TEST 4: Testing The Power (12 Volts) Circuit
All three ignition coils inside the coil pack rely on the same power source, which is the red (RED) wire connected to terminal 4 of the coil pack's 4-wire connector.
In this test section, we're going to check that terminal 4 has battery voltage present with the key in the RUN position, but with the engine OFF.
If battery voltage is present at terminal 4, we'll move on to TEST 8, which is making sure the coil pack is getting all of its ignition coil activation signals.
NOTE: Be very careful when probing the female terminals of the coil pack 4-wire connector. There's a good chance your multimeter's probe may be a bit too thick for the terminal itself. If you damage the terminal, you'll end up having to replace the entire connector —and that's something you definitely want to avoid.
All right, let's begin.
- 1
Disconnect the ignition coil from its connector.
- 2
Put the multimeter in Volts DC mode.
- 3
Connect the black multimeter test lead to the battery negative (-) terminal.
- 4
Gently probe the front of female terminal 4 with the red multimeter test lead (using an appropriate tool).
Female terminal 4 should connect to the RED wire of the coil pack's 4-wire connector. - 5
Have your helper turn the key to the ON position (no need to crank the engine).
- 6
You should see 10-12 Volts on your multimeter.
Let's find out what your test result means:
CASE 1: The coil pack has power. This is exactly the test result we needed to see.
Now that we've confirmed the coil pack is getting power, our next step is to see if it's getting all three activation signals from your Ford Taurus or Mercury Sable's PCM. Head over to: TEST 8: Checking The IC Activation Signals.
CASE 2: The coil pack has no power. Double-check that you're testing the correct terminal and that it connects to the RED wire of the coil pack's 4-wire connector.
If after retesting the terminal you still don't see battery voltage present, then we can rule out the coil pack itself as the cause of the engine no-start problem you're troubleshooting.
Your next step is to figure out why this circuit is missing battery voltage and restore it. Once the RED wire is delivering 10 to 12 Volts, the coil pack will function and start generating spark for all six cylinders.
TEST 5: Activation Signal For Cylinders 1 And 5
Up to this point, your coil pack diagnostic tests have confirmed the following:
- The spark plug wires that connect to paired cylinders 1 and 5 don't spark when cranking the engine (TEST 1).
- You've checked the coil pack towers for cylinders 1 and 5 and they aren't sparking either (TEST 3).
To continue our diagnostic, we now need to make sure that the individual coil inside the pack —the one responsible for firing cylinders 1 and 5— is getting its activation signal from your Ford Taurus or Mercury Sable's PCM.
This is a super easy test to do and it only requires a standard automotive 12-Volt test light. This test light should be a non-powered test light that uses an incandescent bulb.
The activation signal for the 1/5 ignition coil comes through the yellow with black stripe (YEL/BLK) wire, which connects to terminal 1 of the coil pack's 4-wire connector.
IMPORTANT: Be careful when probing the female terminal of the connector with your test light's metal probe. If the terminal or the connector gets damaged, you'll need to replace the whole connector.
CAUTION: To check the activation signal, you're going to need to crank the engine. So be careful, stay alert, and take all necessary safety precautions while working around a cranking engine.
NOTE: If you don't own a 12 Volt test light with an incandescent light bulb, this is the one that I use and recommend: Lisle 28400 Heavy Duty 12 Volt Test Light (Amazon affiliate link).
Alright, let's start:
- 1
Disconnect the ignition coil from its 4-wire electrical connector.
- 2
Connect the 12V test light's alligator clip to the battery positive (+) post.
- 3
With the test light's probing tip, gently probe terminal number 1.
Female terminal 1 should connect to the YEL/BLK wire. - 4
Have your helper crank the engine.
- 5
The 12V test light should flash ON and OFF the whole time the engine is cranking.
Let's find out what your test result means:
CASE 1: The 12-Volt test light flashed ON and OFF while cranking. This test result confirms that the powertrain control module (PCM) is doing its job and sending an activation signal to the ignition coil (within the pack) responsible for generating spark for cylinders 1 and 5.
