Removal

• 1). Disconnect the TrailBlazer's negative battery cable using a wrench on the cable's clamp nut.
  
  
• 2). Loosen the hose clamps securing the main duct to the air cleaner system using a screwdriver and detach the duct and its resonator from the throttle body.
  
  
• 3). Unplug the electrical connector for the individual ignition coil, remove the coil's single bolt with a wrench and pull the coil out of the valve cover. Don't touch the other coils until you have finished changing this spark plug.
  
  
• 4). Blow out all dirt and contaminants from the spark plug's hole using compressed air.
  
  
• 5). Insert a socket wrench with a spark plug socket and extension into the hole and unscrew and remove the spark plug. Turn the socket counterclockwise, just like you do most other objects that require a wrench.
  
  

Installation

• 1). Apply a dielectric anti-seize compound to the new spark plugs on its threads only. Do not get any compound on the porcelain surface or the electrodes.
  
  
• 2). Thread the spark plug into its hole in the engine. Attaching a 5/16-inch diameter hose (about 3 to 6 inches long) to the plug will help, as it will give you more room and help prevent you from cross-threading the plug (see Tips).
  
  
• 3). Tighten the plug the rest of the way with the spark plug socket.
  
  
• 4). Reconnect the ignition coil using its bolt and electrical connector.
  
  
• 5). Repeat on the other spark plugs. Reconnect the air duct and resonator with its clamps once you have changed all the plugs.
  
  
• 6). Connect the battery cable.