One problem related to automatic transmission control module has been reported for the 2004 Chevrolet Trailblazer. The most recently reported issues are listed below.
The vehicle has stalled out 3 times in the past month. Check engine light came on and then reduced engine power light. We could only go 10 mph. Thankfully we were in a residential area and not on the freeway. Dealership said it was a faulty accelerator position module and the pcm needed to be reprogrammed. Lucky us we are over in miles and this is not covered by the warranty.