We can safely conclude that the coil pack is bad and needs to be replaced if everything below has been verified:
- In TEST 1, you found that the spark plug wires for cylinders 1 and 5 aren't sparking.
- In TEST 3, the coil pack towers for cylinders 1 and 5 also do not spark.
- In this test, you confirmed that the PCM is sending the activation signal to the coil pack.
When you're ready to buy the new coil pack, these are the ones I recommend. They're from known automotive brands that I've been using my entire automotive repair career:
- Standard Motor Products FD-498T Ignition Coil Pack (Amazon affiliate link).
- Motorcraft - Coil Pack Assy (DG532) (Amazon affiliate link).
CASE 2: The 12-Volt test light did NOT flash ON and OFF. This test result tells you that the ignition coil within the pack responsible for generating spark for cylinders 1 and 5 isn't getting its activation signal from the PCM.
Go ahead and double-check your test connections and make sure you're testing the correct terminal, and that this terminal connects to the YEL/BLK wire.
If you still don't see the test light flashing ON and OFF, then we can rule out the coil pack itself as the cause of the no-spark result you've gotten so far. Your next step is to find out why this activation signal is missing and restore it to the circuit. Once the coil pack starts receiving the 1/5 activation signal, you'll see spark for those cylinders again.
TEST 6: Activation Signal For Cylinders 2 And 6
Your last two tests confirmed the following:
- The spark plug wires for cylinders 2 and 6 aren't sparking (TEST 1).
- The coil pack towers feeding those two wires also don't spark (TEST 2).
This usually means that the coil pack itself is bad and needs to be replaced. But to be absolutely sure, we need to confirm that the PCM is actually sending the 2/6 activation signal to the ignition coil (within the pack) that fires spark to those two cylinders.
This is a very easy test to do, and it's done with a simple 12-Volt non-powered automotive test light —the type that uses an incandescent bulb. If you don't have one and need to buy one, this is the one I use and recommend: Lisle 28400 Heavy Duty 12 Volt Test Light (Amazon affiliate link).
We're going to check the 2/6 activation signal at female terminal 2 of the coil pack's 4-wire connector. Terminal 2 is the one that connects to the yellow with white stripe (YEL/WHT) wire of the coil pack connector.
The 2/6 activation signal is carried through female terminal 2 of the coil pack's 4-wire connector. This terminal is tied to the yellow with white stripe (YEL/WHT) wire.
IMPORTANT: Be careful when probing the female terminal of the connector with your test light's metal probe. If the terminal or the connector gets damaged, you'll need to replace the whole connector.
CAUTION: To check the activation signal, you're going to need to crank the engine. So be careful, stay alert, and take all necessary safety precautions while working around a cranking engine.
Alright, let's start:
- 1
Disconnect the ignition coil from its 4-wire electrical connector.
- 2
Connect the 12V test light's alligator clip to the battery positive (+) post.
- 3
With the test light's probing tip, gently probe terminal number 2.
Female terminal 2 should connect to the YEL/WHT wire. - 4
Have your helper crank the engine.
- 5
The 12V test light should flash ON and OFF the whole time the engine is cranking.
Let's find out what your test result means:
CASE 1: The 12-Volt test light flashed ON and OFF while cranking. This lets us know that your Ford Taurus or Mercury Sable's PCM is sending the 2/6 activation signal to the coil pack.
We can conclude that the coil pack is toast and needs to be replaced only if all of the following are true:
- In TEST 1, you confirmed that the spark plug wires for cylinders 2 and 6 don't spark.
- In TEST 3, you confirmed coil pack towers for cylinders 2 and 6 also aren't sparking.
- In this test section, you've confirmed that the PCM is sending the 2/6 activation signal to the coil pack.
When you're ready to buy the new coil pack, here are the ones I recommend —they're from known automotive brands I never hesitate to recommend:
- Standard Motor Products FD-498T Ignition Coil Pack (Amazon affiliate link).
