is hard mounted to the front of the engine

All Others


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Fig. Alternator mounting detail-2.0L engines



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Fig. Alternator belt routing-all except VR6, with power steering, no A/C



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Fig. Alternator belt mounting detail-1993-99 diesel engines



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Fig. Diesel engine belt alternator belt routing



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Fig. Alternator belt mounting detail-1994-99 VR6 engines

  1. Disconnect the negative battery cable.
  2. Disconnect the wiring from the alternator. If necessary, mark the wires with tape or other means to ensure they are connected properly upon installation.
  3. Loosen the belt tension, and remove the drive belt from the alternator. On VR6 (AAA) engines only, remove the belt tensioner from the cylinder head.
  4. Remove the alternator adjustment bolt, followed by the pivot bolts.
  5. Carefully lift the alternator from the bracket.

To install:

  1. Hold the alternator in position on the mounting bracket, and install the pivot bolt. On later engines with automatic belt tensioners, install the upper mounting bolt.
  2. Install (but do not tighten) the alternator adjustment bolt (earlier models only).
  3. Place the alternator drive belt on the pulley.
  4. Adjust belt tension and tighten the mounting and adjustment bolts as necessary.
  5. Connect the wiring to the alternator. If tape was used to identify the wires, make sure it is removed once the wires are connected.
  6. Connect the negative battery cable.

Diesel Engine
  1. Disconnect the negative battery cable.
  2. Remove the engine undercover, if equipped.
  3. Disconnect the wiring from the alternator. If necessary, mark the wires with tape or other means to ensure they are connected properly upon installation.
  4. Loosen the belt tension, and remove the drive belt from the alternator.
  5. Remove the alternator adjustment bolt, followed by the pivot bolts.
  6. Carefully lift the alternator from the bracket.

To install:

  1. Hold the alternator in position on the mounting bracket, and install the pivot bolt. On later engines with automatic belt tensioners, install the upper mounting bolt.
  2. Install (but do not tighten) the alternator adjustment bolt (earlier models only).
  3. Place the alternator drive belt on the pulley.
  4. Adjust belt tension and tighten the mounting and adjustment bolts to 18 ft. lbs. (25 Nm).
  5. Connect the wiring to the alternator. If tape was used to identify the wires, make sure it is removed once the wires are connected.
  6. Install the engine undercover, if equipped.
  7. Connect the negative battery cable.

Gasoline Engines (Except 2.5L)

Before purchasing a replacement alternator, read the specification plate on the housing. The number 14V will appear to indicate maximum voltage rating. On the same line will be two more digits followed by the letter A . This is the maximum amperage output. Be sure to purchase an alternator with the same rating. The regulator can be replaced without removing the alternator.

  1. Before servicing the vehicle, refer to the Precautions Section.
  2. Disconnect the negative battery cable.
  3. Disconnect the wiring from the alternator. If necessary, mark the wires with tape or other means to ensure they are connected properly upon installation.
  4. Loosen the belt tension, and remove the drive belt from the alternator.
  5. Remove the alternator adjustment bolt, followed by the pivot bolts.
  6. Carefully lift the alternator from the bracket.

    Click image to see an enlarged view

    Fig. Alternator mounting detail-2.0L engines



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    Fig. Alternator belt mounting detail-VR6 engines



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    Fig. Alternator mounting detail-6 cylinder engines (except VR6 and Passat)



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    Fig. Alternator mounting detail-6 cylinder engine (Passat)



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    Fig. Alternator mounting detail-V8 engine (Passat)


To install:

  1. Hold the alternator in position on the mounting bracket, and install the pivot bolt. On later engines with automatic belt tensioners, install the upper mounting bolt.
  2. Install (but do not tighten) the alternator adjustment bolt (earlier models only).
  3. Place the alternator drive belt on the pulley.
  4. Adjust belt tension and tighten the mounting and adjustment bolts as necessary.
  5. Connect the wiring to the alternator. If tape was used to identify the wires, make sure it is removed once the wires are connected.
  6. Connect the negative battery cable.


