In this tutorial I'll explain how to test the ignition system and find out if it's causing a no-start problem or a cylinder misfire problem.
All of the test steps are explained in a step-by-step manner and in plain English.
You'll be able to easily find out if the igniter (ignition control module), the ignition coil, the distributor cap and rotor, or the spark plug wires are behind a no-start problem or a cylinder misfire.
Contents of this tutorial:
- Symptoms Of An Ignition System Problem.
- What Tools Do I Need To Test The Ignition System?
- How Does The Igniter (Ignition Control Module) Work?
- Important Do's And Don't's.
- TEST 1: Testing For Spark At The Spark Plug Wires.
- TEST 2: Testing For Spark At The Distributor Cap.
- TEST 3: Testing For Spark At The Ignition Coil's High Tension Wire.
- TEST 4: Making Sure The Ignition Coil And Igniter Are Getting Power.
- TEST 5: Testing The Ignition Coil For Spark.
- TEST 6: Testing The Ignition Coil's Switching Signal.
- TEST 7: Testing The Igniter's Activation Signal.
- More 2.7L V6 Honda Accord Tutorials.
You can find this tutorial in Spanish here: Cómo Probar El Sistema De Encendido (1995-1997 2.7L Honda Accord) (at: autotecnico-online.com).
APPLIES TO: This tutorial applies to the following vehicles:
- 2.7L V6 Honda Accord: 1995, 1996, 1997.
WIRING DIAGRAM: You can find the ignition system wiring diagram here: Ignition System Wiring Diagram (1995-1997 2.7L Honda Accord).
Symptoms Of An Ignition System Problem
Ignition system problems will generally cause one of two problems:
- The engine will not start due to a lack of spark to all 6 cylinders.
- The engine starts, but runs with a cylinder misfire.
If the engine is misfiring due to an ignition system problem, you'll see one or more of the following trouble codes:
- P0300, P0301, P0302, P0303, P0304, P0305, P0306
You're also gonna' see one or more of the following:
- The check engine light (CEL) will be illuminated on your instrument cluster.
- Your car will idle rough.
- A 'rotten egg' smell may come out of the tailpipe when you drive your car (or mini-van).
- Really bad gas mileage.
- Your vehicle does not pass the emissions test.
What Tools Do I Need To Test The Ignition System?
You don't need any expensive tools to test your Honda ignition system. Here's what you'll need:
- A digital multimeter.
- It doesn't have to be an expensive one, a cheapie one will do just fine.
- A 12 Volt test light.
- An LED light
- I've included a link on what this LED Light looks like and how to make it into a tool here: The LED Light Test Tool And How To Make One.
- A wire piercing probe.
- To see what this tool looks like, click here: Wire Piercing Probe.
- An HEI spark tester.
- This inexpensive spark tester is a MUST have tool to be able to correctly diagnose your Honda vehicle with the info/tests in this article.
- If you want to learn how the HEI spark tester works, click here: The HEI Spark Tester (The Best Spark Tester On The Market).
- A helper to crank the engine.
And lest I forget, a scan tool is not necessary to diagnose and test the Honda distributor type ignition system. All of the testing that you'll be doing will be done without an automotive diagnostic scanner.
How Does The Igniter (Ignition Control Module) Work?
In a nutshell and when the ignition system is working properly, this is what happens when you turn the key to crank and start your Honda:
- 12 Volts are fed first to the ignition coil (when you turn the key to ON and then Crank), and from the coil to the igniter (ignition control module) inside of the distributor.
- The engine starts to turn, which induces the 3 different crankshaft position sensors to start producing and sending their position signals to the fuel injection computer.
- Upon receiving these position signals, the fuel injection computer sends a Triggering signal to activate the igniter.
- The igniter upon receiving this Triggering signal in turn sends a Switching signal to the ignition coil.
- The ignition coil, upon receiving this Switching signal, starts to spark away!
- The Switching signal is just the ‘switching’ ON and OFF of the primary current flowing thru' the Coil by interrupting its path to Ground.
- The primary current is just the name for the 12 Volts that the ignition coil receives.
- The fuel injection computer controls the igniter at start up and at all engine speeds after engine start up, unlike the majority of distributor-type ignition systems where the ignition control module freelances at engine start up.
Important Do's And Don't's
Here are a few suggestions to help you to diagnose your Honda's ignition system free of headaches and/or complications:
- Do not use a regular spark plug instead of a spark tester to test for spark.
- Do not remove the spark plug wire from the spark plug while the engine is cranking to test for spark.
- Keep your hands and fingers away from the rotating distributor shaft when your helper is cranking the engine during the tests.
- Start your diagnostic from TEST 1, do not skip around from test to test.
- Once again, use the recommended/indicated tools for all of your tests.