How do you reset the computer on a 1999 Cadillac DeVille?

To reset the computer on a 1999 Cadillac DeVille, disconnect the negative battery terminal using a wrench and leave it disconnected for about 15 minutes. This allows the computer to reset and clear any stored trouble codes. After the time has elapsed, reconnect the negative terminal and start the vehicle. This process will reset the computer, but keep in mind that it may also erase any learned driving patterns or settings.