A4 & A6

WARNING: This page is about a different car, the 2000 Audi S4, 2000 Audi A6, and 2000 Audi A4. However, it is still accessible from the selected car via links, so may be relevant.

Set ohmmeter on 100x scale. Connect ohmmeter leads between generator output terminal and each 3 stator terminals, in turn. See Fig 1 . Reverse ohmmeter leads. If ohmmeter indicates continuity in only one direction, go to next step. If ohmmeter indicates continuity in both directions, replace diode assembly.
Connect ohmmeter leads between negative plate and each 3 stator terminals, in turn. Reverse ohmmeter leads. If ohmmeter indicates continuity in only one direction, go to next step. If ohmmeter indicates continuity in both directions, replace diode assembly.
Connect ohmmeter leads between Blue (D+) wire terminal and each 3 stator terminals, in turn. Reverse ohmmeter leads. If ohmmeter indicates continuity in only one direction, diode assembly is okay. If ohmmeter indicates continuity in both directions, replace diode assembly.

Fig 1: Testing Diode Assembly (Bosch 110-Amp Generator)

Courtesy of AUDI OF AMERICA, INC.