How do you change a tension pulley on a 2005 Buick rendezvous?

To change the tension pulley on a 2005 Buick Rendezvous, first, disconnect the negative battery cable to ensure safety. Next, use a socket wrench to relieve tension on the serpentine belt by rotating the tensioner pulley, then remove the belt from the tension pulley. Unbolt the old tension pulley from its mount, replace it with the new one, and reattach the serpentine belt following the proper routing. Finally, reconnect the battery cable and check the installation.