Hello
On a 1986 alternator there are 2 prong type electrical terminals one is vertical the other is horizontal . In order to charge the battery does one or both of these terminals need to be connected to the battery . The threaded connection does I know that but the other 2 are a mystery . Any help will be richly rewarded with as much of anything as you want. Thanks

 

The top one should be the Black/White and is for regulation of the output. The White/Black one is dual purpose. It supplies excitation on startup and also acts as a ground signal for the idiot light relay to come on/go off.

If both are off, and the engine is rev'd over say 2 grand, the alternator will get its excitation internally from it's diode trio, and put out power to the large batt wire.

So put the small two wire plug on the alternator.

I put a jpg of the alternator circuit on this thread https://www.rx7club.com/forum/showth...ght=alternator

There is a SEARCH engine on this site up at the top. Just put altermator in there and you'll be overwhelmed with threads on alternators.