radio trouble
 

Hey guys.
I just got a 07 accord last week,and love it!
In trying to install my bazooka tube subwoofer, I took out my radio and looked for a remote wire in the preinstalled aftermarket head unit. I couldnt find one. So I decided to put in my other head unit from my old car. I cut all the wires and hooked her up, but it wouldn't work! I then reinstalled the original unit with the original wiring harness and still, no luck! I would hear it register the CD, but no display or sound. I assumed it was a faulty remote wire (I also checked the fuses), but I don't understand, because it worked perfectly before! Messing around with it, I got the display to come on when I touched the power wire to the remote wire, but then it won't turn off...
Can anyone explain this? I'm baffled, and there doesn't seem to be an explanation online.

so there was already an aftermarket head unit when you bought the car? and it didn't have a blue/white remote output wire? what make/model?

use a DMM to measure voltage at the battery and ignition wires (possible you blew a fuse cutting wires). sounds like the ignition wire doesn't have voltage but battery does (why you hear the CD spin but no display). energizing the remote output is a bad idea and can damage the HU.

what make/model is your other aftermarket? pic of the wiring in the dash?