One problem related to brake hoses, lines/piping, and fittings has been reported for the 2003 Chevrolet Trailblazer. The most recently reported issues are listed below.
Driving approx 70mph on the highway, suddenly heard a "whap whap whap" noise coming from the back of the vehicle. I slowed down, and the sound diminished. Arriving home, I found that the center brake light assembly had come loose at both ends. The two center connections luckily held, or else the piece would have come off the car and possibly caused an accident. I have read that other Trailblazers have had the same issue.