found this also found a thing that says the acheiva uses passkey
PASSKEY & PASSKEY 2
This system consists of: the Powertrain Control Module (ECM or PCM), Body Control Module (BCM) or Passkey theft deterrent module, and the ignition lock and key. In most cases, the theft deterrent duties are handled by a Passkey module. In those vehicles, if you are replacing a key, all you must do is match the resistance of the existing key that is in use. If you replace the theft deterrent module, then the module will learn the existing key resistance with the first start up sequence. At that point, the resistance is permanently memorized by the module, and can no longer be changed. No relearn is necessary. In this situation, the vehicle will start and run with no problem. If the vehicle won’t start, check your scan tool for a VTD (Vehicle Theft Deterrent) Fail-Enable Mode trouble code, or if the security light on the dash is illuminated. If you have this code, then the vehicle probably is equipped with a BCM, and you must perform a relearn.
The next section applies only to those vehicles that use a BCM.
For those vehicles that use a BCM, the BCM can learn the resistance value of the existing key by using the relearn process. In order for the vehicle to start, the BCM (as well as the Passkey module in other vehicles) must identify the resistor pellet in the key, then the BCM sends a password to the PCM. If this password matches the password stored in the PCM, the system enables fuel delivery. So you can see that if either the BCM or PCM are replaced, a relearn procedure is necessary. This same relearn procedure can be used if an ignition key with a different resistance value is used to replace the existing key. Before beginning the relearn, make sure there is a fully charged battery in the vehicle, and both the BCM and PCM are properly powered up and in communication with each other. Now you’re ready to initiate the relearn procedure.
1. First, insert the ignition key and turn the ignition switch to the “On” position (Do not start the engine). Leave the switch on for 11 minutes. The security light may flash or be on steady during this 11 minute period. Make sure the light is no longer on or flashing before proceeding to #2 .
2. Turn the ignition switch off for 30 seconds.
3. Turn the ignition switch to the “On” position (as in step #1) for 11 minutes again.
4. Turn the ignition switch off for another 30 seconds.
5. Turn the ignition switch to the “On” position for 11 minutes a third time.
6. Turn the ignition switch off for 30 seconds one final time.
7. Turn the ignition switch to the “On” position one final time and wait 30 seconds.
8. Attempt to start the engine. If the engine starts and runs normally, the relearn is complete. If the engine does not start, check for trouble codes and address them before attempting the relearn procedure again.
1998 Bonneville SSE
2007 Monte Carlo LT-KYB, Clarion, Polk audio, Kicker
1999 Yukon SLE-KYB, Air lift, Reese dual-cam, Tekonsha
1987 Firebird-355/th400-nothing stock