Cadillac 1999 Seville Owner's Manual page 62

2. Once the transmitter is separated, use a pencil (or a
similar object) to remove the old battery. Do not use
a metal object.
3. Insert the new battery as the instructions under the
cover indicate.
4. Snap the transmitter back together tightly to be sure
no moisture can enter.
5. Resynchronize the transmitter. See the instructions
that follow.
2-10
Resynchronization
Pressing the transmitter buttons numerous times
(approximately 250 times) out of the vehicle's operating
range may cause the transmitter not to work. Replacing
the battery and pressing the transmitter buttons out of
range will also cause the transmitter not to work. If only
the fuel door button works, the transmitter needs to be
resynchronized to the receiver. Do this by pressing and
holding both the lock and unlock buttons on the
transmitter for about eight seconds. You must be within
range of the vehicle.
Once the transmitter has been resynchronized, the horn
will sound and the exterior lamps will flash once. The
system should now operate properly. See your dealer for
service if your transmitter still doesn't work properly.
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