This depends on where you have constant spark. Because you are saying there is constant "spark" then I assume this is on the coil wire to the distributor. However if you are saying you have constant voltage on one of the wires coming into the coil then this is a different story. You should have constant voltage on the B+ wire at the coil which is actually in two locations. So we would need to clarify this.
I attached the detail about how this ignition system works for your review. It explains how the system operates and what turns the spark on and off. The PCM is the ultimate control but the vane switch could be the issue as well. However, if the spark is constant from the coil to the distributor then the coil is most likely the issue.
Please let us know if there are questions or what you find.
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Monday, May 31st, 2021 AT 12:45 PM