Accidentally used an old key to start a newly programed system
Our 2004 Pontiac Montana was recently
recalibrated and given new keys. I found my old
key and accidentally tried to start the car. Now no
keys work. What can I do to start my van?
Sometimes waiting 15-20mins you can try to start the car again with the proper key. Put the new key in and turn to the first position and wait for the antitheft to go out, then start the vehicle. If that doesn't work, remove the negative battery cable from the battery for 20mins, and reconnect, then try the procedure above again. It should start. Then throw out the old one.