One problem related to horn assembly has been reported for the 2004 Chevrolet Trailblazer. The most recently reported issues are listed below.
Car died on exit ramp of 290 and thorndale. Pushed car to side of road where we noticed smoke coming from under hood. Upon opening hood saw fire coming from filter under air cleaner compartment. Flagged down police officer who helped put out fire with fire extinguisher. Had car towed to advantage Chevrolet who said they had never seen anything like this and perhaps a cigerette got sucked in and started the fire. Contacted gm who sent out a rep and could not explain fire so he concluded gm was not responsible under warranty because the car must have sucked in some foreign object and it was not a mechanical failure. Car was repaired under my insurance, who is fighting the claim. Parts replaced were air cleaner compartment, ducts, clamps, sensors, snorkel, element etc. Was told old parts were in back of car, but when we looked parts were missing. Dealer still looking for parts. No one has yet to address why car died in the first place.