Thanks for posting back operator error.
Indeed, both keys must be done during the same session, and within a specific time period...AND...do NOT insert the 2nd or any other key into the ignition. If you insert another key in the ignition to initate programming...any key previously programmed will no longer work unless you proceed to reprogram it during the same session...starting on STEP #3 where it says to start pressing the buttons.
In fact, if you ever lose a remote key...you should reprogram your remaining remote, then if you get another remote, reprogram them again. This will cancel remote lock/unlock abilities of the lost remote key. Obviously, you can still walk up to the vehicle and insert the key manually...but all remote operation will no longer work if the other remotes have been reprogrammed. The GM III assigns new rolling code tables to the remote keys when the initializing sequence is initiated (STEP
#2).
Simple rules...but they
ALL must be followed specifically as written.
