Visually inspect the spark plug cables for burns, cuts, or breaks in the insulation. Check the spark plug boots and the nipples on the distributor cap and the coil. Replace any damaged wiring. If no physical damage is obvious, the wires can be checked with an ohmmeter for excessive resistance. Remove the distributor cap and leave the wires connected to the cap. Connect one lead of the ohmmeter to the corresponding electrode inside the cap and the other lead to the spark plug terminal (remove it from the spark plug for the test). Replace any wire which shows over 50,000 ohms. Test the coil wire by connecting the ohmmeter between the center contact in the cap and either of the primary terminals at the coil. If the total resistance of the coil and cable is more than 25,000 ohms, remove the cable from the coil and check the resistance of the cable. If the resistance is higher than 15,000 ohms, replace the cable. If resistance is less, check the coil for a loose connection or for a bad coil. Check the top of the coil for cracks or carbon tracking.
REMOVAL & INSTALLATION
Replace spark plug cables one at a time when installing a new set, this way there can be no mix-ups. Refer to the firing order illustration if you do become confused. Start by replacing the longest cable first. Install the boot firmly over the spark plug. Route the wire exactly the same as the original. Insert the nipple firmly into the tower on the distributor cap. Repeat the process for each cable.