Where is the engine control module located on a 2004 trailblazer?

The engine control module (ECM) on a 2004 Chevrolet Trailblazer is typically located under the hood, near the front driver's side of the vehicle. It is mounted on the firewall, just behind the engine, and is secured with bolts. To access it, you'll usually need to remove some covers or components, such as the air intake duct. Always consult a repair manual for specific instructions related to your vehicle.