How To Test The Ignition Coil (1995-2000 2.0L Dodge Stratus, Plymouth Breeze)

TEST 8: Making Sure The Ignition Coil Pack Is Getting Its Activation Signals

So far, you've verified that:

• There's no spark in any of the spark plug wires (TEST 1).
• The coil pack is receiving between 10 and 12 Volts DC (TEST 5).

Next, we'll focus on ensuring that the ignition coil pack is receiving its activation pulses. Specifically, we're gonna be looking at:

• The activation signal for cylinders #1 and #4.
• The activation signal for cylinders #2 and #3.

The activation signal is simply an ON/OFF toggling of the Ground that the fuel injection computer supplies to each coil within the pack. This ON/OFF toggling of the Ground (in the signal wire) is what triggers the ignition coil to fire off spark.

The wires that deliver these activation signals are:

• The dark blue with dark green stripe (DK BLU/DK GRN) wire (cylinders #1 and #4).
  • NOTE: In some vehicles, this wire is a dark blue with tan stripe (DK BLU/TAN) wire.
• The black with grey stripe (BLK/GRY) wire (cylinders #2 and #3).

We'll use a simple LED light to carry out the checks for these activation signals. If you don't have one, you can find out more about it and where to buy one here: The LED Light Test Tool And How To Make One (at: easyautodiagnostics.com).

These are the test steps:

1. 1

   Disconnect the ignition coil pack from its connector.

2. 2

   Connect the red lead of the LED light to the battery positive (+) terminal with a long jumper cable.
   
   NOTE: You can also insert the end of the red LED wire into middle female terminal of the connector (which will have 10 to 12 Volts with the engine cranking). Just be careful that the wire doesn't damage the female terminal, or you'll have to get a new connector.

3. 3

   With an appropriate tool, connect the black lead of the LED light to the BLK/GRY wire of the ignition coil pack connector.
   
   The BLK/GRY wire is the one that feeds the cylinder #2 and #3 activation signal to the ignition coil (within the coil pack). The BLK/GRY wire connects to the female terminal labeled with the number 3 in the illustration above.
   
   NOTE: You can also insert the end of the black LED wire into the female terminal of the wire. Just be careful that the wire doesn't damage the female terminal, or you'll have to get a new connector.

4. 4

   Have your helper crank the engine while you observe the LED light.

5. 5

   If the activation signal is present, the LED light will flash ON and OFF the whole time the engine was cranking.

6. 6

   Remove the LED light's black lead from the ignition coil pack's connector (or wire).

7. 7

   Repeat step 2 on the DK BLU/DK GRN wire of the connector.
   
   The DK BLU/DK GRN wire connects to the female terminal with the number 1 in the illustration above.
   
   NOTE: In some vehicles, this wire is a dark blue with tan stripe (DK BLU/TAN) wire.

8. 8

   Have your helper crank the engine while you observe the LED light.

9. 9

   If the activation signal is present, the LED light will flash ON and OFF the whole time the engine was cranking.

Let's take a look at what your test results mean:

CASE 1: The LED light flashed ON and OFF the whole time the engine was cranking (in both terminals). This is the correct test result and it confirms that the fuel injection computer (PCM) is providing the activation signals and the circuits are OK.

This result confirms that the ignition coil pack is bad and needs to be replaced only if you have:

• Confirmed that all four spark plug wires do not spark (TEST 1).
• Confirmed that all four ignition coil pack towers do not spark.
• Confirmed that both of the ignition coil pack's activation signals are present (this test section).

CASE 2: The LED light DID NOT flash ON and OFF the whole time the engine was cranking (in both terminals). Without these activation signals, the ignition coil pack will not fire off spark to any of the cylinders.

The most likely cause of these missing signal is a bad crankshaft position (CKP) sensor. Your next step is to test the CKP sensor:

• How To Test The CKP Sensor (1995-2000 2.0L Dodge Stratus, Plymouth Breeze).

Other Possible Misfire Causes

So, your ignition system diagnostic shows that the ignition system isn't causing the cylinder misfire you're dealing with. Well, I've got a couple of suggestions that might help.

1. Inspect the inside of the spark plug wire boots and remove the spark plugs to visually check their ceramic insulators for carbon tracks
   • The photo above points (the orange arrows) to what carbon tracks look like.
   • Replace any spark plug or spark plug wire with carbon tracks.
   • The following case study on carbon tracks may come in handy: Carbon Tracks Are A Common Cause Of Ignition Misfires (at: easyautodiagnostics.com).
2. Inspect the inside of all of the spark plug tubes. It's possible that the valve cover spark plug tube seals are leaking engine oil into the spark plug tubes.
   • If engine oil is filling up the tubes, you'll need to replace the valve cover gasket along with the spark plug tube seals, the spark plugs, and the spark plug wires.
3. Engine compression test.
   • This is one of the easiest, yet most overlooked test to find the cause of a misfire condition.
   • You'll need an engine compression tester of course.
   • The engine compression value recorded on the compression gauge (between cylinders) should not vary more 15%.
   • You can find a step-by-step compression test tutorial here: How To Test The Engine Compression (1995-2000 2.0L Dodge Stratus and Plymouth Breeze).
4. Fuel injector test.
   • There are several methods to test them which are beyond the scope of this article but the fastest way to test them is by checking the resistance (Ohms) value of each one with a multimeter and comparing the Ohms values to each other.
   • Any resistance that's not within the average of the others indicates the fuel injector is fried. If the Ohms readings are nearly identical to each other, you can rule them out as the cause of the misfire.
   • Or you can buy a specific fuel injector tester (on line) that activates the fuel injector by a predetermined pulse width in conjunction with a fuel pressure gauge that will show you the fuel pressure drop this tester will cause.