The short answer is, yes you can! Your LTZ can actually recognize more than two fobs. The issue is that a new fob that you purchase online is going to come with the mechanical key portion (the key that flips out) blank, and I think only the dealer can cut this to match your car. You *do* need this to work in the door lock in order to program the fob to the car.
The instructions are in the owner's manual, but essentially go like this:
- Place the existing remote in the special holder in the center console (the place you would stick the remote in the event that the remote's battery was too weak to operate normally)
- Remove the cap that covers the manual key cylinder on the driver door and insert the key (this is where it's necessary to have your new key cut to match the car). Rotate it to the unlock position and back five times within 10 seconds. You should see the message "READY FOR REMOTE
#x " on the DIC (where "x" is 2, 3, 4 or 5).
- Swap your new key fob into the special holder in the center console (replacing your working one) and press your START/STOP button. The DIC will indicate that it has accepted the new remote, and say that it's ready for the next transmitter.
- Press and hold the START/STOP button for 12 seconds or so - this will exit programming mode.
Inasmuch as I think you've got to hit the dealer to cut the key anyways, you're probably just as far ahead to let them finish the job - though you can certainly buy the new fob online for way less than the dealer is likely to charge, so there is that. I'd considered popping the key portion of the working fob out and installing it in the new fob - that way you can place the working fob in the center console and have a working key on your replacement remote to complete the programming process. In the end, though, you'd wind up with a second remote that works but which is totally useless to you in the event of a dead battery or other fault with the keyless entry system. Someone else on the forum likely has more insight.
