Color me skeptical, but I think you must have fixed something else by accident while fixing that wire. The Crane system couldn't care less if the distributor plate is grounded, 12V+, or anything else. No electrical connection to the distributor at all, just mechanically hooked to the plate.

It's optical, perhaps the little LED or the sensor was dusted over. perhaps the chopper wheel slipped backwards on the rotor. Perhaps that multiconnector between the Crane sensor and control box had an iffy connection. But not that ground wire.

Unless I've totally misunderstood something basic about the way the Crane system works. But I've had mine working laid across the living room floor with no distributor at all (tinkering with it and trying to get it to interact with my Megasquirt controller) and the sensor is completely independent. When it can beam light across the gap it's "on", when it can't it's "off".
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I'm JohnMc, and I approved this message.