This module uses a series of real-world vehicle case studies to reinforce the core principle of ignition coil diagnostics: validating primary drive by confirming current level and clean cutoff. Tom walks through failures on vehicles ranging from an '86 Golf to a '93 Jeep Grand Cherokee, demonstrating how this two-factor approach consistently and efficiently identifies whether the fault lies in the coil or the primary drive circuit.

Key topics covered include:

• Why a delay in primary current cutoff reduces secondary output, and how to identify the cause (modules, fuel pump relays, aftermarket add-ons, etc.)
• How to use an amp probe and scope together to validate primary drive, including single-channel strategies
• Why induction ramp shape alone is unreliable for diagnosis, and the many internal and external factors that can alter its appearance
• The distinction between "gravy" information and the physics-based essentials needed to make a correct call

By the end of this module, you should have a solid understanding of why current and cutoff are the only two things required to validate primary drive, and why chasing ramp shape without that foundation leads to misdiagnosis.