GMC 2007 Yukon XL Owner's Manual page 116

Battery Replacement
Under normal use, the battery in your RKE
transmitter should last about four years.
You can tell the battery is weak if the transmitter
will not work at the normal range in any location.
If you have to get close to your vehicle before
the transmitter works, it is probably time to change
the battery.
The REPLACE BATTERY IN REMOTE KEY
message in the vehicle's DIC will display if the
RKE transmitter battery is low. See "REPLACE
BATTERY IN REMOTE KEY" under DIC Warnings
and Messages on page 254 for additional
information.
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.
116
To replace the battery in the RKE transmitter do
the following:
1. Use a flat object with a thin edge into the
notch, located below the trunk release
button, and separate the bottom half from the
top half of the transmitter.
2. Remove the old battery, but do not use a
metal object to do this.