After many tries by the dealer, they finally located the problem. It was a faulty steering wheel angle sensor. Do a search on this forum for the sensor and you find many threads, some by me
, on this topic. The 07/08 Chevy Trial Blazers are notorius for this sensor going bad...they have their own forum and many threads on this topic. It is funny that the dealer does not have this in their database as something to look at.