How To Test The Ignition Coil -No Start Tests (Chrysler 3.9L, 5.2L, 5.9L)

The ignition coil on your Dodge Ram Pick Up, Ram Van, Dakota with the 3.2L, 5.2L, or 5.9L engine can be easily tested on the vehicle.

You don't need any expensive testing equipment like a scan tool. Not only that, the test can be accomplished in 4 easy tests, the results of which will let you know if the ignition coil is truly fried or not.

The tools you'll need are a test light, a multimeter (optional) and a helper (to help you crank the engine). All of the tests are explained in detail and in plain English (no technical automotive jargon).

If you're looking for the resistance test of the primary and secondary circuits, this article won't help you (in my opinion, the primary/secondary resistance test is a complete waste of time and life that does not work around 99% of the time to diagnose a bad ignition coil).

You can find this tutorial in Spanish here: Cómo Probar La Bobina De Encendido (Dodge 3.9L, 5.2L, 5.9L) (at: autotecnico-online.com).

Important Suggestions

TIP 1: Some of the tests, in this article, require that you perform them while cranking the engine. So it goes without saying: You've got to think safety all of time. Be careful, use common sense.

TIP 2: As a major safety precaution, keep your helper waiting outside the vehicle till you need him (or her) to crank the engine. Your helper should stay outside the vehicle and away from the ignition switch before you set up the test.

TIP 3: Quite a few things can cause your pick-up (van or SUV) to crank but not start. If you have already tested for spark and there IS spark from all 6 or 8 spark plugs (depending on whether you have a V6 or a V8), then the ignition coil IS NOT faulty.

If this is the case (in your case), the following article may be of help:

1. How To Test A No Start Condition (Dodge 3.9L, 5.2L, 5.9L).

Symptoms Of A Bad Ignition Coil

The surest symptom that the ignition coil (on your Dodge pick up, van, or SUV) has failed is that your vehicle will crank but not start due to a lack of spark.

Here are some more specific symptoms of this no spark condition:

1. You won't see spark firing from all of the spark plug wires.
2. The fuel injectors will still work and spray fuel into the cylinders.
3. The PCM will still activate the ignition coil.
   • This means that the ignition coil does receive the switching signal but fails to fire spark.
4. Crank sensor is good.

How Does The Ignition Coil Work?

The ignition coil is an amazingly simple device that is a key component of the ignition system on your Dodge pick up (or van or SUV).

The following is a very simple explanation of how it works that'll help you make sense of the tests I'll be showing you in the next pages.

It all starts when you turn the key and start cranking the engine, and in a nutshell, this is what happens:

1. As the engine starts to crank, the crankshaft position sensor (on the transmission's bell housing) starts to generate it's crank signal.
2. The PCM (Powertrain Control Module = fuel injection computer) gets the crank signal and then activates the ASD (Auto Shut Down) relay. Once this relay becomes activated, the ignition coil gets power (12 Volts).
   
   The ignition coil only gets power with the engine cranking or engine running.
3. At the same time the PCM activates the ASD relay, it starts to switch the ignition coil ON and OFF by interrupting the ignition coil's primary voltage.
4. Once the ignition coil gets this switching signal, it starts to spark away and as you're already aware, this spark gets delivered to the center of the distributor cap by a high tension wire.
5. By this time, the fuel injection computer is also injecting fuel into the engine, which the spark will ignite, thus the engine starts!

The cool thing is that you can check to see if the ignition coil has failed (and thus causing your Dodge pickup, van, or SUV from starting) by checking for two very specific things: spark and the switching signal and in this tutorial I'll show how.

OK, let's turn the page and start the first ignition coil test.