How To Test The GM Ignition Control Module (1995-2005)

This is 1 of the easiest GM ignition control modules to test. This article will take you lot step by step through the whole process of diagnosing and troubleshooting a bad ignition control module and ignition coil.

The ignition control module (ICM) and ignition gyre tests in this commodity assume that your vehicle is cranking simply non starting due to a NO-SPARK condition. If yous're GM auto or truck starts and runs, this commodity volition not help you.

Now, if you need to test a misfire status, or exam the spark plug wires, or distributor cap on this type of GM ignition system, click here: How To Exam A Misfire / No-Spark No-Start Condition GM iv.3L, 5.0L, five.7L Distributor Ignition System (1996-2004).

Since so many things tin crusade your vehicle to not start (similar a bad fuel pump, etc.), the post-obit tutorial may exist of help to you lot:

  • How To Troubleshoot A No Offset (GM iv.3L, 5.0L, 5.7L) (at: troubleshootmyvehicle.com).

NOTE: The following ignition arrangement excursion diagram may be of assistance: Ignition System Excursion Diagram (1996-1999 Chevy/GMC Pick Up And SUV).

At the end of this tutorial I've included a list of other tutorials that volition assist you lot diagnose a cranks simply does non start condition (in case it'south not ignition system related).

En Español You tin observe this tutorial in Spanish here: Cómo Probar El Módulo De Encendido GM four.3L, 5.0L, v.7L (1995-2005) (at: autotecnico-online.com).

Symptoms Of A Bad Ignition Module And Ignition Roll

Generally, when the ICM or the ignition curlicue fails, your GM car or truck volition crank just not showtime. Specifically, the ignition scroll will not spark.

For this particular reason (and earlier you follow the exam procedures in this tutorial), yous need to verify that the ignition coil IS Non sparking by connecting a spark tester directly on the ignition coil's tower and cranking the engine.

This is a pretty easy test, merely it must be done with a spark tester. You lot can find the exam steps hither: Exam 4: Spark Test At Ignition Roll Tower (this examination belong to this tutorial: How To Exam A Misfire / No Spark-No Kickoff Condition (4.3L, 5.0L, 5.7L 96-04)).

Notation: When the ignition ringlet or the ICM start to neglect, they don't always crusade a cranks but does Non start status, since sometimes these components can fail intermittently. In this scenario, your vehicle will offset and run most of the time, simply every now and and so information technology won't. If this is the case, you'll have to wait till the car or truck does not start to use the tests in this commodity.

What Tools Do I Need?

You don't need a whole lot of stuff, heck, you don't even need a scan tool (tho' a browse tool is important to take, but not for this article)! Here is what you lot're gonna' need to effectively use the information in this article:

  1. A multimeter (don't accept a digital multimeter? Need to purchase one? Click hither to see my recommendations: Buying A Digital Multimeter For Automotive Diagnostic Testing).
  2. An LED light. To see a photo of this tool click here: Abe's LED Light.
  3. A 12 Volt exam low-cal.
  4. A helper to crank the engine.
  5. A wire piercing probe. This tool is a time saver. If you need to run across what this tool looks similar, click here: Wire Piercing Probe.

As yous can come across/read, these are just basic tools, nothing fancy, extravagant or EXPENSIVE.

Bones Operating Theory

Hither is a niggling background information to help you diagnose the ignition command module (ICM) or the ignition coil. In a nutshell, when your plow the key and offset cranking the engine:

  1. Power in the form of 12 Volts flows into the crankshaft position (CKP) sensor, the ignition control module (ICM), the ignition coil, amid several things.
  2. The crankshaft position (CKP) sensor starts to create its CKP signal, which it sends to the PCM.
    • The crankshaft position sensor is a Hall Effect type sensor and produces a digital (ON/OFF) indicate that can exist seen with an LED or an oscilloscope. On an oscilloscope, it produces a digital foursquare waveform.
  3. The PCM, upon receiving the crank signal (forth with other sensor input signals) start to do its little vocal and dance and sends the ignition command module (ICM) a indicate called the IC point (IC=Ignition Command).
  4. With this IC signal, the ignition module starts to activate the ignition ringlet to get-go sparking with a Switching bespeak.
    • Equally you lot're probably already aware, the Switching signal is but a term that describes the switching 'ON and OFF' of the Principal Current's path to Ground (the Primary Current refers to the 12 Volts supplied to the ignition coil).

If everything is working properly, the engine will start. Now, the important thing to know is that the PCM controls the creation of spark from the get-go (crank up) and at all engine speeds thru' the ignition command module (ICM). The really absurd matter almost this type of ignition system is that all of these signals (IC indicate and the Switching bespeak) can be tested easily with some very simple tools.

Where To Purchase The ICM And Ignition Coil And Save

The following links will aid yous comparing shop for the factory original ignition command module and ignition coil:

Not sure if the ignition organization components above fit your particular GM vehicle? Don't worry, once yous get to the site, they'll make sure they fits and if they don't, they'll find y'all the right ones.

