Check for continuity between the slip rings (C).

Check that there is no continuity between the slip rings and the rotor (B) or rotor shaft (A).

If the rotor fails either continuity checks, replace the alternator.

Check that there is continuity between each pair of leads (A).

Check that there is no continuity between each lead and the coil core.

If the coil fails either continuity checks, replace the alternator.