I want to put a additional 12v plug under the dash on the left side. I need help finding a 12v keyed hot under the dash.

 

what you trying to run? depending if it needs a dedicated 12v,
why not just splice it into the existing 12v cig lighter

i made mine into a dual cig lighter outlet - 1 on the driver side and one on the passanger side in my car - never had any issues with it

 

if you ever plan on using both outlets at the same time it would be much better to run a new feed from the battery or a bat slot in the fuse box with a in line fuse for saftey

 

I ran 3 new lines direct from battery positive. Put a fuse in line, got the fuse holders ready to wire in at local Cdn Tire Auto Hdwr store. Ran e thru hole in firewall by brake booster near where the throttle cable comes out, just above the fuse box. Used 10ga wire. Terminated on a terminal block, also from local auto hardware. Now lots of power options available for accessories and can be fused seperately.