IGNITION COIL TEST 3: Verifying Ignition Coil Is Getting 12 Volts
So far, you have verified that you do have a bonafide no spark situation coming directly from the ignition coil because:
One: Your Ford's no-start condition is due to a lack of spark (and nothing else).
Two: You have eliminated the ignition coil's high tension wire as bad (TEST 2).
The next test is to make sure the ignition coil is getting battery power either using a multimeter or a 12 V DC test light.
Alright, this is what you'll need to do:
- 1
With your multimeter still in Volts DC mode from the previous test and the key ON (but engine OFF).
- 2
Probe the wire labeled with the number 2 in the image viewer, with the red multimeter test lead.
- 3
Now Ground the black multimeter test lead on the battery's negative (-) Post.
- 4
Your multimeter should show you either: 1.) 12 Volts DC or 2.) 0 Volts.
Let's take a look at what your results mean:
CASE 1: The multimeter registered 12 Volts. This is the correct result and tells you that the next step is to check that the ignition coil is getting a switching signal from the ignition control module (ICM). Go to: IGNITION COIL TEST 4: Verifying The Switching Signal With A Test Light.
CASE 2: The multimeter DID NOT register 12 Volts. Double check your multimeter connections and repeat the test. If your multimeter results still do not indicate 12 Volts, then the ignition coil is not fried and not the cause of the no spark no-start problem, since without power, it won't work.
Although it's beyond the scope of this article to find the cause of these missing 12 Volts, resolving this issue will solve the no-spark no-start issue.
IGNITION COIL TEST 4: Verifying The Switching Signal With A Test Light
In the previous test you confirmed that the ignition coil is being supplied with power (12 Volts DC).
Now, you need to see if the ignition coil is getting an activation signal, called the switching signal, from the ignition control module (ICM).
This test is accomplished using a 12 volt test light and is done while cranking the engine on your 4.9L, 5.0L, or 5.8L Ford pick up (or car or SUV).
Alright, this is what you'll need to do:
- 1
Reconnect the high tension wire to the ignition coil and the distributor cap, if you haven't done so.
- 2
Probe the wire labeled with the number 1 in the image viewer with the test light's metal probe and.
Connect the test light's crocodile type connector to your Ford's battery positive post.
The ignition coil can be connected to its electrical connector or not. - 3
When ready, have your helper crank the engine while you observe and hold the test light in place.
- 4
Your 12 volt test light will either:
1.) Flash On and Off the whole time the engine is cranking.
2.) No flashing On or Off.
Let's take a look at what your results mean:
CASE 1: The test light flashed ON and OFF. This is means that the ignition control module is activating the ignition coil and since the ignition coil is not sparking, the ignition coil is bad. Replace the ignition coil.
Here's why: If the ignition coil is getting power (12 Volts) and is getting the switching signal, it HAS TO SPARK, since it isn't, this tells you that it's fried.
If you'd like to save a few bucks buying the ignition coil (and factory original Motorcraft ignition components), take a look at the following section: Where To Buy The Ignition Coil And Save.
CASE 2: The test light DID NOT flash ON and OFF. This test result exonerates the ignition coil, since without this switching signal, it won't spark.
The most likely cause of this missing switching signal is either a bad ignition control module (ICM) or a bad profile ignition pickup (PIP) sensor (which is Ford's fancy name for the crank sensor). I have written an article that will help you to test both of these at:
1.) If your Ford vehicle has the ignition control module mounted on the Distributor, go to: Ford Distributor Mounted Ignition Module And PIP Sensor Test (this article is found at easyautodiagnostics.com).
2.) If your Ford vehicle has the ignition control module mounted on the Fender, go to: Ford Fender Mounted Ignition Module And PIP Sensor Test (this article is found at easyautodiagnostics.com).
Why The HEI Spark Tester?
If you have read any of my ignition system test articles, you'll notice that I'm always writing the article around the HEI spark tester. Why? Well for several reasons and they are:
- 1
The HEI spark tester is accurate and this will save you money by helping make your diagnostic reach the right conclusion. Reaching the right conclusion always saves money.
How? Well, no other spark tester stress tests the ignition coil or the spark plug wire (high tension wire) like the HEI spark tester. The stress test that the HEI spark tester puts the ignition coil under, produces a spark or a no spark test result you can take to the bank.
- 2
The HEI spark tester does not cost an arm and a leg. It usually retails for around 10 to 14 US dollars (don't have an HEI spark tester? Need to buy one? You can buy it here: OTC 6589 Electronic Ignition Spark Tester).
- 3
You don't have to interpret the color of the spark on the HEI spark tester. On some spark testers, it's suggested that you have to interpret the color of the spark (which is total BS in the first place since the color of the spark has nothing to do with anything).
If the HEI spark tester sparks, the spark is present and strong enough. If it doesn't spark, then you have a bonafide no spark result you can trust. - 4
In the long years I've spent working as a diagnostic automotive technician, I have used a lot of different tools to test for spark and from personal experience I know it works and I can therefore recommend it to you.
Where To Buy The Ignition Coil And Save
The best place to buy the ignition coil (and any original Motorcraft ignition system components like: spark plug wires, distributor cap/rotor) and save a few dollars is online.
The following links will help you comparison shop for the ignition coil and the Motorcraft original spark plug wires your Ford uses:
Related Test Articles
I've written several more tutorials that may be of interest to you. These are specific Ford car (pick up, van) tutorials you can find here: Index Of Ford 4.9L, 5.0L, 5.7L Test Articles.
If you need a complete ignition system test article I recommend two I have written and located at easyautodiagnostics.com:
1.) If your Ford vehicle has the ignition control module mounted on the Distributor, go to: Ford Distributor Mounted Ignition Module And PIP Sensor Test (this article is found at easyautodiagnostics.com).
2.) If your Ford vehicle has the ignition control module mounted on the Fender, go to: Ford Fender Mounted Ignition Module And PIP Sensor Test (this article is found at easyautodiagnostics.com).
If this info saved the day, buy me a beer!
