The blue wire on the back of the HU. If that doesn't work, goto the fuse panel. Use a test light and find a fuse that gets power when the key is on and when the car is started, but doesn't when the key is off. Then wrap the remote wire around the prongs of that fuse and plug it back in.
See, I don't know how to take out my head unit. I had to reach in down by the pedals and feel my way around to install the RCA cables. Now doing the remote is the tricky part I jsut really don't want to screw up my car.