TEST 5: Testing The Ignition Coil For 12 Volts

How To Test A Misfire / No Spark-No Start Condition (4.3L, 5.0L, 5.7L 96-04)

Up this point, your diagnostic tests have confirmed that:

  1. All spark plugs are not sparking (TEST 1).
  2. The ignition coil's high tension wire is not sparking (TEST 3).
  3. The ignition coil's tower is not sparking (TEST 4).

In this test, you're going to verify that both the ignition coil and ignition control module (ICM) are being supplied with power (12 Volts), since both are fed this voltage thru' the same circuit.

If the ignition coil is getting power, then the next step is to make sure that it's getting an activation signal from the ignition control module.

These are the test steps:

  1. 1

    Place the multimeter in Volts DC mode.

    Don't have a digital multimeter? Need to buy one? Click here to see my recommendations: Buying A Digital Multimeter For Automotive Diagnostic Testing.

  2. 2

    Disconnect the ignition coil from its electrical connector.

  3. 3

    With the red multimeter test lead, probe the wire identified with the letter A in the photo. This should be the pink (PNK) wire of the ignition coil connector.

  4. 4

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

  5. 5

    Turn the key ON with the engine OFF.

  6. 6

    You should see 10 to 12 Volts on the multimeter.

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

CASE 1: Your multimeter displayed 10 to 12 Volts. This is the correct test result and it lets you know that the ignition coil and the ignition module are getting power.

The next step is to check to verify that the ignition coil is being fed with the Switching Signal that comes from the ignition control module (ICM). Go to: TEST 6: Verifying The Ignition Coil's Switching Signal.

CASE 2: Your multimeter DID NOT display 10 to 12 Volts. Without this voltage the ignition control module (ICM) nor the ignition coil will work.

You must find out why you're missing this voltage. Resolving this power issue should solve your no spark/no start problem.

TEST 6: Verifying The Ignition Coil's Switching Signal

How To Test A Misfire / No Spark-No Start Condition (4.3L, 5.0L, 5.7L 96-04)

For the ignition coil to start sparking, it needs a switching signal from the ignition control module. This Signal is verified, as being sent to the ignition coil, with an LED light (YOu can see an example of this tool here: The LED Light Test Tool And How To Make One).

You'll need to use an appropriate tool to pierce the wire so that you can attach the black lead of the LED to the wire being tested below.

IMPORTANT: This test is performed with the ignition coil and ignition control module connected to their respective connectors.

These are the test steps:

  1. 1

    Connect the black wire of the LED to the wire identified with the letter C of the ignition coil's connector (see photo above).

    NOTE: The ignition coil and the ICM must remain connected to their electrical connectors for this test to work.

  2. 2

    Connect red lead of LED to the battery positive (+) terminal. It is important that it be connected at the battery positive (+) terminal.

  3. 3

    Have an assistant crank the engine.

  4. 4

    The LED test tool should blink ON and OFF as the engine is being cranked.

    Don't worry about what the LED Light does before or after your helper starts cranking the engine. The only results you're interested in interpreting are the results obtained with the engine cranking.

Let's examine your test result:

CASE 1: The LED flashed ON and OFF. This is the correct test result and it confirms that the ignition coil is getting its activation signal.

You can conclude that the ignition coil is bad, and needs to be replaced, if you have:

  1. Confirmed that none of the spark plug wires are sparking (TEST 1).
  2. Confirmed that the ignition coil tower is not sparking (TEST 3 and TEST 4).
  3. Confirmed that the ignition coil and ICM are getting power (TEST 5).
  4. Confirmed that the ignition coil IS NOT getting its Switching Signal.

With this test result you can also correctly conclude that the ignition control module (ICM) and pick up coil are good. Replacing the ignition coil will solve your 'no spark no start' condition.

CASE 2: The LED DID NOT flash ON and OFF. Re-check all of your connections and retry the test again. If still no light pulses on the test LED, go to: TEST 7: Testing The Triggering Signal From PCM.

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