Transmitter Resynchronization
WARNING: This page is about a different car, the 2004 Buick Regal and 2004 Buick Century. However, it is still accessible from the selected car via links, so may be relevant.
After the battery has been changed in the remote keyless transmitter, it will need to be resynchronized. To do this, press and hold both the LOCK and UNLOCK buttons on the remote keyless entry transmitter until one horn chirp is heard.