- Inspect the coil for external leaks and arcing; replace the ignition coil if any are found. Every time an ignition coil assembly is replaced because of a burned tower, carbon tracking, arcing at the tower, or damage to the nipple or boot on the coil end of the coil wire (secondary cable), replace the cable (coil wire). Any arcing at the tower will carbonize the nipple so that placing it on a new coil assembly will invariably cause another coil failure. If coil wire shows any signs of damage, the coil wire (secondary cable) should be replaced since carbon tracing on an old cable can cause arcing and ruin a new coil assembly.
To perform this test on the coil, you have to fashion or purchase a particular jumper wire tool. You'll need two simple wires several feet long with alligator clips on the ends. A third wire must incorporate a capacitor of 0.33 MicroFarad capacitance. The materials and components needed to make up such jumpers should be available at a reasonable price in a local electronics store. Refer to the accompanying diagram for the make-up of the jumper wire tool.
- With a Digital Volt-Ohmmeter (DVOM) measure the battery voltage at the battery terminals and note it. Battery voltage must be at least 12.4 volts to adequately test the coil.
- Disconnect the coil secondary wire (the high tension cable) from the distributor cap.
- With the ignition key ON and by using the special jumper wire (refer to the accompanying diagram), hold the coil secondary cable approximately 1 / 4 in. (6mm) from a good engine ground with insulated pliers (or similar insulated tool) and momentarily touch the negative (-) terminal of the coil to ground. A strong, blue-white spark should be obtained. If no spark was obtained, proceed with the test, otherwise the ignition is functioning within normal parameters.
- Turn the ignition key OFF and on non-lean burn ignition systems, detach the 5-way electrical connector from the ignition control module. If equipped with the lean burn ignition system, disconnect the 10-way dual connector from the Spark Control Computer (SCC).
Do not remove the grease from the electrical connector or the connector cavitythis grease is used to prevent moisture from corroding the connector terminals.
- With the ignition key ON and using the special jumper wire (refer to the accompanying diagram), once again hold the coil secondary cable approximately 1 / 4 inch from a good engine ground with insulated pliers (or similar insulated tool) and momentarily touch the negative (-) terminal of the coil. A strong blue-white spark should be obtained.
- If no spark was obtained, proceed with the test, otherwise the controllers output circuit is shorted. Replace the control module (non-lean burn system) or the SCC (lean burn systems) with a new one and try to start the vehicle.
- Measure the voltage at the ignition coil positive (+) terminal. The voltage should be within one volt of the aforemeasured battery voltage. If the voltage is not as specified, there is a wiring fault between the battery and the coil.
- If the voltage was within one volt, measure the battery voltage at the ignition coil negative (-) terminal. This should also be within one volt of the battery voltage. If this voltage is within specifications and no spark was produced in Step 4 and Step 7, the ignition coil is faulty and should be replaced with a new one. If the correct voltage is not exhibited at the coil negative terminal, the coil is also faulty and must be replaced with a new one.
- If the vehicle still does not start, the problem lies elsewhere.
REMOVAL & INSTALLATION
- Disconnect the negative battery cable.
- Using a small wrench or socket and ratchet wrench, remove the positive and negative coil terminal attaching nuts. Label, then pull the positive and negative terminal wires from the ignition coil terminal studs.
- Grasp the ignition coil secondary cable (high tension wire) on the boot and pull it from the ignition coil center tower.
- Remove the ignition coil mounting bracket retaining bolt and remove the coil and bracket from the engine compartment.
- Slide the ignition coil out of the mounting bracket.
- Slide the new ignition coil into the mounting bracket.
- Position the ignition coil and bracket in place.
- Install the ignition coil bracket mounting bolt until secure.
- Push the secondary ignition coil onto the ignition coil center tower and make sure that the terminal engages the wire fully.
- Slide the positive and negative wires eyelets over their respective ignition coil terminal studs, then install the terminal attaching nuts until snug. Make certain that the positive wires are connected to the positive terminal and the negative wires to the negative terminal.
- Connect the negative battery cable.