How Do To A Fuel Injector Noid Light Test (GM 2.2L)

Checking that the fuel injector is getting power and its ON/OFF signal from the PCM (Powertrain Control Module) is a quick and straightforward test on your GM 2.2L equipped vehicle (Chevy Cavalier, S10 Pickup, Pontiac Sunfire, GMC Sonoma).

The good news is, all you need is a Noid light. In this guide, I'll show you exactly how to do it.

With that said, this tutorial builds on the info found in: How To Diagnose Misfire Codes (GM 2.2L). The test procedures shown here apply to GM 2.2L 4-cylinder equipped vehicles like the Chevrolet Cavalier, Pontiac Sunfire, Chevy S10 Pickup, and GMC Sonoma.

Cylinder Misfire Diagnostics: Troubleshooting a cylinder misfire? The following guide is a "must" read:

• How To Diagnose Misfire Codes (GM 2.2L).

The Fuel Injector Noid Light Test

A Noid light is simply a little 12 Volt incandescent light bulb that has two terminals that fit into the fuel injector's connector.

The idea behind the Noid light test is to see if the fuel injector is getting power and the activation signal from the fuel injection computer.

If both are present, the Noid light will flash on and off, while you crank the engine.

If the Noid light doesn't flash on and off (while cranking the engine), then that fuel injector connector is either not getting power or the activation signal (that comes from computer is missing).

This is what you'll need to do:

1. 1

   Locate the fuel injector that you're gonna' test and disconnect it from its electrical connector.
   
   If you have already have a specific misfire code, like: P0301, P0302, P0303, or P0304, you can test that specific fuel injector connector for that specific cylinder that the diagnostic trouble code identifies or you can test them all (which is my recommendation).

2. 2

   Insert the Noid light into the connector, once you have unplugged the fuel injector connector from the fuel injector.
   
   Now, usually Noid lights are sold in a case that will contain several Noid lights for a variety of fuel injector connectors, therefore it's crucial that you use the right one. Using the wrong one will damage the female terminals inside the fuel injector connector. This will create a headache that you don't want to deal with, so be careful.

3. 3

   Have your assistant crank the engine, once everything is set up, stand a safe distance from the engine, but within eye-view of the Noid light.
   
   NOTE: The engine may start or just crank and not start, depending on the issue that you're trying to troubleshoot/diagnose.

4. 4

   You'll get one of three results:
   
   1.) The Noid light will flash ON and OFF the whole time the engine was cranking or running.
   
   2.) The Noid light did not flash ON and OFF at all when the engine was cranked or was running.
   
   3.) The Noid light came On and stayed brightly lit the whole time the engine was cranking or running.

5. 5

   Repeat the above 4 test steps on the other 3 fuel injector connectors. This is a key step, since you'll be able to compare a bad Noid light test result with a good test result in this manner.

OK, let's examine your test results:

CASE 1: The Noid light flashed ON and OFF. This result indicates that the fuel injector is receiving power and the ON/OFF signal from the fuel injection computer. This flashing ON and OFF has to be compared to the results of the other fuel injector Noid light tests AND if the same, you now know beyond a shadow of a doubt that the circuits are OK.

CASE 2: The Noid light DID NOT flash ON and OFF. If this result is obtained from just one fuel injector connector, then it indicates that either power or the ON/OFF signal, from the PCM, is missing.

If all of the fuel injector connectors did not flash ON and OFF, when the engine was cranked, this usually indicates one of several things: a) blown fuel injector fuse, or b) a bad crankshaft position sensor, or c) an ‘open-circuit’ problem in the wiring, or d) a bad PCM, although this is rare.

CASE 3: The Noid light was lit brightly but did not flash ON and OFF. This result is usually a dead giveaway that the PCM is fried. In some rare cases, the circuit that feeds the fuel injector connector with the ON/OFF signal from the PCM is shorted to Ground.

So, before you runoff and buy a new computer, get yourself a wiring diagram for your specific vehicle and check the continuity of the wires between the fuel injector connector and the fuel injection computer.

What Am I Testing With The Noid Light?

OK, here's a little bit of working theory that'll help you to see the ‘why’ of the Noid light test.

Whether you're testing a no-start condition or a Misfire Condition, you'll need to know if the cause of the problem is a lack of fuel. When your GM 2.2L Cavalier (or Sunfire, or Sonoma, or S10 Pick up) does not start, it will be either because of a lack of fuel or spark. The same thing goes for when your GM 2.2L equipped car or pick up is misfiring, that specific engine cylinder isn't contributing to engine power because it either lacks fuel or spark.

Now, since the above two conditions (no-start and misfire) can be caused by any number of things, one of the things that has to be eliminated, from this list of possibles, is the fuel injector not getting power or the ON/OFF switching signal from the vehicle's computer.

Therefore, the purpose of the fuel injector Noid light test is to verify that the fuel injector is receiving power and the ON/OFF switching signal, since without any one of the two, that particular fuel injector will not work. This of course will cause a misfire condition, if this happens to one fuel injector, or a no-start condition if all of the injectors are not getting both of these Signals.

One thing to keep in mind, is that the fuel injector Noid light test does not test for a bad fuel injector. But, is the first step in verifying if the fuel injector is bad or not. For the fuel injector test for your GM 2.2L car or pickup, go down to the list of links at the end of this article.

Which Set Of Noid Lights Should I Buy?

There are lot of fuel injector Noid light sets to choose from and many places to buy them. I'm gonna' make two recommendations to you:

1) Which one to buy:  The fuel injector Noid light kit that I recommend is the Performance Tool W89501 10-Piece Noid And IAC Light Set, and here some reasons why:

• This is one of the most complete Noid light kits on the market. It contains Noid lights for the different fuel injector connectors used on the majority of makes and models, since not all cars use the same fuel injector connector type.
• The plastic case keeps all of the Noid lights organized and safe.
• These tools are durable.
• Price is right.

2) Where to buy:  I recommend buying it from Amazon. At Amazon is where I buy almost all of my tools. Yes, your local AutoZone or O'Reilly auto parts store will have them but at a much higher price.

By clicking on the above images of the different Noid light sets, you'll go to Amazon's site where you can browse to your hearts content.

Related Test Articles

Now, if the Noid light tests on your Chevy (Cavalier, S10 Pickup, or GMC Sonoma, or Pontiac Sunfire) indicated that everything is OK, and yet the car or pickup is still misfiring, the following articles might help:

• GM 2.2L Engine Compression Test.
• GM 2.2L Bad Fuel Injector Test.
• GM 2.2L Misfire Trouble Code Basics.
• How To Test The GM 2.2L Ignition Coil Pack (at: easyautodiagnostics.com).