Spark Plug Cable: Description

Spark Plug cables are sometimes referred to as secondary ignition wires. The wires transfer electrical current from the electronic ignition coils to the individual spark plug at each cylinder. The nonmetallic spark plug cables have built in resistance. The cables provide suppression of radio frequency emissions from the ignition system.

Check the spark plug cable connections for good contact at the coil or coil pack and at the spark plugs. Terminals should be fully seated with audible click. The nipples and spark plug covers should be in good condition. Nipples should fit tightly on the coil or coil pack and spark plug cover should fit tight around spark plug insulators. Loose cable connections can cause ignition malfunctions, corroding, and increasing resistance. To maintain proper sealing at the terminal connections, the connections should not be broken unless testing indicates high resistance, an open circuit or other damage. 

Clean high tension cables with a cloth moistened with a non-flammable solvent and wipe dry. Check for brittle or cracked insulation. Plastic clips in various locations protect the cables from damage. When the cables are replaced the clips must be used to prevent damage to the cables.