Code P0700 and P0740

When ever I turned off my van, Transmission makes a wired sound, Its like even though engine turns off as soon as I trun the key to off, but transmission takes couple of seconds more to shut off. Any body, have any idea why is this. I just bought the van a month ago and have only 60K on it.

Thanks in advance

code 700: The automatic transmission computer or Aisin computer has a problem - ask it what's going on. I don't know

code: 740 The engine's running faster than it should for these speeds, so I think the torque convertor clutch lock-up system is bad