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Diagnosis & Testing





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Fig. Many VW alternators are similar to this BOSCH unit



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Fig. Remove the connections from the rear of the alternator



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Fig. The A4 and Passat alternators are similar to this BOSCH unit



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Fig. Remove the connections from the rear of the alternator

Alternator 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. Increase and hold engine speed to 2000 rpm.
  3. Measure the voltage reading at the battery.
  4. 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.

Alternator No-Load Test
  1. 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.

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

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

Alternator Output Test


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Fig. Typical charging system output voltage test connections



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Fig. VAT-40 charging system tester. Similar testers are available that perform as well

Most automotive repair facilities purchase specialized test equipment to check a vehicle's charging system. The test equipment is expensive, however it is fast and easy to use and able to pinpoint the cause of the problem. This type of test equipment is a good investment for a repair shop, however an alternator can be checked with the use of a reasonably priced volt-ohm (VOM) meter. For additional information, please refer to the following topic(s): General Information and Maintenance, Tools and Equipment, Chassis Electrical.

A volt/amp tester, such as the VAT-40, or an equivalent, which is equipped with a battery load control (carbon pile rheostat), full field tester and an inductive-type pickup clamp (ammeter probe) can be used to test an alternator's diodes, amperage and voltage output following the directions supplied with the tester.

This information is useful for someone who may take it upon himself or herself to open up an alternator and replace the defective internal part. Almost all alternators used in today's vehicles have internal voltage regulators. Thus when replacing the alternator the voltage regulator no longer must be purchased separately. Because the voltage regulators have no moving parts and are electronically controlled, the only wear related item found in an alternator would be the brushes. More often than not, the alternator brushes are part of the voltage regulator, so in order to replace the brushes, the voltage regulator must be replaced.

The only drawback is that at times the cost of the voltage regulator/brush assembly may be almost as expensive as the alternator itself. Therefore it makes more sense to replace the alternator assembly rather than just one failed component. One common symptom of a failed voltage regulator/brush assembly is that the battery warning light does not operate when the ignition switch is first turned to the ON position without the engine being started. The battery must be disconnected and the alternator removed to replace the voltage regulator.

To test the voltage output of the alternator, use a VOM meter capable or reading at least 20 volts DC and proceed as follows:

  1. Before starting the test, make sure the battery is in good condition and is fully charged. Check the conditions of the battery cables.
  2. Perform the voltage drop test to ensure clean and tight alternator/battery electrical connections.
  3. Be sure the alternator drive belt is properly tensioned. For additional information on drive belt tension, please refer to the following topic(s): General Information and Maintenance.
  4. Set the parking brake, and then place the transmission in Park or Neutral.
  5. Start the engine and let it run until it reaches normal operating temperature.
  6. Connect the VOM meter to the battery following the proper polarity for the leads. Connect the positive lead to the positive terminal of the battery and attach the negative lead of the VOM meter to the negative terminal of the battery or a known good ground on the vehicle.
  7. Raise the engine speed to 1,500 rpm and check the voltage. The voltage should be 13.5-14.2 Volts. If the voltage is not within specification replace the alternator.


NOTE
If the voltage exceeds 14.2 Volts the battery could be damaged. Higher than recommended charging system voltages can warp the battery casing, boil the fluid out of the battery, and warp the internal plates. If battery damage has occurred, neutralize the battery mounting area with a 50 / 50 solution of baking soda and water, then replace the battery.

Voltage Drop Test

NOTE
These tests will show the amount of voltage drop across the alternator output wire from the alternator output ( B+ ) terminal to the battery positive post. They will also show the amount of voltage drop from the ground ( - ) terminal on the alternator.

