Troubleshooting The Ignition Module (Ford 4.6L Coil Pack Ignition)

This article will help you to troubleshoot the ignition control module (ICM) on the Ford 4.6L V8 equipped cars that use the ‘coil pack’ ignition system.

Whether you're troubleshooting a 'no-start no-spark' condition or a misfire condition, this article will help you.

The ignition control module test I've written up here is an on-car test you can do yourself and that can be done (and has to be done) without a scan tool. For those of you who own an oscilloscope, I've also included the pertinent waveforms.

This article only covers the coil pack equipped Ford vehicles (with a 4.6L) that have an ignition control module (ICM) activating the coil packs. The vehicle's without an externally mounted ignition module are not covered.

You can find this tutorial in Spanish here: Cómo Probar El Módulo De Encendido (Ford 4.6L Con Sistema DIS) (at: autotecnico-online.com).

Symptoms Of A Bad Ignition Control Module

In my experience, the ignition control module fails in one of two ways.

• The failure will cause a misfire condition.
  • When this happens you'll have two dead ‘Paired’ cylinders. By this I mean that they get spark at the exact same time from two of the four coil pack towers.
  • When this happens, you'll see one of the following:
    • P0301 Cylinder #1 Misfire & P0306 Cylinder #6 Misfire.
    • P0302 Cylinder #2 Misfire & P0308 Cylinder #8 Misfire.
    • P0303 Cylinder #3 Misfire & P0305 Cylinder #5 Misfire.
    • P0304 Cylinder #4 Misfire & P0307 Cylinder #7 Misfire.
  • And so, if you have a misfire, this means that you'll get a rough idle.
  • If you have two missing cylinders, then your gas mileage sucks!
  • Lack of power as you accelerate the vehicle down the road.
  • On the rare occasion, you may also see:
    • P0320 Profile Ignition Pickup (PIP) Input Circuit Malfunction.
    • P0350 Ignition Coil Primary Circuit Malfunction.
    • P0351 Ignition Coil Primary A Circuit Malfunction (Coil Driver for Cylinders 1 and 6 Malfunction).
    • P0352 Ignition Coil Primary B Circuit Malfunction (Coil Driver for Cylinders 3 and 5 Malfunction).
    • P0353 Ignition Coil Primary C Circuit Malfunction (Coil Driver for Cylinders 7 and 4 Malfunction).
    • P0354 Ignition Coil Primary C Circuit Malfunction (Coil Driver for Cylinders 2 and 8 Malfunction).
• Or the bad ignition module will cause a no-start condition.

What Tools Do I Need?

You don't need anything expensive. This is what you'll need:

1. A multimeter (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. A Wire-Piercing Probe to pierce the wire.
   • If you need to see what this tool looks like, click here: Wire-Piercing Probe.
3. A 12 Volt automotive test light.
   • This test light can not be a logic probe or a powered test light like the Power Probe, just a simple 12 Volt test light.

Ignition Module Circuit Descriptions

There are 12 wires sticking out of the ignition module's connector, in this section we'll explore what each one does.

• Circuit labeled 1:
  • Profile Ignition Pickup (PIP) Signal output.
• Circuit labeled 2:
  • Ignition Diagnostic Monitor Signal (IDM) output.
• Circuit labeled 3:
  • Spark Output (SPOUT) Signal input.
• Circuit labeled 4:
  • CKP Sensor Input (+).
• Circuit labeled 5:
  • CKP Sensor Input (-).
• Circuit labeled 6:
  • Power Source (12 Volts in START/RUN).
• Circuit labeled 7:
  • Ignition Ground
• Circuit labeled 8:
  • Switching Signal output for Cylinders #1 and #6
• Circuit labeled 9:
  • Switching Signal output for Cylinders #3 and #5
• Circuit labeled 10:
  • Ground
• Circuit labeled 11:
  • Switching Signal output for Cylinders #4 and #7
• Circuit labeled 12:
  • Switching Signal output for Cylinders #2 and #8

You might already be thinking/asking yourself: Do I have to test them all to find out if the ignition control module is bad? The answer is NO, you don't.

OK, to get this show on the road, lets turn the page and read up on the ‘Ignition Module Basics’.

