This module walks through a series of real-world diagnostic case studies focused on ignition systems, sensor signals, and fuel injection, using scope waveforms and action/reaction testing to reach accurate conclusions efficiently.

Cases covered include:

• Timing belt failure identified through cam/crank relationship analysis on a 96 Concord 3.5
• Primary ignition failure analysis revealing multiple simultaneous faults on a distributor ignition system
• VSS signal diagnostics on two vehicles, including a module-loading issue pulling down a shared signal line
• Ford DPFE/EGR system diagnosis and a practical hands-on testing method for quickly isolating flow and component faults
• A low system voltage condition on a 95 S10 4.3 Vortec causing VCM shutdown, with a reminder that cranking rhythm alone doesn't confirm adequate voltage
• Magneto resistive crank sensor operation and how it differs from a standard hall effect sensor
• Ignition control module failure on a 91 Audi 100 traced through scope analysis of distributor reference vs. power transistor command
• An unexpected cross-driver interaction caused by a shorted injector on a Geo Storm
• C3I ignition diagnosis on an 86 Olds 98 using crank sensor input vs. reference output as an action/reaction test

A recurring theme throughout is the importance of checking system voltages, trusting scope data over scanner PIDs, and following a disciplined action/reaction approach regardless of the system being tested.