Face Plate

Im trying to install a Pioneer DEH-P6400 in my 1997 Suburban and i need to know whether it is necessary to disconnect the negative battery cable or not. I can't seem to get it off, i can get the positve one of though. If i disconnect the positive will it be just as good as disconnecting the negative or do i not need to disconnect the battery at all?

either or, removing the positive is fine.