HEI Stock dist shut down

The signal generated at the pickup is generated by a change in the magnetic circuit. The pickup has a coil and a permanent magnet, the reluctor draws magnetic flux away. As the tooth nears the pickup, the flux becomes negative, when on the tooth the flux is constant, the voltage is zero, when pulling away it become positive, that is the trigger point. The trigger point threshold may vary with supply voltage, so when powered off the ignition may be triggered. The dip in voltage results a false trigger, it may not be consistent. Remember the HEI design is analog and originated in the mid 70's, it is far from perfect, but still an improvement over the mopar box. Some may not feel comfortable with that.