Ignition System Testing (Siemmens 2003)
WARNING: This page does not describe the selected car, but rather 37 other vehicles, including the 2005 BMW 760i, 2004 BMW 760Li, 2003 BMW Z8, 2003 BMW Z4, and 2003 BMW X5. However, it is still accessible from the selected car via links, so may be relevant.
If there is a fault in the secondary ignition, testing should include primary ignition and evaluation of secondary oscilloscope patterns. See BASIC DIAGNOSTIC PROCEDURES article.