Ignition Systems Overview Chapter 36 Ignition Systems Overview

Performing a Spark Test 36-1 Remove the high-tension lead or coil from the end of the spark plug.

Performing a Spark Test 36-1 Connect a spark tester to the boot of the coil or high-tension lead, and attach the clamp to a good ground.

Performing a Spark Test 36-1 Crank the engine and watch for a spark across the tester electrodes. A properly functioning ignition system will produce a blue spark. If there is no spark present, test the spark plug wire or coil, distributor cap, and rotor on that plug. If there is still no spark present, continue on to the next skill drill.

Inspecting the Primary and Secondary Circuits 36-2 Remove the secondary wire from the center terminal of the distributor cap, install a spark tester, and crank the engine to see if there is any spark coming out of the ignition coil.

Inspecting the Primary and Secondary Circuits 36-2 Use a test light or connect the red lead of a multimeter to the positive terminal at the coil and the black lead to a good ground with the key switched on. A typical reading is 10 to 12 volts. If using a test light, the light should illuminate brightly.

Inspecting the Primary and Secondary Circuits 36-2 Place the red meter lead (or the test light probe) on the negative side of the coil and the black lead on a good ground. Crank the engine. The test light or meter should oscillate, indicating the coil is being triggered. If there is power present and the coil is being switched, proceed with checking the coil. If there is no power to the positive side and/or no switching at the negative side, the ignition coil or primary wiring may be defective.

Testing the Ignition Coil 36-3 Inspect and test ignition primary and secondary windings of the ignition coil(s). All the coil terminals should be clean, secure, and free of corrosion.

Testing the Ignition Coil 36-3 To test the resistance of the primary windings, place the ohmmeter leads on each of the two primary winding terminals. If the reading is not within specifications, the coil is faulty and must be replaced.

Testing the Ignition Coil 36-3 To test the secondary windings, place one ohmmeter lead on the secondary tower terminal and the other to one of the primary terminals, or the coil secondary ground, if equipped. If the reading is not within specifications, the coil is faulty and must be replaced.

Testing the Ignition Coil 36-3 If the coil readings are OK, perform a spark test as in Skill Drill 36-1 to verify that the coil can produce a spark which will jump at least ½” (13 mm).

Testing a Spark Plug Wire 36-4 Disconnect the spark plug wire at both ends by grasping the boots on the ends and twisting while pulling the wire off. Inspect each wire for cracks, brittleness, or burnt spots.

Testing a Spark Plug Wire 36-4 Place one lead of the ohmmeter on each end of the spark plug wire. Flex the wire while reading the ohmmeter. A good wire will have a maximum of 3000 to 7000 ohms of resistance per foot of wire.

Testing a Spark Plug Wire 36-4 Replace the spark plug wires, start the engine, and lightly mist water on the spark plug wires or run a grounded test lead along each wire. If the readings are not within specifications or if the wires arc, replace the spark plug wires, making sure to route them in their factory positions to prevent damage.

Inspecting a Distributor Cap and Rotor 36-5 Remove the distributor cap from the top of the distributor by unscrewing it or removing the clips.

Inspecting a Distributor Cap and Rotor 36-5 Check for cracks, carbon tracks, and burned terminals, and also check the center terminal for wear.

Inspecting a Distributor Cap and Rotor 36-5 Check the rotor for burned contacts and cracks in the plastic housing. If the rotor is held in place by a retaining screw, make sure it is tight.

Replacing the Spark Plugs 36-6 Check the electrode gap of each spark plug by finding the correct‑sized gauge on the gapping tool and attempt to place it between the center and the side electrode.

Replacing the Spark Plugs 36-6 To gain access to a spark plug, first remove the spark plug wire by gripping its boot by hand or with a high-tension wire puller and gently pulling it off of the spark plug.

Replacing the Spark Plugs 36-6 Clean out the spark plug pocket with compressed air.

Replacing the Spark Plugs 36-6 Remove the spark plug, using the correct-sized spark plug socket.

Replacing the Spark Plugs 36-6 If the new plugs are equipped with a gasket, ensure they are installed properly. Install the spark plugs by hand to avoid cross‑threading. Use a torque wrench to properly tighten the spark plug.

Replacing the Spark Plugs 36-6 Once the spark plug is installed, reinstall the spark plug wire by pushing it on to the terminal of the spark plug until it snaps into place.

Replacing the Spark Plug Wires 36-7 Remove one end of the wire (or boot) from the distributor cap, coil pack, or COP coil. Remove the other end from the spark plug with a high-tension wire puller by twisting the boot on the spark plug while gently pulling it off.

Replacing the Spark Plug Wires 36-7 If dielectric grease is specified for the spark plug boots, use a cotton swab to spread a small amount around the inside of the boot.

Replacing the Spark Plug Wires 36-7 Install the new spark plug wire by pushing one end onto the spark plug and the other onto the distributor cap, coil pack, or COP coil. The spark plug wires should be routed in their factory positions to prevent damage.