GMC 2007 Savana Van Owner's Manual page 107

To replace the battery in the keyless entry
transmitter, do the following:
1. Use an object like a coin to pry open the
transmitter.
2. Once the transmitter is separated, use an
object like a pencil to remove the old
battery. Do not use a metal object.
3. Remove and replace the battery, positive (+)
side down.
4. Snap the transmitter back together tightly to
be sure no moisture can enter.
5. Press and hold the lock and unlock buttons
on the remote keyless entry transmitter for
seven seconds to resynchronize the
transmitter.
6. Check the operation of the transmitter.
107