Chevrolet 2003 Tahoe Owner's Manual page 96

To replace the battery in the keyless entry transmitter
do the following:
2. Remove and replace the battery with a three-volt
3. Align the covers and snap them together.
4. Resynchronize the transmitter.
5. Check the operation of the transmitter.
CR2032 or equivalent battery, positive (+) side up.
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.
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