Cher The Lights Are On ... Cause Sonny's Home

10/1/2013 6:04 AM PDT

Cher -- The Lights Are On 'Cause Sonny's Ghost Is Home

is standing firm that Sonny Bono is inhabiting her Malibu mansion.

We got Cher at LAX yesterday ... and asked her if she was sure Sonny was behind the mysterious light flickering.  Cher was certain the mercurial Sonny was hitting the switch.

And there's a reason she KNOWS it's not some other ghost.

So we gotta ask ...