This guide walks through common causes of a no-spark condition when using MSD, Mallory, HyperSpark, or ACCEL capacitive discharge ignition systems. Start with the basics—verify you have solid power and ground at the ignition box, and confirm 12 volts is present at the switched power wire during both key-on and cranking. From there, inspect wiring, connectors, and fuses, including any inline additions. Unlike traditional inductive systems, these ignition boxes discharge high voltage through a capacitor, so standard voltage checks at the coil won’t apply. Additional causes of no spark can include worn distributor components, bad coil wires, or mechanical issues inside the distributor such as gear failure or a sheared pin.

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Once those areas are confirmed, you can test the ignition box directly using either the white wire (for points or amplified distributors) or the magnetic pickup connector (green/violet wires). By simulating a trigger signal—either grounding and releasing the white wire or jumping the magnetic pickup terminals—you should see spark from the coil wire. If spark appears, the box is functioning correctly; if not, isolate the issue by swapping in a known good coil. Still no spark typically indicates a faulty ignition box that may require service. Watch the full video for a step-by-step demonstration and learn how to confidently diagnose ignition issues in your setup.