Mazda 2009 MX-5 Miata Owner's Manual page 68

Knowing Your Mazda
Advanced Keyless Entry and Start System
3. Insert the flathead screwdriver into the
gap between the cover and the
transmitter, and then rotate the
screwdriver to detach the cover.
4. Remove the battery cap, then remove
the battery.
3-6
5. Insert a new battery with the positive
pole facing up, and then cover the
battery with the battery cap.
6. Close the cover.
7. Reinsert the auxiliary key.