diagram Mercury Mountaineer 1999 Owner's Manuals

The memory feature will continue to work from the door control even
when deactivated at the remote entry module.
Replacing the battery
The transmitter is powered by one coin type three-volt lithium battery
CR2032 or equivalent. Typical operating range will allow you to be up to
10 meters (33 feet) away from your vehicle. A decrease in operating
range can be caused by:
²weather conditions
²nearby radio towers
²structures around the vehicle
²other vehicles parked next to the vehicle
To replace the battery:
1. Twist a thin coin between the two
halves of the transmitter near the
key ring. DO NOT TAKE THE
FRONT PART OF THE
TRANSMITTER APART.
2. Place the positive (+) side of new
battery in the same orientation.
Refer to the diagram inside the
transmitter unit.
3. Snap the two halves back
together.
Controls and features
108