Abstract: An apparatus for determining component fault conditions associated with a capacitive discharge ignition system for an internal combustion engine includes a number of AC coupling circuits connected to a spark detection circuit, wherein the combination is responsive to a corresponding number of primary coil voltage signals to produce digital pulses indicative of reflected spark events from the various secondary coils to the respective primary coils of the ignition system. A number of level shifting circuits are also included and provide a pulse width circuit with a corresponding number of level-shifted primary coil voltage signals. A pulse width circuit is responsive to the number of level-shifted primary coil voltage signals to produce appropriate digital pulses timed to match the non-zero voltage times of the various primary coil voltage signals.