How To Test The Ignition Coil (1989-1991 5.2L, 5.9L V8 Dodge Ram Pickup)

TEST 3: Testing The Ignition Coil's High Tension Wire For Spark

If you've made it this far, that means none of the 8 spark plug wires fired spark during TEST 1.

In this part, we're gonna check if the ignition coil's high tension wire is delivering spark when you crank the engine.

If you see the spark tester sparking away, then the ignition coil's working —the issue is with the distributor cap or rotor. They're the reason your Dodge Ram pickup's engine won't start (and why there's no spark at the spark plug wires).

If the spark tester doesn't spark, then you'll move on to TEST 4 and check for spark directly in the ignition coil's tower.

Here's how to run this test:

1. 1

   Unplug the high tension wire from the center of the distributor cap.
   
   NOTE: Leave the other end of that wire connected to the ignition coil.

2. 2

   Attach the spark tester to the end of that wire —the side that was connected to the distributor cap (see the photo above).
   
   NOTE: You're testing the coil's output thru its high tension wire, so the other end (of the wire) must stay plugged into the ignition coil.

3. 3

   Ground the spark tester by hooking it up to the battery's negative (-) terminal using a jumper cable.

4. 4

   Have your assistant crank the engine while you hold the spark tester and watch closely.

5. 5

   The spark tester should fire spark the entire time the engine is cranking.

Let's break down what your results mean:

CASE 1: The spark tester sparks. That's the result you're looking for.

This confirms that the problem is in the distributor cap or rotor —but only if both of these are also true:

• You already verified that none of the spark plug wires are sparking (from TEST 1).
• You just confirmed that the ignition coil wire is sending spark (in this test).

To fix your V8 Dodge Ram pickup's no-start issue, go ahead and replace all the spark plug wires with a new set.

Although not necessary, if your spark plugs, cap, and rotor are just as old as those wires, it's smart to replace them too —get a clean, fresh start.

CASE 2: No spark from the tester. That means the distributor isn't getting any spark from the ignition coil.

Your next step is to check the ignition coil directly at the tower. Head over to: TEST 4: Testing The Ignition Coil For Spark.

TEST 4: Testing The Ignition Coil For Spark

If you've gotten this far, then TEST 1 and TEST 3 confirmed the following:

• TEST 1: None of the eight spark plug wires are sparking.
• TEST 3: The ignition coil's high tension wire isn't sparking either.

Now it's time to check for spark straight from the ignition coil's tower —just like you see in the photo above.

If you do get spark from the coil's tower, then the ignition coil is working —the issue is the high tension wire itself. It's not sending the spark to the distributor cap (this is actually a pretty common failure). That's what's causing the no-spark no-start problem.

If there's still no spark at the ignition coil's tower, then we'll move on to the next step: TEST 5.

Here's how to run this test:

1. 1

   Unplug the high tension wire from the ignition coil.

2. 2

   Attach your spark tester directly to the ignition coil's tower (refer to the photo above).

3. 3

   Ground the spark tester by connecting it to the battery's negative (-) terminal using a jumper cable.

4. 4

   Have your assistant crank the engine while you watch the spark tester.

5. 5

   You should see the tester spark the whole time the engine is cranking.

Now let's look at what your result means:

CASE 1: You got a steady spark. That's the result you want.

This means the ignition coil itself is working fine. If you've already confirmed the following:

• None of the spark plug wires sparked in TEST 1.
• The ignition coil's high tension wire didn't spark in TEST 3.
• You just saw spark coming directly from the coil in this test.

Then the problem is clear —the high tension wire from the coil is bad. Replace it and all of the other spark plug wires with a new set to get your engine started.

CASE 2: No spark from the tester. Alright, your next step is to check whether the coil is getting power.

To check for power, head over to: TEST 5: Making Sure The Ignition Coil Is Getting 12 Volts.

TEST 5: Making Sure The Ignition Coil Is Getting 12 Volts

Now we're gonna make sure the ignition coil is actually getting power —specifically 10 to 12 Volts. Without that voltage (which comes from the Auto Shutdown Relay, or ASD relay), the coil won't fire any spark at all.

The wire that delivers this voltage is the gray (GRY) or a dark green with black stripe (DK BRN/BLK) wire, and it connects to the ignition coil terminal marked with a (+) symbol.

In the photo above, I've marked this wire with the number 1.

We'll use a multimeter to check for voltage at that wire while the engine is cranking —that part's key. You won't get an accurate reading unless the engine's being cranked.

CAUTION: This test requires you to crank the engine to check for voltage, so take all necessary safety precautions and stay alert while working around a cranking engine!

Alright, let's get started:

1. 1

   Set your multimeter to read DC Volts.

2. 2

   Touch the red test lead to the ignition coil terminal marked with the (+) symbol.
   
   NOTE: You don't need to unplug the wire from the terminal to do this.

3. 3

   Connect the black test lead to the battery's negative (-) terminal.

4. 4

   Have your helper crank the engine while you watch the multimeter display.

5. 5

   You should see a reading of 10 to 12 Volts.

Let's break down what your reading means:

CASE 1: You see 10 to 12 Volts on the (+) terminal. That's the result you want —it means the ignition coil is getting the power it needs.

Since the issue you're troubleshooting is an 'engine no-spark no-start,' the next thing to test is whether the ignition coil is receiving its activation signal. Head to: TEST 6: Testing The Ignition Coil's Activation Signal.

CASE 2: No voltage on the (+) terminal. That tells you the ignition coil isn't getting power —so it can't create spark.

This usually comes down to one of the following:

• A break in the wire (that connects to the (+) terminal) between the ignition coil connector and the ASD (Auto Shutdown) relay.