How To Test The Ignition Coils Pack (1997-2000 4.2L V6 Ford F150, F250 Light Duty)

TEST 8: Checking The IC Activation Signals

If you've reached this test section, your tests have confirmed:

• All six spark plug wires do not spark (TEST 1).
• The RED/LT GRN wire is delivering 12 Volts to the ignition coil pack (TEST 4).

In this section, we'll check for the presence of the activation signals for ignition coil 1, 2, and 3 with a 12 Volt automotive test light (non-powered test light).

Here's the ignition coil's connector pinout:

• Terminal 2: DK BLU/LT GRN wire - activation signal cylinders 1 and 5.
• Terminal 3: PNK/WHT wire - activation signal cylinders 2 and 6.
• Terminal 4: RED/LT BLU - activation signal cylinders 3 and 4.

IMPORTANT: Be careful not to damage the female terminal or the connector with your 12V test light's probing tip. If the terminal or the connector get damaged, you'll need to replace the connector.

CAUTION: This test has to be performed with the engine cranking. Be careful and take all necessary safety precautions.

Alright, let's start:

1. 1

   Disconnect the ignition coil (IC) from its 4-wire electrical connector.

2. 2

   Connect the 12V test light's alligator clip to the battery positive (+) post.

3. 3

   With the test light's probing tip, gently probe terminal number 2.

4. 4

   Have your helper crank the engine.

5. 5

   The 12V test light should flash ON and OFF the whole time the engine is cranking.

6. 6

   Repeat steps 2 thru 5 on female terminals 3 and 4.

Let's find out what your test result means:

CASE 1: The 12V test light flashed ON and OFF the whole time the engine was cranking on each terminal. With this test result you can conclude that the PCM is providing the activation signals for all three ignition coils (within the coil pack).

You can conclude that the ignition coil pack is bad if you have:

• Confirmed that all six spark plug wires are not sparking (TEST 1).
• Confirmed that the ignition coil is getting power (TEST 4).
• Confirmed that the ignition coil pack is receiving all three IC activation signals (this test section).

CASE 2: The 12V test light did not flash on and off at any of the terminals while the engine was cranking. This test result usually means that the crankshaft position (CKP) sensor.

Your next step is to test the CKP sensor:

• How To Test The CKP Sensor With A Multimeter (1997-2003 4.2L V6 Ford F150, F250).

Other Things That Can Cause A Misfire

If you've tested the ignition coil and all its six towers are sparking, yet the engine is still misfiring, this section will give you a few more testing suggestions that might help you find the source of the problem.

It's important to note, that quite a few components, when they fail, will cause the engine to misfire. This is what I suggest:

1. Check For Carbon Tracks:
   • Carbon tracks tend to develop on the spark plug's porcelain insulator and the inside of the spark plug boot. The main cause of a carbon track is oil leaking from the valve covers.
   • Inspect the inside of the spark plug wire boots and the ceramic insulator of the spark plug for carbon tracks.
   • The the orange arrows in the photo above point to what carbon tracks look like.
   • Replace the components as affected with carbon tracks.
2. Check For Damaged Spark Plug Wires:
   • The most common issue is a broken or damaged spark plug boot. The boot covers the spark plug wire's metal terminal. If it's damaged, the metal terminal becomes exposed, causing the spark to jump to the exhaust manifold instead of the spark plug.
   • Another frequent problem I've encountered is a spark plug wire with a missing or detached metal terminal. This usually happened during a previous ignition system repair or diagnostic and the issue went unnoticed.
   • Replace any spark plug wire that has a damaged boot or is missing its metal terminal.
3. Look for Burned or Cut Spark Plug Wires:
   • If the spark plug wires aren't routed correctly, they can touch the exhaust manifold or a sharp edge on the engine. This contact causes the wire to get burned or cut. When this happens, the spark can jump from the damaged part of the wire to the Ground, causing a misfire because the spark never reaches the spark plug.
   • Replace any spark plug wire that shows signs of burning or cutting.
4. Check For Low Cylinder Compression:
   • One of the most overlooked diagnostic tests to find the root cause of misfire is the compression test.
   • You'll need an engine compression tester of course.
   • The engine between cylinders should not vary more 15%.
   • How To Do An Engine Compression Test (1997-2008 4.2L V6 Ford F150, F250).
5. Check For A Bad Or Clogged Fuel Injector:
   • 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 and comparing them to each other.
   • Any resistance that's not within the average of the others indicates the fuel injector is fried.
   • You can buy a specific fuel injector tester online that activates by a predetermined pulse width and measuring the fuel pressure drop on a fuel pressure gauge.
   • How To Test The Fuel Injectors (1997-2000 4.2L V6 Ford F150, F250).

More 4.2L Ford F150 Tutorials

There are quite a few 4.2L V6 F-150 pickup 'how to' tutorials and wiring diagrams you can find in this index:

• 4.2L Ford F150 And F250 Index of Articles.

F-Series Vans: You can find all of the available tutorials and wiring diagrams for the 4.2L V6 E-Series vans in this index:

• 4.2L Ford E150 And E250 Index of Articles (at: troubleshootmyvehicle.com).