One problem related to transmission stuck in gear has been reported for the 2004 Chevrolet Trailblazer. The most recently reported issues are listed below.
This was actually the second or third incident where the key got stuck in the ignition, blazer was in park the lights remained on so did the radio anything that is typically on during aux, but this was the beginning of a long problem that lead to me trading off. . The key gets stuck you can not remove it caused the battery to go bad, it would begin to happen often the service engine soon light would come on, the transmission would not shift above 3rd gear, also shortly after the purchase in sept of 2011 the speedometer stopped working. The blazer died 3 times gauges on dash would periodicly stop working. My service 4 wheel would come on randomly the key issue was the biggest problem but it was only a matter of time before other things went wrong. When the key would get stuck in the igintion as stated the transmission would not shift properly in the beginning the transmission would act out once you took it out of park it was noticeable but as the problem became worse it started happening driving down the highway I noticed once that I have successfully made it through 1-2-3 but never got out of 3. I should state that when the key was stuck I would have to manually shift through the first and second then put it into drive otherwise the car had no power because it would be stuck in the higher gear. Tried to contact the dealership as there was a recall on the dash for the 2003 model and they told us it wasnt a safety problem I do not understand how random loss of power and random car dying is not a safety issue, I have been watching the list of gm recalls and I have not seen much about the Trailblazers, and it bothers me that I am sure there are other issues like the ones that I had. On another note transmission related my neighbors just had to get rid of their Trailblazer 2006 for transmission problems.