How To Test The Ignition Coil (1988, 1989, 1990 2.5L SOHC Dodge Dakota Pickup)

In this tutorial I'll explain how to test the ignition coil on the 1988, 1989, 1990 2.5L SOHC Dodge Dakota.

The tests are easy and best of all, with your test results you'll be able to find out if the ignition coil is bad or not.

When the ignition coil fails in your 2.5L Dodge Dakota, it's not going to start due to a lack of spark at all four cylinders.

You can find this tutorial in Spanish here: Cómo Probar La Bobina De Encendido (1988-1990 2.5L Dodge Dakota) (at: autotecnico-online.com).

You can find the typical ignition system circuit diagram here: Ignition System Wiring Diagram (1990-1993 2.5L Dodge Dakota).

The following tutorial will help you test the distributor pick-up coil: How To Test The Distributor Pick-Up Coil (1990-1995 2.5L SOHC Dodge Dakota).

Ignition Coil Circuit Descriptions

How To Test The Ignition Coil (1988, 1989, 1990 2.5L SOHC Dodge Dakota Pickup)

The ignition coil is a simple 2-wire component. One wire supplies 12 Volts and the other supplies an activation signal.

The activation signal comes directly from the fuel injection computer of your 2.5L SOHC Dodge Dakota.

Since we need to know what each wire does, here is a brief description of each one:

Pin Wire Color Description
1 Grey With Black Stripe (GRY/BLK) 12 Volts (from ASD Relay)
2 Black With Grey Stripe (BLK/GRY) Ignition Coil Control Signal

What Tools Do I Need To Test The Ignition Coil?

The most important tool you're gonna' need is a spark tester.

I recommend using an HEI spark tester. This spark tester is not expensive. Not only that but its spark test result is very accurate.

You can find out where to buy it here: The HEI Spark Tester.

The other tool you're gonna' need is a 12 Volt automotive test light.

TEST 1: Testing The Spark Plug Wires For Spark

Testing The Spark Plug Wires For Spark. How To Test The Ignition Coil (1988, 1989, 1990 2.5L SOHC Dodge Dakota Pickup)

To get started we're gonna' test the four spark plug wires for spark with a spark tester.

The photo above shows exactly how to connect your spark tester to the spark plug wire.

The purpose of testing all four spark plug wires is to see if spark is present for all four cylinders.

If all four spark plug wires spark then you can conclude that the ignition coil is good.

NOTE: You'll need to crank the engine to perform all of the spark tests in this tutorial. So be careful and take all necessary safety precautions.

These are the test steps:

  1. 1

    Disconnect the spark plug wire that connects to the spark plug of cylinder #1.

  2. 2

    Connect the HEI spark tester to the spark plug wire (see photo above).

  3. 3

    Ground the spark tester, using a battery jump start cable, to the battery negative (-) post.

  4. 4

    Have your helper crank the engine.

  5. 5

    The spark tester should spark as the engine cranks.

  6. 6

    Repeat the spark test on the remaining cylinders.

Let's examine your test result:

CASE 1: All of the spark plug wires sparked. This is the correct and expected test result and tells you that your 2.5L Dodge Dakota's ignition coil and its high tension wire are not defective.

With this test result you can also conclude that the pick-up coil inside the distributor is OK too.

If the engine in your 2.5L Dodge Dakota is not starting then you can conclude that it's not caused by a bad ignition coil or a bad pick-up coil.

CASE 2: All four spark plug wires DID NOt spark. Without spark the engine is not gonna' start.

The next step is to test the ignition coil's high tension wire for spark. For this test, go to: TEST 2: Testing The Ignition Coil's High Tension Wire For Spark.

CASE 3: Some of the spark plug wires did not spark. This test result tells you several things. First of all you can conclude that the spark plug wires that did not spark are defective and that all of the spark plug wires need to be replaced.

You can also conclude that the ignition coil is good since you did get spark from some of the spark plug wires.