Two days ago , the power door lock ( on the passenger side door ) of my wife's 2000 Impala LS stopped working . The lock can still be operated manually but the main switch ( on the driver's door ) as well as the single switch ( on the passenger door ) does not activate the locking mechanism . Also , the key fob unlocking and locking function does not have any effect on the mentioned lock's operation . All the other locks work normally . Is this a relay problem or ...what ? Anyone have a similar experience ?