A voltmeter with a 0-18-volt DC scale should be used for these tests. By repositioning the voltmeter test leads, the point of high resistance (voltage drop) can easily be found. Test points on the alternator can be reached by either removing the air cleaner housing or below by raising the vehicle.

  1. Before starting the test, make sure the battery is in good condition and is fully charged. Check the conditions of the battery cables.
  2. Start the engine, let it warm up to normal operating temperatures, then turn the engine OFF .
  3. Connect an engine tachometer, following the manufacturer's directions.
  4. Make sure the parking brake is fully engaged.
  5. Start the engine, then place the blower on HIGH, and turn on the high beam headlamps and interior lamps.
  6. Bring the engine speed up to 2,400 rpm and hold it there.
  7. To test the ground ( - ) circuitry, perform the following:
    1. Touch the negative lead of the voltmeter directly to the positive battery terminal.
    2. Touch the positive lead of the voltmeter to the B+ output terminal stud on the alternator (NOT the terminal mounting nut). The voltage should be no higher than 0.6 volts. If the voltage is higher than 0.6 volts, touch the test lead to the terminal mounting stud nut, and then to the wiring connector. If the voltage is now below 0.6 volts, look for dirty, loose or poor connections at this point. A voltage drop test may be performed at each ground ( - ) connection in the circuit to locate the excessive resistance.

  8. To test the positive ( + ) circuitry, perform the following:
    1. Touch the positive lead of the voltmeter directly to the negative battery terminal.
    2. Touch the negative lead of the voltmeter to the ground terminal stud on the alternator case (NOT the terminal mounting nut). The voltage should be no higher than 0.3 volts. If the voltage is higher than 0.3 volts, touch the test lead to the terminal mounting stud nut, and then to the wiring connector. If the voltage is now below 0.3 volts, look for dirty, loose or poor connections at this point. A voltage drop test may be performed at each positive ( + ) connection in the circuit to locate the excessive resistance.

  9. This test can also be performed between the alternator case and the engine. If the test voltage is higher than 0.3 volts, check for corrosion at the alternator mounting points or loose alternator mounting.

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. Using a Digital Volt/Ohm Meter (DVOM) set to volts DC, probe across the battery terminals.
  3. Measure the battery voltage.
  4. Write down the voltage reading and proceed to the next test.

Precautions





Always disconnect the battery cables when removing or disconnecting the alternator.
Disconnect the battery cables before using a fast charger. The charger has a tendency to force current "backwards" through the diodes and burn them out.
Never disconnect the battery cables or alternator while the engine is running.
Do not attempt to "polarize" an alternator.
Never reverse battery connections. Do not connect the battery in series with another without disconnecting it from the charging system.
When jump starting from another vehicle, try to avoid running the other car's engine. Do not allow alternators from two different charging systems to be running and connected with jumper cables.
Do not ground the alternator output terminal.
Disconnect the battery cables before using an electric arc welder on the car.

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



ALWAYS observe proper polarity of the battery connections. Use extreme care when jump starting the car. Reversing the battery connections may cause the battery to explode, or result in damage to the one-way rectifiers.
ALWAYS remove the battery or, at least, disconnect the cables while charging to avoid damaging the alternator.
ALWAYS match and/or consider the polarity of the battery, alternator and regulator before making any electrical connections within the system.
ALWAYS disconnect the battery ground terminal while repairing or replacing any electrical components.
NEVER use a fast battery charger to jump-start a vehicle with a dead battery.
NEVER attempt to polarize an alternator.
NEVER use test lights of more than 12 volts when checking diode continuity.
NEVER ground or short out the alternator or regulator terminals.
NEVER separate the alternator on an open circuit. Make sure all connections within the circuit are clean and tight.
NEVER use arc welding equipment on the car with the battery cable, control modules or alternator connected.
NEVER operate the alternator with any of its or the battery's lead wires disconnected.
NEVER subject the alternator to excessive heat or dampness (for instance, steam cleaning the engine).
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.
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