How to test the GM ignition control module?

You can find this tutorial in Spanish here: Cómo Probar El Módulo de Encendido GM 4.3L, 5.0L, 5.7L (1995-2005) (at: autotecnico-online.com ). Generally, when the ICM or the ignition coil fails, your GM car or truck will Crank but NOT START.

What are the wires in the ignition module?

The ignition control module (ICM) has 4 wires coming out of it. Below are the descriptions of what each circuit does. Each circuit is identified by a letter, and this is the same letter that you will find on the ignition module’s connector. Power (12 V) Circuit. Ignition Control (IC) Signal. Engine Ground Circuit. Switching Signal Circuit.

What was the ignition module for a 1996 GMC c2500?

1996 GMC C1500, C2500, C3500 Pick Up. 1996 GMC K1500, K2500, K3500 Pick Up. All of the information you need to diagnose a misfire or a no-start problem (caused by the ignition coil, the ignition module, or the crankshaft position sensor).

How does the Ignition Control Module ( ICM ) work?

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 control module (ICM).

Can a GMC Safari ignition control module wear out?

The ICM can wear out over time and cause misfires. Sometimes the ICM is fine, but it overheats because there is not enough grease under it to help it dissipate the extra heat. This video shows you how to replace the ICM ignition control module on your GMC Safari or Astro van. It’s an easy job to do. The new ICM costs around $50. Loading…

What happens if you have a bad ignition control module?

A faulty ignition control module can cause a number of problems. 1. Check engine light is on: The ECM monitors all parts of the vehicle that could affect emissions. This includes the ignition system. If it determines the ignition module has caused a problem with the system, it will turn on the check engine light.

How many wires does the ignition module have?

Let’s take a look at your test results: CASE 1: If you got 10 to 12 Volts. This result lets you know that the Ground circuit is OK. The next step is to test the Switching Signal that the ICM feeds the ignition coil, go to: TEST 3: Testing For The Ignition Coil Switching Signal.

Is the ignition coil and ignition module the same circuit?

Both, the ignition module and ignition coil get power (10 to 12 Volts) from the same circuit, so by testing one component you’re also testing the other. IMPORTANT: It’s critical to start here at TEST 1 and then go to the next indicated test (s) to successfully use this info and to diagnose your GM ICM or ignition coil.

What kind of signal does the ignition module need?

OK, moving on along… for the ignition module to create this Switching signal, it needs to receive a C ran k shaft P osition (CKP) sensor signal (this signal is usually referred to as the Triggering signal and in GM service literature it’s known as the 3X or 7X CKP signal).

Where does 12 volt ignition coil get power?

If your car uses a 12 volt battery, the 12 volts you put into the primary side of the coil will exit the secondary side as 30,000 volts! Furthermore, where does ignition coil get power?

How does the ignition control module ( PCM ) work?

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 control module (ICM). The really cool thing about this type of ignition system is that all of these signals ( IC Signal and the Switching Signal) can be tested easily with some very simple tools.

How does the GM 4 pin ignition system work?

GM 4-Pin HEI Electronic Ignition Control Module Wiring Connections/Diagram with the Cube-Shaped 3-Wire Inductive Proximity Sensor This ignition system operates with full 12 volts. This is a thoroughly tested, researched and proven reliable ignition system invented by Brian Miller for ordinary lawn & garden engines and competition pulling engines.

Where is the CKP sensor on the ignition module?

As you can see, the CKP sensor signal is critical for the ECM and ignition control module to start sparking the Igntion coils at START UP and at all engine speeds. The CKP sensor is located on the block.

How does the crank sensor work on a GMC 4.3L?

Below, in a nutshell, is how the crankshaft position sensor works in your 4.3L, 5.0L, and 5.7L Chevrolet or GMC (or Olds, Cadillac) Pick Up or SUV: When you turn the key and start cranking the engine the crank sensor gets 12 Volts on Circuit A and Ground on Circuit B.

How to troubleshoot a no start GM 4.3L?

How To Troubleshoot A No Start (GM 4.3L, 5.0L, 5.7L). CASE 2: The multimeter DID NOT register the ON/OFF voltage signal as you turned the engine with the ratchet. This test result usually confirms that the crankshaft position sensor is bad and needs to be replaced.

What are the symptoms of a bad ignition module?

Symptoms Of A Bad Ignition Module And Ignition Coil Generally, when the ICM or the ignition coil fails, your GM car or truck will Crank but NOT START. Specifically, the ignition coil will not spark.

What happens when the ICM fails on a GM car?

Generally, when the ICM or the ignition coil fails, your GM car or truck will Crank but NOT START. Specifically, the ignition coil will not spark.

How to test the GM ignition control module?