One problem related to turn signal flasher unit has been reported for the 2004 Chevrolet Trailblazer. The most recently reported issues are listed below.
I was driving my Trailblazer to minneapolis and the turn signals were working fine, I stop and when I started driving again I went to use my left turn signal and the flashers went on instead. It continued to do this everytime I used it. I had to go and get the flasher modules replace at the cost of 200. 00. I see that there is a recall on this but my VIN # is not included in the recall.