* Consult your owner's manual: This is the best resource for the precise location.
* Look for a large, rectangular black box: The PCM is usually a fairly large electronic module.
* Check online forums and repair manuals: Searching for "2000 Buick LeSabre PCM location" on forums dedicated to Buick or automotive repair can yield helpful pictures and descriptions.
Remember to disconnect the negative battery terminal before attempting to access or work on the PCM.