- 1). Unplug the spark plug wires from the coils located on the passenger side of the engine compartment bolted to the end of the cylinder. Twist as you pull the rubber boots on the plug wire to unsnap them from the coils.
- 2). Cut four 1-inch-long pieces of rubber vacuum line. Slip each piece over the coil towers where the spark plug wires were attached. Slip the spark plug wires onto the end of the vacuum line so the spark from the coil can reach the plug wire when the engine is running.
- 3). Start the engine. Attach the battery clip on the end of the test light's cable to the negative battery terminal. Hold the probe end of the 12-volt test light near each piece of vacuum line and watch for a spark. Move the probe end close enough to the rubber vacuum line for the spark to jump to the test light probe. This grounds the spark so that it can't fire the plug.
- 4). Ground the spark for each coil tower, one at a time, and listen to the engine. If it stumbles, the cylinder is firing. If you can touch the test light probe to the rubber vacuum line without a spark jumping, the coil is faulty and requires replacement.
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