Where are the spark plugs on a 2002 Chevrolet Trailblazer?

The spark plugs on a 2002 Chevrolet Trailblazer are located on top of the engine, under the plastic engine cover. You'll need to remove the engine cover to access them. They're arranged in a V-shape following the cylinder heads of the engine. Because there are different engine options available for that year (inline-6 or V8), the exact location within that top-engine arrangement will vary slightly. A repair manual specific to your Trailblazer's engine (the displacement will be listed on your vehicle's paperwork or the engine itself) will give you the most precise location and instructions.