I know this is an old thread but my cousin was given a stereo with a detachable face that was glitchy as. I cleaned all the contacts on the back of the faceplate and on the contacts up front of the head unit and he got back all functions and display (the guy he bought it off for $20 wanted it back after I fixed it - some people...) I used some cotton tips and a little metal polish on the copper contacts and it sorted out the connection issues.