Ignition Control Module (ICM) Circuit Descriptions

Ignition Control Module (ICM) Circuit Descriptions. How To Test The GM Ignition Control Module (1995-2005)

The ignition command module (ICM) has four wires coming out of it. Below are the descriptions of what each excursion does. Each circuit is identified by a letter of the alphabet, and this is the same letter that y'all will find on the ignition module's connector.

  • Circuit labeled A -Pink Wire:
    • Power (12 V) Circuit.
  • Circuit labeled B -White Wire:
    • Ignition Control (IC) Bespeak.
  • Circuit labeled C -Blackness with White stripe Wire:
    • Engine Ground Excursion.
  • Circuit labeled D -White with Black stripe Wire:
    • Switching Signal Circuit.

The following ignition organisation circuit diagram may be of help: Ignition System Circuit Diagram (1996-1999 Chevy/GMC Option Upwards And SUV).

Ignition Coil Circuit Descriptions

Ignition Coil Circuit Descriptions. How To Test The GM Ignition Control Module (1995-2005)

The ignition ringlet on your car or truck may have or may not have three wires coming out of it. Whether information technology does or doesn't doesn't matter, the info in this test article nevertheless applies. Below are the descriptions of what each circuit does. Each circuit is identified by a letter, and this is the aforementioned letter that you will find on the ignition coil'south connector.

  • Circuit labeled A -Pink Wire:
    • Power (12 V) Circuit.
  • Circuit labeled B -White Wire:
    • Tach Signal for the tachometer in the musical instrument cluster if equipped.
  • Circuit labeled C -White with Black stripe Wire:
    • Switching Signal Circuit. This wire (excursion) comes from the ignition module.

The following ignition arrangement circuit diagram may be of assist: Ignition System Excursion Diagram (1996-1999 Chevy/GMC Pick Upward And SUV).

Ignition System Diagnostic Transmission Download

If you'd like to take access to a wiring diagram, ignition component connector pin-outs, and the entire testing procedure in one identify, and so take a look at the following diagnostic manuals in downloadable PDF format:

Chevrolet/GMC C/K Series Full Size Option Ups:

1996 Chrevrolet/GMC Full Size Pick Ups PDF
Engines: iv.3L, v.0L, 5.7L, 7.4L
1996 Full Size Pick Up
Ignition System No-First Diagnostic Transmission

$3.99 USD

All of the information you demand to diagnose a misfire or a no-outset trouble (acquired by the ignition coil, the ignition module, or the crankshaft position sensor).

Diagnostic manual comes with:

  • Wiring diagrams.
  • Component pin outs.
  • Connector pin outs.
  • Firing orders.
  • Complete step-by-footstep testing instructions.

The illustrations in the diagnostic manual are printer friendly! Applies to:

  • 1996 Chevrolet C1500, C2500, C3500 Pick Upwards.
  • 1996 Chevrolet K1500, K2500, K3500 Choice Upwardly.
  • 1996 GMC C1500, C2500, C3500 Pick Upwardly.
  • 1996 GMC K1500, K2500, K3500 Pick Up.
1997 Chrevrolet/GMC Full Size Pick Ups PDF
Engines: 4.3L, five.0L, v.7L, vii.4L
1997 Full Size Pick Up
Ignition Organization No-Get-go Diagnostic Manual

$3.99 USD

All of the information you lot need to diagnose a misfire or a no-start trouble (caused past the ignition whorl, the ignition module, or the crankshaft position sensor).

Diagnostic manual comes with:

  • Wiring diagrams.
  • Component pin outs.
  • Connector pivot outs.
  • Firing orders.
  • Complete step-by-step testing instructions.

The illustrations in the diagnostic transmission are printer friendly! Applies to:

  • 1997 Chevrolet C1500, C2500, C3500 Choice Upwardly.
  • 1997 Chevrolet K1500, K2500, K3500 Pick Up.
  • 1997 GMC C1500, C2500, C3500 Selection Up.
  • 1997 GMC K1500, K2500, K3500 Pick Up.
1998 Chrevrolet/GMC Full Size Pick Ups PDF
Engines: 4.3L, five.0L, 5.7L, 7.4L
1998 Full Size Pick Upwards
Ignition System No-Showtime Diagnostic Transmission

$three.99 USD

All of the information you lot need to diagnose a misfire or a no-start problem (caused by the ignition coil, the ignition module, or the crankshaft position sensor).

Diagnostic transmission comes with:

  • Wiring diagrams.
  • Component pin outs.
  • Connector pin outs.
  • Firing orders.
  • Complete step-by-step testing instructions.

The illustrations in the diagnostic manual are printer friendly! Applies to:

  • 1998 Chevrolet C1500, C2500, C3500 Pick Up.
  • 1998 Chevrolet K1500, K2500, K3500 Pick Upwardly.
  • 1998 GMC C1500, C2500, C3500 Pick Upward.
  • 1998 GMC K1500, K2500, K3500 Option Up.
1999 Chrevrolet/GMC Full Size Pick Ups PDF
Engines: 4.3L, 5.0L, 5.7L, vii.4L
1999 Full Size Pick Up
Ignition System No-Commencement Diagnostic Manual

$3.99 USD

All of the data you demand to diagnose a misfire or a no-get-go trouble (caused by the ignition coil, the ignition module, or the crankshaft position sensor).

