One problem related to emission control has been reported for the 2005 Chevrolet Trailblazer. The most recently reported issues are listed below.
In March 2007 the check engine light came on and stayed on . I took vehicle to dealer to have it checked out. It turned out to be the secondary air pump either clogged, not running or something electrical with it. Ever since then all the exterior and interior lights became bright then dimmed for a few minutes when I start the vehicle. After leaving for work and stopping the vehicle to turn, and then again a few miles down the road, the headlamps started to flicker. Sometimes it flickered a few more times before I got to work , only 25 minutes from home. I have noticed the battery gauge fluctuated while this is happened. I was told that this was normal. Also, I am not sure this was related, but ever since the check engine"light problem the air conditioning system did not work properly. It didn't work on 5, but it did blow some on the other levels, and that varied too. I have had the air conditioning recharged, to no avail, it acted like there was a leak somewhere. Hopefully ,gm or someone else will find the solution before there was an electrical fire or even a case of road rage due to other drivers thinking I wa s flashing the bright lights at them.