2003 GMC Sierra 1500 Pickup Owner's Manual - Page 94

To replace the battery in the keyless entry transmitter do the following: 1. Insert a dime, or similar object, in the slot between the covers of the transmitter housing near the key ring hole. Remove the bottom by twisting the dime. 2. Remove and replace the battery with a three-volt CR2032 or equivalent battery, positive (+) side up. 3. Align the covers and snap them together. 4. Resynchronize the transmitter. 5. Check the operation of the transmitter. 2-7