Power Transistor Test And Ignition Coil Test 3.3L Nissan (1996-2004)

Testing a no-start problem due to no spark (at any of the spark plug wires) or a misfire condition on your Nissan mini-van or pick up or SUV or the Mercury Villager (with the 3.3L V6 engine) is not difficult at all.

No expensive tools or diagnostic equipment is needed, and this tutorial will show you just how to do it step by step.

With the tests in this article, you'll be able to test and diagnose: A bad power transistor, or a bad ignition coil, or a bad distributor cap, or bad spark plug wires on your Nissan vehicle.

You can find this tutorial in Spanish here: Prueba Del Módulo Y Bobina De Encendido 3.3L Nissan (1996-2004) (at: autotecnico-online.com).

NOTE: You can find the camshaft position sensor test here: How To Test The Camshaft Position Sensor (3.3L V6 Frontier, Pathfinder, Xterra).

The following ignition system wiring diagrams may come in handy:

• Ignition System Wiring Diagram (1999-2004 3.3L Frontier And Xterra).
• Ignition System Wiring Diagram (1996-2000 3.3L Pathfinder) (includes Infiniti QX-4).
• Ignition System Wiring Diagram (1999-2002 3.3L Nissan Quest) (includes Mercury Villager) (at: troubleshootmyvehicle.com).

Symptoms Of A Bad Transistor, Ignition Coil, Spark Plug Wires, Or Dist. Cap

If your Nissan SUV or mini-van is suffering a misfire, the check engine light (CEL) will be on to let you know that YES, there really is something wrong. Here are a couple of other symptoms your vehicle may experience with a misfire condition:

1. Diagnostic trouble codes (DTC) stored in the computer's (PCM) memory:
   • P0300, P0301, P0302, P0303, P0304, P0305, P0306.
2. Misfire that does not light up the check engine light (CEL).
3. No power.
4. Idles rough.
5. Bad gas mileage.
6. Black smoke coming out of the tail-pipe.
7. Rotten egg smell coming out of the tail-pipe.
8. Smell of unburned gasoline coming out of the tail-pipe.
9. Won't pass the state emissions test.

If the power transistor or the ignition coil is bad, then the most common symptom is that your vehicle will CRANK but not START and there will be no spark at any of the spark plug wires.

Basic Nissan Ignition System Theory

To be able to successfully diagnose a misfire or no-start on your Nissan vehicle (whether it' a pick up, SUV, or a mini-van) it'll help to know how spark is created and fed to the engine cylinders. This is what happens in a nutshell when you turn the key and crank the engine:

1. The crankshaft position sensor and camshaft position sensors start to generate and feed their signals to the vehicle's PCM (Powertrain Control Module=Fuel Injection Computer).
2. The PCM uses these signals to know where each piston is at in relation to its combustion cycle and with this info, the PCM knows when to start activating the power transistor, the fuel injectors and a host of other things to get your Nissan vehicle started.
   • The power transistor is the ignition control module (ICM) in the Nissan vehicles.
   • The power transistor is located within the distributor assembly and is part of the cam sensor assembly.
3. So then, after receiving the crank (CKP) and cam (CMP) signals, the PCM sends the power transistor a Triggering signal that tells the power transistor exactly when to activate the ignition coil.
4. The power transistor activates the ignition coil by opening and closing the Primary Current Circuit of the ignition coil and as you may already be aware it's this opening and closing action that makes the ignition coil spark away.
5. The spark created by the ignition coil is fed to the distributor rotor directly by the distributor cap and then from there to each engine cylinder via a spark plug wire.

With the simple and easy tests presented in this test article you'll be able to find the exact cause of your Nissan vehicle's misfire or no-start condition (if it's ignition system related) and in the process save time and money.

Ignition System Diagnostic Manual Download

Testing a no-start problem or a misfire due to an ignition system problem is not hard.

If you'd like to have access to a wiring diagram, ignition component connector pin-outs, and the entire testing procedure (for a no-start or a misfire problem) in one place, then take a look at the following diagnostic manuals in downloadable PDF format:

What Tools Do I Need To Test The Ignition System?

Although the tests in this article are easy and simple, you do need some specific tools to perform them with. Here's the list:

1. An HEI spark tester
   • This inexpensive spark tester is a MUST have tool to be able to correctly diagnose the ignition system on your Nissan vehicle with the info and tests in this article (don't have an HEI spark tester? Need to buy one? You can buy it here: OTC 6589 Electronic Ignition Spark Tester).
   Don't use a regular spark plug instead of a spark tester.
2. Battery jump start cables.
3. A digital multimeter that can read Hertz (Hz) frequency.
   • Without a multimeter that can read Hertz frequency, you won't be able to accomplish some of these tests. (don't have a digital multimeter that can read Hertz frequency? Click here to see my recommendations: Buying A Digital Multimeter For Automotive Diagnostic Testing).
4. A helper.
   • You'll need someone to help you crank the engine while you perform the tests in the engine compartment.
5. A repair manual.
   • For whatever remove and replace info you'll need that is not covered by this article.

Power Transistor/Cam Sensor Assembly Circuit Descriptions

There are 6 wires coming out of the main distributor connector. This connector connects to the power transistor/cam sensor assembly that's located within the distributor.

Now, don't worry, you don't need to test all of them to diagnose this ignition system. Below are the circuit descriptions of all six wires (circuits):

• Circuit labeled 1
  • Triggering Signal for Power Transistor. This Signal comes from the PCM.
• Circuit labeled 2
  • Ground Circuit for the Power Transistor.
• Circuit labeled 3
  • Camshaft Position Sensor Signal - 120° REF Signal.
• Circuit labeled 4
  • Camshaft Position Sensor Signal -1° POS Signal.
• Circuit labeled 5
  • Camshaft Position Sensor Power (12 Volts).
• Circuit labeled 6
  • Camshaft Position Sensor Ground.

NOTE: The photo above is of the Nissan Pathfinder's 6-wire connector. If your vehicle is not a Pathfinder (or QX-4), the colors of the wires will be different. This is no cause for concern because the circuit descriptions are the same.

The following ignition system wiring diagrams include the distributor's 6-wire connector circuits:

• Ignition System Wiring Diagram (1999-2004 3.3L Frontier And Xterra).
• Ignition System Wiring Diagram (1996-2000 3.3L Pathfinder) (includes Infiniti QX-4).
• Ignition System Wiring Diagram (1999-2002 3.3L Nissan Quest) (includes Mercury Villager) (at: troubleshootmyvehicle.com).

Ignition Coil Circuit Descriptions

The other connector has two wires coming out of it and both of these go directly to the ignition coil inside of the distributor. Here are their circuit descriptions:

1. Circuit labeled 7
   • Power (12 V) Circuit.
2. Circuit labeled 8
   • Switching Signal output to the PCM.

NOTE: The photo above is of the Nissan Pathfinder's 2-wire connector. If your vehicle is not a Pathfinder (or QX-4), the colors of the wires will be different. This is no cause for concern because the circuit descriptions are the same.

The following ignition system wiring diagrams include the distributor's 2-wire connector circuits:

• Ignition System Wiring Diagram (1999-2004 3.3L Frontier And Xterra).
• Ignition System Wiring Diagram (1996-2000 3.3L Pathfinder) (includes Infiniti QX-4).
• Ignition System Wiring Diagram (1999-2002 3.3L Nissan Quest) (includes Mercury Villager) (at: troubleshootmyvehicle.com).