No. 1 Additional Key Registration Procedure (Using 2 Valid Keys) Conditions

WARNING: This page is about a different car, the 2004 Mazda RX-8. However, it is still accessible from the selected car via links, so may be relevant.

Customer has two or more valid keys.
NOTE:
- A maximum of eight keys can be registered for any one vehicle. If key registration is not successful and DTC 15 appears even though the procedure was performed properly, use the PID/data monitor function of the WDS or equivalent and verify the number of keys that have been registered.
- If eight keys have already been registered, and it is necessary to register other keys, the previously registered key ID numbers must first be cleared. Perform key ID number clearing according to "No. 3 Key Replacement Procedure (Clearing Previously Registered Key ID Numbers, Key Registration)" .
Procedure

Fig 1: Identifying Valid & Registration Key
Courtesy of MAZDA MOTORS CORP.

Have an additional key (key 3) ready for registration.
Using key 1, turn the ignition switch to the ON position.
Verify that the security light illuminates for approx. 3s and then goes out.
Using key 1, turn the ignition switch to the LOCK position within approx. 4 s after the security light goes out.
Remove key 1
Repeat Steps 2- 5 using key 2.
Repeat Steps 2- 5 using key 3.
If additional keys need to be registered, repeat Steps 1- 7 in the same manner as key 3.