Can a 2006 Sienna automatic sliding door be made into a manual sliding door?

Yes it can. If the cables have frayed or broken you can trim them off as short as possible and then just operate it as a manual door. There is an article here that explains how to do this: http://www.shareyourrepair.com/2015/07/how-to-trim- broken-sliding-door-cables-on-2004-2010-toyota-sienna.html and if you want to repair your sliding doors there is a detailed step-by-step tutorial here: http://www.shareyourrepair.com/2014/01/how-to-replace-the- power-sliding-door-cables-2004-207-toyota-sienna-xle.html One thing I may add is that if you only trim the cables the motor will still attempt to open/close the door if you don't open up the door and disconnect the motor's electrical wiring connector, which is covered in the second link.