Diagnostic transmission comes with:

  • Wiring diagrams.
  • Component pin outs.
  • Connector pin outs.
  • Firing orders.
  • Complete stride-by-step testing instructions.

The illustrations in the diagnostic manual are printer friendly! Applies to:

  • 1999 Chevrolet Silverado, C1500, C2500, C3500 Selection Upwards.
  • 1999 Chevrolet K1500, K2500, K3500 Pick Upwardly.
  • 1999 GMC Sierra, C1500, C2500, C3500 Pick Up.
  • 1999 GMC K1500, K2500, K3500 Pick Up.
2000 Chrevrolet/GMC Full Size Pick Ups PDF
Engines: 4.3L, 5.7L, 7.4L
2000 Total Size Choice Up
Ignition Arrangement No-Start Diagnostic Transmission

$3.99 USD

All of the information you need to diagnose a misfire or a no-starting time problem (caused past the ignition coil, the ignition module, or the crankshaft position sensor).

Diagnostic manual comes with:

  • Wiring diagrams.
  • Component pin outs.
  • Connector pin outs.
  • Firing orders.
  • Consummate step-by-pace testing instructions.

The illustrations in the diagnostic manual are printer friendly! Applies to:

  • 2000 Chevrolet Silverado, C2500, C3500 Choice Up.
  • 2000 Chevrolet K1500, K2500, K3500 Pick Up.
  • 2000 GMC Sierra, C2500, C3500 Option Up.
  • 2000 GMC K1500, K2500, K3500 Pick Up.

Chevrolet Express Van and GMC Savana Van:

1996-1999 Chrevrolet Express/GMC Savana PDF
Engines: 4.3L, 5.0L, v.7L, vii.4L
1996-1999 Express/Savana
Ignition System No-First Diagnostic Manual

$3.99 USD

All of the information you need to diagnose a misfire or a no-beginning problem (caused by the ignition gyre, the ignition module, or the crankshaft position sensor).

Diagnostic manual comes with:

  • Wiring diagrams.
  • Component pin outs.
  • Connector pivot outs.
  • Ignition system component part numbers.
  • Firing order.
  • Complete step-by-step testing instructions.

The illustrations in the diagnostic manual are printer friendly! Applies to:

  • 1996-1999 Chevrolet Express Van.
  • 1996-1999 GMC Savana Van.
2000 Chrevrolet Express/GMC Savana PDF
Engines: iv.3L, 5.0L, five.7L, seven.4L
2000 Express/Savana
Ignition System No-Showtime Diagnostic Manual

$3.99 USD

All of the information yous need to diagnose a misfire or a no-start problem (acquired by the ignition coil, the ignition module, or the crankshaft position sensor).

Diagnostic manual comes with:

  • Wiring diagrams.
  • Component pin outs.
  • Connector pivot outs.
  • Ignition system component office numbers.
  • Firing order.
  • Complete step-past-step testing instructions.

The illustrations in the diagnostic manual are printer friendly! Applies to:

  • 2000 Chevrolet Limited Van.
  • 2000 GMC Savana Van.

Chevrolet Tahoe and GMC Yukon:

1996-2000 Chrevrolet Tahoe/GMC Yukon PDF
Engines: 5.7L
1996-2000 Tahoe/Yukon
Ignition System No-Offset Diagnostic Manual

$3.99 USD

All of the data yous need to diagnose a misfire or a no-start trouble (caused by the ignition coil, the ignition module, or the crankshaft position sensor).

Diagnostic transmission comes with:

  • Wiring diagram.
  • Component pin outs.
  • Connector pin outs.
  • Firing guild.
  • Ignition arrangement component part numbers.
  • Firing order.
  • Complete step-by-footstep testing instructions.

The illustrations in the diagnostic manual are printer friendly! Applies to:

  • 1996-2000 Chevrolet Tahoe (4x2 and 4x4).
  • 1996-2000 GMC Yukon (4x2 and 4x4).

Chevrolet and GMC Suburban:

1996-1999 Chrevrolet/GMC Suburban PDF
Engines: 5.7L, 7.4L
1996-1999 Suburban
Ignition System No-Starting time Diagnostic Transmission

$3.99 USD

All of the information you need to diagnose a misfire or a no-start trouble (caused by the ignition roll, the ignition module, or the crankshaft position sensor).

Diagnostic transmission comes with:

  • Wiring diagram.
  • Component pivot outs.
  • Connector pin outs.
  • Ignition system component part numbers.
  • Firing club.
  • Complete step-by-step testing instructions.

The illustrations in the diagnostic manual are printer friendly! Applies to:

  • 1996-1999 Chevrolet Suburban (4x2 and 4x4).
  • 1996-1999 GMC Suburban (4x2 and 4x4).