Mazda CX-9 Grand Touring 2009 Manual page 2031

Condition
Have two or more valid keys.
NOTE:
Procedure
Fig. 86: Additional Key Programming Procedure
Courtesy of MAZDA MOTORS CORP.
1. Prepare key 3 for programming.
2. Start the engine using key 1.
3. Verify that the security light illuminates for approx. 3 s , and then goes out.
4. Turn the ignition switch to the LOCK position.
5. Using key 1, turn the ignition switch to the ON position.
6. Verify that the security light illuminates for approx. 3 s , and then goes out.
7. Using key 1, turn the ignition switch to the LOCK position within approx. 4 s after the security light
goes out.
8. Remove key 1.
9. Repeat Steps 5-8 using key 2 instead of key 1.
2008 Mazda CX-9 Grand Touring
2008 BODY & ACCESSORIES Security and Locks - Mazda CX-9
A maximum of eight keys can be programmed for one vehicle. If key
programming is not successful and DTC 15 appears even though the
procedure was performed properly, use the PID/data monitor function
of the M-MDS and verify the number of keys that have been
programmed.
If eight keys have already been programmed, and it is necessary to
program other keys, the previously programmed key ID numbers
must first be cleared. To clear the key, refer to " CLEARING CARD
KEY [ADVANCED KEYLESS SYSTEM]".