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:
- 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).
- A Wire-Piercing Probe to pierce the wire.
- If you need to see what this tool looks like, click here: Wire-Piercing Probe.
- 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:
- Crank Sensor Input (+).
- Circuit labeled 5:
- Crank 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:
- 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’.