Field Coil Test
WARNING: This page is about a different car, the 2004 Lexus SC 430, 2003 Lexus SC 430, and 2002 Lexus SC 430. However, it is still accessible from the selected car via links, so may be relevant.
Using ohmmeter, check for continuity between starter solenoid lead and field coil brush lead. If continuity does not exist, replace field frame. Using ohmmeter, check for continuity between field coil end and field frame. If continuity exists, repair or replace field frame.