Plastic Starter Switch module on the Ignition switch has gone bad. It shorts out when you turn the key to the START position. You'll need to replace the switch module. See attached link for a picture of what it looks like...
Beck Arnley 201-1915 Starter Switch | Auto Parts Warehouse
It's a known problem on S14's. The modules go bad after a while. I've seen it happen to several S14's over the years.
Hope this helps...
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