GM Service Manual Online
For 1990-2009 cars only

Spark Plug Wires Not Operating Properly L36 and L67

Removal Procedure

Caution: Wash your hands after handling coated spark plugs and before smoking. The coating is a non-hazardous material and incidental contact will not cause any adverse effects. However, exposure to polymer vapors - the result of contamination of cigarette products and subsequent burning of the polymer - may result in flu-like symptoms and should be avoided.

Notice: Note the spark plug wire harness routing during harness removal. Improper routing during installation can cause the following conditions:

   • Radio noise
   • Ignition noise
   • Spark plug crossfiring
   • Ground lead shorts
   • Cutting and chaffing of the wires

  1. Turn OFF the ignition.
  2. Remove the engine cover.
  3. Notice: Twist the spark plug boot one-half turn in order to release the boot. Pull on the spark plug boot only. Do not pull on the spark plug wire or the wire could be damaged.

  4. Remove the spark plug wire harness from the ignition coils.
  5. Remove the harness from the spark plugs.

  6. Object Number: 42121  Size: SH
  7. Remove the complete harness from the vehicle.

Installation Procedure


    Object Number: 42121  Size: SH
  1. Install the harness to the spark plugs.
  2. Install the harness on the ignition coils.
  3. Install the harness on clips.
  4. Install the engine cover.