One problem related to automatic transmission torque converter has been reported for the 2006 Chevrolet Trailblazer. The most recently reported issues are listed below.
Pulling out on the road before oncomiing traffic and accelerated normal. The vehicle traveled about 10 to 20 yds when the engine rpm drasticly increased like the vehicle went into neutral, but the transmission was in d. It happened so quickly and before I could let my foot off the accelerator a very loud bang occurred in the driveline. I immediately let off the accelerator and began pulling out of the right lane of traffic on to the shoulder out of traffic. I attempted to increase acceleration with the vehicle in d and the rpm iincreased and no forward motion, shifted to 3 and tried again (nothing), shifted to 2 and then the transmision engaged and forward motion was established. Took vehicle to gm dealer and results were a broken sprag in the transmission. Gm rebuilt transmission to repair. Discussed with serv mgr the problem and he indicated that they see these sprags break quite often in this type of transmission. Doing further research after that I discovered that there are numerous occations of this vehicle with drive train problems in the transmission all throughout the veh mileage range from 4, 5000, 10000, and 34000 . Vehicle service up to date by my dealership and has been driven under normal conditions. The engine is a 6. 0 liter 395 hp, 400 ft\lb torque. I also noticed where gm first produced this vehicle with a lighter duty transmission 4l60-e, then upgraded to a 4l70-e and larger torque converter to withstand the power developed by the 6. 0 liter engine. Ther gm serv. Mgr indicated my vehicle had the 4l70-e transmission when I called him to discuss. There is still an issue with this particular circumstance with the heavier transmission not handllng the power developed. It is a safety hazard if quick acceleration was needed to cross an intersection or avoid oncoming traffic. Fortunately I wasnt crossing traffic and turning from the parking lot onto the road able to avoid oncoming traffic avoiding a serious accident. Trailblazer.