The power transistor in your 1998, 1999, 2000, 2001, 2002, 2003, 2004 2.4L Nissan Frontier or 2001-2004 2.4L XTerra is the Ignition Control Module (ICM) of the ignition system.
The power transistor is the one that activates the ignition coil to spark and if this bad boy (the power transistor) goes bad, your Frontier or XTerra won't start.
In this article, I'll show you a very easy way to troubleshoot the power transistor to find out if it's bad or not. This is an On Car test which does not require expensive Scan Tools or other expensive/exotic diagnostic equipment.
To help you navigate this article a little easier, here are its contents at a glance:
- Important Tips And Suggestions.
- IGNITER TEST 1: Verifying The Power Transistor Is Getting Power.
- IGNITER TEST 2: Verifying The Power Transistor's Triggering Signal.
- IGNITER TEST 3: Verifying The Ignition Coil's Switching Signal.
- How Does The Igniter Work?
You can find this tutorial in Spanish here: Cómo Probar el Módulo de Encendido (1998-2004 2.4L Frontier, Xterra) (at: autotecnico-online.com).
Important Tips And Suggestions
TIP 1: TEST 1 and TEST 2 require that you do them while the engine is cranking, so you have to take all necessary safety precautions. Think safety all of the time.
TIP 2: The battery in your Nissan Frontier or XTerra must be fully charged so that the engine can reach its maximum cranking RPMs for these tests to be effective.
TIP 3: This power transistor test assumes that your Frontier or XTerra Does Not Start due to a Lack of Spark. If your vehicle does not start but you do have spark, this article will not help you.
TIP 4: The igniter (power transistor) is part of the cam sensor and is inside the distributor.
TIP 5: If the igniter (power transistor) is fried, you'll have to replace the entire distributor, since it's not sold separately.
IGNITER TEST 1: Verifying The Power Transistor Is Getting Power
If you haven't tested the ignition coil first... please do so first (it's important that you test the ignition coil first and make it's not sparking!).
The test for the ignition coil can be found here: 2.4L Nissan Frontier, XTerra Ignition Coil Test (98-04) (if the ignition coil is sparking, then the power transistor is OK and not defective).
OK, to get this show on the road, the very first thing to do is to make sure that the distributor is getting power (12 Volts).
Without these 12 Volts, nothing's gonna work.
Alright, this is what you'll do:
Place your multimeter in Volts DC mode.
With the red multimeter test lead, probe the wire labeled with the number 2, in the photo in the image viewer.
Next, ground the black multimeter test lead directly on the battery negative (-) terminal.
Now, turn the Key on (you don't have to crank the engine) and notice the multimeter's voltage reading.
Your multimeter should display 12 Volts DC.
Let's take a look at what your test result means:
TEST RESULT 1: Your multimeter registered 12 Volts. This is good and confirms that the distributor (mainly the components inside) is getting power.
The next step is check that the power transistor is being fed a Triggering signal from the fuel injection computer. Go to: IGNITER TEST 2: Verifying The Power Transistor's Triggering Signal.
TEST RESULT 2: Your multimeter DID NOT register 12 Volts. Recheck your multimeter connections and retest. If you still don't see 12 Volts, then this result eliminates the power transistor as bad since without power the components that work in conjuction with the power transistor will not work and indirectly affect the power transistor.
Although it's beyond the scope of this article to troubleshoot this missing voltage, finding the cause of these missing 12 Volts will solve your 'no spark no start' condition on your 2.4L Nissan Frontier or Xterra.