The alternator in a VW Passat operates various accessories in the vehicle by transmitting an electrical current while the engine is running. The alternator assembly frequently includes a voltage regulator that maintains a constant voltage level. If your headlights become dimmer while driving or your battery keeps running down, you may need to replace the alternator.
Determine which alternator your VW Passat needs. Be sure the new alternator is compatible with your Passat's engine. Models made before 1982 are equipped with a 1.3 L, 1.4 L, 1.6 L or 1.5 L diesel engine.
Look at later models of the VW Passat. Models built from 1982 to 1987 may have a 1.3 L, 1.5 L, 1.6 L, 1.8 L, 1.9 L, 2.0 L and 2.2 L gasoline engines in addition to 1.5 L, 1.6 L and 1.8 L diesel engines. Engine choices for 1988 to 1993 models include 1.6 L, 1.8 L, 1.9 L, 2.0 L and 2.8 L sizes.
Examine engines for recent models of the VW Passat. Models made from 1994 to 1997 have 1.6 L, 1.8 L, 2.0 L, 2.8 L and 2.9 L gasoline engines and a 1.9 L diesel engine. Models built from 1996 to 2000 also offer a 2.3 L gasoline engine and 2.5 L diesel engine. The 2.9 L engine was replaced with a 4.0 L engine for 2001 to 2004 models.
Look at the engines for the VW Passat made after 2005. These models may have a 1.4 L, 1.6 L, 1.8 L, 2.0 L, 3.2 L and 3.6 L engine. This model is also available with a 1.9 L and 2.0 L diesel engine.
Disconnect the negative battery cable with a socket wrench. Label the wires, if necessary, and remove the electrical wiring from the alternator.
Release the belt tension so you can remove the drive belt from the alternator. Remove the mounting bolts with a socket wrench if you have a 2.5 L engine. Otherwise, use a socket wrench to remove the adjustment bolt and then the pivot bolts for the alternator. This allows you to carefully detach the alternator from its bracket.
Install the new alternator assembly on the bracket. Install the upper mounting bolt on 2.5 L engines with a socket wrench. Otherwise, fasten the pivot bolt and loosely install the adjustment bolt. Place the drive belt on its pulley and adjust the tension. Tighten all the bolts as required.
Connect the electrical wiring as indicated by your labels and connect the negative battery cable with a socket wrench.
