I replaced the battery in my RKE transmitter and now the lock button works sometimes and sometimes doesn't.

Take a look in the owners manual. In the older models there was a couple buttons you pressed and held to help the car relearn the transmitter if they had troubles like this.

ob reprogramming is more along the lines of using the scan tool of the dealership. If it is the remote that came with the car you may only need to resinc with the car which is done by being near the car and holding down both the lock and unlock buttons on the remote for about 7 secs.

If the dealership is need to reprogram, take all remotes to the car with you as they will need to be reprogrammed as well.

Some of the Gm'* cars are programmed via the drivers information center (DIC)

thanks