Field Coil Open Test
WARNING: This page is about a different car, the 1998 Cadillac Seville, 1998 Cadillac Eldorado, and 1998 Cadillac DeVille. However, it is still accessible from the selected car via links, so may be relevant.
Remove armature from the frame and field assembly. Using a self-powered test light, place one lead on field lead connection and other lead on one insulated brush. See Fig 1. Test light should illuminate. If test light does not illuminate, field coil is open. Repair or replace field and frame assembly. Repeat test for each insulated brush.