how do I hook these to this? I don't even know what the larger plug is for. I was thinking this would be an easy swap. At most a bit of splicing but I figured I should ask since I can't seem to find any info on that plug.

 

Orange/black is the dash lights. Purple/white is the power...

 

so I don't need that big plug at all and I can just splice power. awesome. thanks a bunch!

 

One of the cool things to do with an old cigarette lighter (it's just 12V power and ground connections BTW) is to install a remote dash-mounted USB port for an aftermarket radio (or just as a "Charge-Only" port, since typically no one carries a separate car charger anymore). If your cigarette lighter isn't working, or you just don't need it, I'd highly recommend installing one, as they're relatively cheap and easy to install.

-Vince