it is possible, but i wouldn't recommend it. if you want to tap into a wire, locate a switched wire somewhere under the dash and use a t-tap to splice into it. these can be purchase at most car audio stores or electronics store. i think i even saw them at walmart. as for making your 2nd power plug turn off, maybe. the fuse panel in my car allows for constant on or switched ignition on depending upon where the fuse is plugged in at. check with your owners manual to verify this is not an option for you. hope this helps. good luck...
--rudy--
--rudy--