I dunno exactly how it works with the Celica, but when my dad and I installed them on my Neon, to get the blinker to work we had to splice a wire off of the front turn signal and then run it all the way back to the Mirrors
. Then, to make them power it was just unplug the power stuff from the old Mirrors
and plug them into the power stuff for the new Mirrors
. Good luck with the install!