Okay, I'd like to know what plugs into the harness that is circled below.

BONUS POINTS if you can tell me whether or not the logicon/heater controller works (specifically will the fans blow) when this is NOT connected.

 

logincon plugs in over on the other side by the steering wheel. I'm not sure, but I would guess security alarm plugs there, but don't quote me on it.

 

Seems like when I was rewiring my speakers, that's where the speaker mounted amp and all hooked up, but I might be wrong as well

 

I do know that it is NOT where the speaker plugs in...close to it, but not it. I also know where the logicon plugs in, however mine is not turning on and everything else is. I've tried a new logicon with no luck. So trying to figure out what went wrong. Thinking this big empty plug may be related.

 

definitely for the factory alarm.

 

Also, your fans will blow if you put 12V to the right color wires. Check FSM body electrical.

 

factory alarm, thats where i had to grab my arm/disarm wires for my remote start install

 

New thread for logicon issues:

https://www.rx7club.com/showthread.p...4#post11020504

 

thats not for the logicon.
The logicon connector is located at the firewall.
Pop the top dash plate off and you cab see it.
that connector is for AC.( I am pretty sure),I saw it all all my car that did NOT have A/C and it was just sitting there unplugged so I never worried about it!