My 2000 grand prix needs the key reprogramed. I lost the original key and now the new one wont program on its own.

Make sure you have the right type of ignition keys, there should be a stamp on the keys "PK3" which is the right ignition keys you need to have for your passlock system.

Auto Relearn:
Time required, approximately 10 minutes.

Insure that the battery is fully charged.
Turn the ignition switch from the OFF position to the CRANK position attempting to start the vehicle. The vehicle will start and then stall.
Leave the ignition switch in the ON position while observing the security indicator.
When the security indicator turns off, which can take up to 10 minutes, turn the ignition switch off. Wait 10 seconds.
The BCM and the PCM will learn the new code on the next start attempt.

You may have to get somebody with a scan tool to reset the computer codes to make this work.

Thank oyu for using fixya and good luck