When it is suspected that one or more spark plugs may not be firing and the spark plug wires do not seem to be at fault, this test offers a quick check to see if the ignition module and coil packs are producing spark voltage.
- Turn the ignition to the OFF position, then tag and disconnect all 4 spark plug wires from the ignition module towers.
Make sure that you are not touching the vehicle, then have an assistant crank the engine for a few seconds. Sparks should appear alternately between each pair of ignition coil towers while the engine is cranking.
NOTEDo not crank the engine for more than a few seconds at a time or starter damage may occur. Crank the engine for a few seconds, then release the ignition key and pause for an equal amount of time before cranking the vehicle again.
- If sparks appear between the 2 towers, the DIS module, Crankshaft Position Sensor (CPS) and the ignition coil packs are known to be good.
- If a single coil pack is suspect from an initial spark test, or no sparks appeared between its 2 towers, switch the coil pack to the opposite position on the ignition module (the coil packs are interchangeable) and check to see if the problem follows it. If the problem follows, the coil pack must be replaced. If the formerly good coil pack does not produce spark when switched with the suspect coil on the module, and the suspect coil works in the new position, then the ignition module is bad and must be replaced. Also, using an ohmmeter, check the resistance across the suspect coil's towers; it should be 7,000-10,000 ohms.
If no spark can be found across any tower, proceed with the NO SPARK TEST.