It sounds like a security problem, I would try the below process and see if it will start. If it does start the lock cylinder will need to be replaced at some point.
1. Perform a security system relearn. 2. Let the vehicle sit for more than 10 minutes with the key off. 3. Attempt to start the engine, leave the key in the run position monitoring the security system indicator. 4. After 10 minutes, the security indicator will change state. 5. Turn the key off and wait 10 seconds. 6. Attempt to start the engine. If the engine stalls, wait another 10 minutes with the key on. 7. After the second 10 minute timer has expired, turn the key off for 10 seconds. 8. Attempt to start the engine. If the engine stalls, wait another 10 minutes with the key on. 9. After the 3rd 10 minute timer has expired, shut the key off for 10 seconds. 10. The security system will relearn on the 4th starting attempt and the engine should start and run.
I believe I have made a mistake, I was thinking your system was a passkey III system but now I believe it is a passkey II system with a chip in the key, right? If this is right the problem is most likely the lock cylinder in the column, these are known to have broken wires that send the data to the computer to tell it that the right key is being used. To check this you would need a ohm meter and be able to find the wires under the dash that go up to the lock cylinder, there is usually two very small wire inside a plastic shield usually gray or orange. If you unplug the wires and connect the ohm meter they should ohm to the same amount as the chip in the key(be sure the key is in the ignition) if the wires do not the lock cylinder will need to be replaced.