I know this is an old thread but I'll just post relevant info if it happens to others:
These chirps just stopped on our 2008 Rogue SL AWD.
I found the buzzer in front of the radiator and took it out.
Tested it, it's broken. Measured the signals at the plug, voltage pulses arrive when locking/unlocking using the door handle buttons.
Will replace with a generic piezo buzzer and put it in a more protected location.
The Nissan factory manual calls the part the 'INTELLIGENT KEY WARNING BUZZER' - it's in the DLK section.
The lookup code on parts.nissanusa.com is 25640G
There it's called 'BUZZER ASSY-KEYLESS & CARD ENTRY'
The current part number is
25641-C990E (this superseded the old part # 25641C990A)
MSRP is $70. Current price online $50+.
Location of the buzzer is shown in the DLK section of the factory manual on page DLK-305 (for the 2008 Rogue).
The manual says to remove the bumper and front grille for access, I was able to reach and remove it through the large slots under the license plate.