- Motorcraft - Coil Pack Assy (DG532) (Amazon affiliate link).
CASE 2: The 12-Volt test light did NOT flash ON and OFF while cranking. Without this signal, the ignition coil (within the pack) responsible for producing spark for cylinders 2 and 6 won't create any spark for them.
Double-check that you're testing the correct terminal and that it actually connects to the YEL/WHT wire of the coil pack connector. If the test light still doesn't flash ON and OFF, then we can conclude that the PCM isn't sending the 2/6 activation signal.
The most likely cause of this missing 2/6 activation signal is an open-circuit problem in the YEL/WHT wire between the coil pack connector and the PCM. Your next step is to figure out why this activation signal is missing from the circuit and restore it. Once this signal is available to the coil pack, it'll generate spark for cylinders 2 and 6.
TEST 7: Activation Signal For Cylinders 3 And 4
Up to this point, the spark test results of TEST 1 and TEST 3 have confirmed the following:
- The spark plug wires that connect to cylinders 3 and 4 aren't sparking.
- The coil pack towers that connect to those spark plug wires also aren't sparking.
For our final coil pack diagnostic test, we're going to check that the yellow with red stripe (YEL/RED) wire of the coil pack's 4-wire connector —the one that connects to terminal 3— is delivering the 3/4 activation signal.
This 3/4 activation signal is generated by your Ford Taurus or Mercury Sable's PCM, and you and I can easily check for the presence of this signal (while cranking the engine) with a basic 12-Volt automotive test light —the non-powered style with an incandescent bulb.
If you don't have one, this is the one I use and recommend, and you can buy it here: Lisle 28400 Heavy Duty 12 Volt Test Light (Amazon affiliate link).
IMPORTANT: Be careful when probing the female terminal of the connector with your test light's metal probe. If the terminal or the connector gets damaged, you'll need to replace the whole connector.
CAUTION: To check the activation signal, you're going to need to crank the engine. So be careful, stay alert, and take all necessary safety precautions while working around a cranking engine.
Alright, let's start:
- 1
Disconnect the ignition coil from its 4-wire electrical connector.
- 2
Connect the 12V test light's alligator clip to the battery positive (+) post.
- 3
With the test light's probing tip, gently probe terminal number 3.
Female terminal 3 should connect to the YEL/RED wire. - 4
Have your helper crank the engine.
- 5
The 12V test light should flash ON and OFF the whole time the engine is cranking.
Let's find out what your test result means:
CASE 1: The 12V test light flashed ON and OFF the whole time you cranked the engine. This test result confirms that the ignition coil responsible for generating spark for cylinders 3 and 4 is getting an activation signal from the PCM.
We can now say that the coil pack is bad and has to be replaced, but only if the following is true:
- The spark plug wires for cylinders 3 and 4 did not spark in TEST 1.
- The coil pack towers for cylinders 3 and 4 did not spark in TEST 3.
- In this final test, you've confirmed the presence of the 3/4 activation signal.
When you're ready to buy the new coil pack, I want to make the following recommendations. Both of these coil packs are from known automotive brands that I never hesitate to recommend.
- Standard Motor Products FD-498T Ignition Coil Pack (Amazon affiliate link).
- Motorcraft - Coil Pack Assy (DG532) (Amazon affiliate link).
CASE 2: The 12V test light DID NOT flash ON and OFF while cranking the engine. This test result tells you that the coil pack isn't receiving an activation signal to fire spark to cylinders 3 and 4.
Double-check that you're probing the correct terminal and that it connects to the YEL/RED wire of the connector, and repeat the test. If the test light still doesn't flash on and off, then we can rule out the coil pack itself as bad, since without this activation signal the coil pack won't fire spark to cylinders 3 and 4.
The most likely cause of this missing activation signal is an open-circuit issue in the YEL/RED wire, between the coil pack connector and the PCM. Your next step is to find out why this signal is missing and solve the issue —once the coil pack receives it, it'll generate and send spark to cylinders 3 and 4.