Ignition Module Basics

The ignition control module is the one that activates the two coil packs to start sparking away and also sends the PCM the signal to start injecting fuel.

In this section, I'll go into some brief working theory of how the ignition module works. Don't worry, it won't be anything too technical.

Here in a nutshell is what happens when you open the key and start cranking the engine in your car:

1. The ignition module gets power (in the form of 12 Volts) thru' wire labeled with the number 6.
   • Ground is provided thru' two wires and they are the wires labeled with the number 7 and number 10.
2. The crankshaft position (CKP) sensor starts to produce and send its crank signal to the ignition module.
   • The CKP sensor signal is received on the wires labeled with the number 3 and number 4.
   • The crank signal is an A/C voltage signal that you can measure with a multimeter in A/C Volts or with an oscilloscope.
3. As soon as the ignition control module gets the crank signal, it starts to activate the ignition coil packs to fire spark.
   • Specifically, the module sends 2 unique switching signals to each of the coil packs.
   • The passenger side coil pack gets one switching signal that activates spark for ‘Paired’ Cylinders #1 and #6. The other switching signal activates ‘Paired’ Cylinders #3 and #5.
   • The driver side coil pack gets one switching signal that activates spark for ‘Paired’ Cylinders #4 and #7. The other switching signal activates ‘Paired’ Cylinders #2 and #8.
   • If you're wondering what the heck is a switching signal: It's the turning On and then Off of the Ground of the Primary Voltage (the fancy mancy name for 12 Volts) flowing thru' the ignition coil. It's this switching ON and OFF of the Ground that makes the ignition coil fire off spark.
4. The ignition control module also sends a Profile Ignition Pick (PIP) signal that the PCM uses to start activating the fuel injectors.
   • The PIP signal is sent to the PCM thru' the wire labeled with the number 1.
   • The PIP signal is only sent after the ignition module gets the CKP sensor signal.
5. Once the engine has started, the PCM Sends the SPOUT (Spark Out) signal to the ignition module
   • The SPOUT signal is sent from the PCM to the ignition module thru' the wire labeled with the number 3.
   • The SPOUT signal is the one that provides the ignition timing advance and dwell info the module needs to control ignition timing.
6. Last, but not least, the ignition control module provides the PCM with an IDM signal.
   • IDM stands for Ignition Diagnostic Monitor.
   • This signal is sent thru' the wire labeled with the number 2.
   • The IDM signal is the one that provides the PCM with ignition system failure info. This signal is also used to activate the tachometer (if equipped).
7. After all of the signals are created and exchanged, the engine in your vehicle starts.
   • The two most critical signals are the crankshaft position sensor signals and the PIP signal. Without these, your car will crank but not start.

It looks and sounds like a lot of stuff is happening to get the car started, but as you'll soon see, the testing (of the ignition module) is pretty simple and easy.

Where To Start The ICM Diagnostic

I know you're itching to get testing right away, but it's important you read this section before jumping into TEST 1 (since TEST 1 may not apply to you).

This article tests for 3 different type of ignition control module (ICM) failures and each has a different starting point in the article. Specifically:

1. A no-start condition where:
   • You have a no-spark condition from all of the spark plug wires.
   • No fuel injector pulses from any of the fuel injectors.
   • This is usually caused by a bad crankshaft position sensor or a bad module.
   • Your starting point is TEST 1: Checking For Power.
2. A no-start condition where:
   • You have spark from all of the spark plug wires.
   • Fuel injector pulses are present for the fuel injectors.
   • This is usually caused by a bad module not providing the PIP signal.
   • Your starting point is TEST 3: Checking The PIP Signal.
3. A misfire condition where:
   • The car starts and runs but runs with 2 dead cylinders.
   • These 2 cylinders are ‘Paired Cylinders’ (meaning they get spark at the exact same time from one of the ignition coils within the coil pack).
     • Cylinders #1 and 6 are ‘Paired Cylinders’.
     • Cylinders #3 and 5 are ‘Paired Cylinders’.
     • Cylinders #4 and 7 are ‘Paired Cylinders’.
     • Cylinders #2 and 8 are ‘Paired Cylinders’.
   • This is usually caused by a bad module not creating a switching signal for the affected cylinders.
   • Your starting point is TEST 5: Checking The Ignition Coil Driver Signals.