This problem has really got me stumped. I have a 2005 G35 Coupe, sport with 37k miles on it.

About a week ago I noticed a change on how my car locks.

When I used to press the lock button on my keyfob the car would beep. This seems normal to me.

All of a sudden it stopped doing that. Now when I lock the door there isn't a sound at all, no beep no nothing. I thought it might be the horn that died but the panic alarm still works.

What is happening as well about every 30 min the cars back lights flash for about 1 second and it seems to try to lock the car again (even if its already locked)

This has been going on for a week, I am worried that this might be a sign of something that is wrong.

Can anyone help me out, and explain what is going on?

 

THe answer is in your owner's manual. If you hold both lock and unlock on the remote it will toggle between beep on lock to the other mode no beep on lock. The autolocking you are noticing is the car relocking the doors when you unlocked the car and didn't open the door.