NickTRDxA

My 2005 xA with Scion security started acting up last year. Now the drivers power door won't lock/unlock at all. If I double tap the buttons on my key fob, all the other doors work fine, just not the drivers door. I can manually lock/unlock it, but no power lock action.
Anyone had this problem before and know what the issue was? I'd hate to take it in to the dealership and pay for a diagnosis if someone here has had this happen before and can tell me what part needs replaced.
Thanks in advance.