This article will help you to diagnose a BAD Coil-on-Plug ignition coil that may be causing a misfire condition on your 3.2L 98-99 Isuzu Amigo, Rodeo, Trooper or Honda Passport.
All of the tests are designed to make your troubleshooting as easy and as pain free as possible.
There are two ways to test for a BAD COP ignition coil. The most accurate involves using a spark tester and the other does not. In this article, I cover both.
To help you navigate this article a little easier, here are its contents at a glance:
- Important Tips and Suggestions.
- Ignition Coil Circuit Descriptions.
- Why 3 Wires in the Connector?.
- TEST 1: Testing the Ignition Coils With a Spark Tester.
- TEST 2: Testing the Ignition Coil Without a Spark Tester.
- Which Cylinder is Misfiring?
- I Don't Have Misfire Codes.
- Why the HEI Spark Tester?
Important Tips and Suggestions
TIP 1: The very first thing you need to do, is to find out which cylinder is the one misfiring. For more specific info on how to do this, read the section: Which Cylinder is misfiring.
TIP 2: This article is designed to help you troubleshoot a misfire condition.
TIP 3: Some of the testing requires that you crank the engine as you look for a specific test result, so you need to be careful, stay constantly alert and take all necessary safety precautions.
Since you'll need a helper to crank the engine, I suggest you have him or her wait outside your Isuzu until you need him (or her) to crank the engine. This will avoid having your helper mistakenly cranking the engine while you're still setting up the test.
TIP 4: The most accurate way to test these Coil-on-Plug ignition coils is using an inexpensive HEI spark tester. Do you have to use one to use this info? The answer is NO. You can use any type of spark tester you want, although the results may not be as accurate.
Ignition Coil Circuit Descriptions
This section will give you an overview of the function of the 3 wires that connect to the Coil-on-Plug ignition coil.
If you're needing to test for power or Ground or the COP coil's Triggering Signal, this guide will help you to do it.
All 6 Coil-on-Plug ignition coils on the 3.2L Isuzu engine share the same circuit descriptions. So, it doesn't matter on what engine cylinder the specific Coil-on-Plug ignition coil you're testing is on... the circuits are the same.
Power Circuit: This is the wire identified with the number ? in the image viewer. You can test this circuit by either using a multimeter or a 12 Volt Test Light. Power is available as you as you turn the Key ON, no need to crank the engine while testing this circuit.
Ground Circuit: This is the wire identified with the number ? in the image viewer. You can test this circuit by either using a multimeter or a 12 Volt Test Light. Power is available as you as you turn the Key ON, no need to crank the engine while testing this circuit.
Triggering Signal: This is the wire identified with the number ? in the image viewer. The only way to test this circuit (without an Oscilloscope) is either with an LED Light or an Multimeter that can read Hertz Frequency.
Using an LED Light is the fastest and easiest way to do it... since all you need to look for is the LED light flashing On and Off. A 12 Volt Test Light will not work, and you risk damaging the fuel injection Computer by using one. The LED Light is the safest way to do it.
The LED is connected in the following way: The LED's red lead connects to the wire labeled with the number 1. The LED's black lead connects to the battery's negative terminal. Once the LED is set up, have your helper crank the engine. If the Triggering Signal is present.. the LED will flash On and Off.
Why 3 Wires in the Connector?
Now, in case you're wondering why this COP coil has three wires coming out of the Connector...
Each COP coil (on your 3.2L Isuzu Amigo, Rodeo, Trooper's engine) has an Ignition Control Module (ICM) integrated within itself. This ICM is also and more commonly known as the Power Transistor. One wire provides both the ignition coil and the Power Transistor with Power (12 Volts). The other two wires are for the exclusive use of the Power Transistor. One providing Ground and the other a Triggering Signal.
With the Triggering Signal, the Power Transistor is able to activate the ignition coil part to start sparking away.