I have included 2 files, one setup is the diffuse pass, and the other is an Ambient Occlusion Pass.
The files are setup to render as is, but the Ambient occlusion is simple to reproduce into the diffuse scene file if you wish to combine them into the same file.
If you are having trouble opening this in an earlier version of Maya, simply click the option box next to open in the file menu of your version of maya, and tick the check box that says 'ignore version' and it should open fine.
If that doesn't work, I've included an MA file. you can open it in a text editor and delete anything portion that says 2009, and it should definitely work. But the above should be just fine.