Factory Wiring Harness - Prewired options?
 

Okay so I've searched up a bit and can't find a definite answer via Googling the site or anything. I'm looking to do an engine swap into a cleaner (less rusty) RX8 and the example I pick up may be a higher trim than mine. I have a base (Touring? The trim levels are a mystery to me) 2004 model with cloth seats, no DSC, no sunroof etc. If I pick up a GT or whatever with the leather heated seats and sunroof, will my wiring harness have the plugs to just plug and play or will I have to wire functionality to them? I know I have fuses for options I don't have, and I also have plugs for fog lights I don't have. My 96 Celica (FWIW) also came prewired for options it didn't have. Just switches and such were needed.

TL,DR; are RX-8s prewired for options they don't have? Or is it only certain years? Only certain features? Please advise.

Engine harnesses are basically the same ...so you shouldn't have issues with swapping the engine from one car to another. Series 1 to Series 1 anyway. The Series 2 cars are vastly different so more complex

Right. I'm more concerned with the extra options and if there's extra work involved for me when this goes down though.

What else are you going to swap? If you are just swapping engines the rest will be the same as the car you are using to swap your motor into.

Aside from the engine and possibly transmission, nothing. But, my vehicle does not have the extra options - sunroof, seat heaters, etc. - so I don't know if my harness that I may have to move in (if I don't end up with another manual) has the plugs for those options already and they're just tucked away, or if it just plain doesn't have them.

The options are with the car....if you swap the motor in the engine harness is the same if both are Series 1 you will get the options in the NEW chassis

Your engine harness could give 2 shits whether you have leather seats or a sunroof ;)