'Is there any theft protection inside the programming that the computer needs to get any feedback from some unit which is matched to the computer?''
NO!
"or is my garage crap?"
YES!
"or what can I do?
Any hotline of Buick can help to solve this question?"
NO!
Do you have Auto Climate Control? (Do you have digital display)
If so, you have a common failure on the Buick, the fan speed control module. It is located in the fan box on the firewall under the relay & fuse center. You can order one from the following links.
http://www.rockauto.com/catalog/catalog.php
RockAuto Parts Catalog
http://www.partsamerica.com/