2007 GMC Savana Van Owner's Manual - Page 106

Resynchronization Resynchronization may be necessary due to the security method used by this system. The transmitter does not send the same signal twice to the receiver. The receiver will not respond to a signal that has been sent previously. This prevents anyone from recording and playing back the signal from the transmitter. To resynchronize your transmitter, stand close to your vehicle and press and hold the lock and unlock buttons on the transmitter at the same time for seven seconds. The door locks should cycle to confirm synchronization. If the locks do not cycle, see your dealer for service. Battery Replacement Under normal use, the battery in your remote keyless entry transmitter should last about four years. You can tell the battery is weak if the transmitter won't work at the normal range in any location. If you have to get close to your vehicle before the transmitter works, it's probably time to change the battery. Notice: When replacing the battery, use care not to touch any of the circuitry. Static from your body transferred to these surfaces may damage the transmitter. 106