TEST 5: Testing The Ignition Coil's Power (12 V) Circuit

Ignition Coil's Power (12 V) Circuit. Power Transistor Test and Ignition Coil Test 2.4L Nissan Altima (1993-1997)

So far, you have gotten a No spark result on everything you have tested for spark on your Nissan Altima and in the process, you've been narrowing down the list of possible causes.

In this test, you're gonna' verify that the ignition coil is getting power. Because if it isn't, then it won't spark and you've found the cause of the no start and of course no further testing is required.

These are the test steps:

  1. 1

    Select Volts DC mode on your multimeter.

  2. 2

    With the red multimeter test lead probe the wire identified with the number 1 in the photo above.

  3. 3

    Connect the black multimeter test lead to the battery (-) negative terminal.

  4. 4

    Ask your assistant to turn the Key On with the engine Off.

  5. 5

    You should see 10 to 12 Volts on the multimeter if power is present.

Let's interpret your test result:

CASE 1: If your multimeter displayed 12 Volts. This let's you know that the ignition coil is getting power, the next step is to verify that the ignition coil is being fed with the Switching signal that comes from the power transistor. Go to: TEST 6: Testing The Ignition Coil's Switching Signal.

CASE 2: If your multimeter DID NOT display 12 Volts. You must find out why you're missing this voltage. Without this voltage the ignition control module (ICM) nor the ignition coil will work. Resolving this power issue should solve your No Start - No Spark Condition.

TEST 6: Testing The Ignition Coil's Switching Signal

Testing The Ignition Coil's Switching Signal. Power Transistor Test and Ignition Coil Test 2.4L Nissan Altima (1993-1997)

The ignition coil is activated (to spark) by the Switching signal it gets from the Altima's power transistor's Switching signal. Without this signal, the ignition coil won't spark.

This Switching signal can be easily tested with an LED light and I'll show how in this test step.

  1. 1

    Connect the black lead of the LED light to the wire (circuit) identified with the number 2 in the photo.

  2. 2

    Connect the RED lead of LED to the battery positive (+) terminal.

    It is IMPORTANT that it be connected at the battery positive terminal.

  3. 3

    Have your assistant crank the engine while you observe the LED light.

  4. 4

    The LED light will blink on and off the whole time the engine is being cranked.

    NOTE: Don't worry about what the LED light does before or after your helper starts cranking the engine. The only results you're interested in interpreting are the results obtained with the engine cranking.

Let's interpret your test result:

CASE 1: If the LED flashed On and Off. Then the ignition coil is bad, replace it. This also means that the power transistor is GOOD. Replacing the ignition coil will solve your 'no spark no start' condition.

Here's the reason why: If the ignition coil is getting power, which you verified it is in TEST 5 and it is being supplied by the power transistor's Switching signal, which you verified in this test step, then the ignition coil has to spark. Since it didn't spark (in TEST 4) the result you obtained here confirms beyond a shadow of a doubt that the ignition coil is fried.

CASE 2: If the LED DID NOT flash ON and OFF. Re-check all of your connections and retry the test again. If still no light pulses on the test LED, then the next step is to check the power transistor's two circuits for their respective signals, go to: TEST 7: The Power Transistor's Ground Circuit.

Nissan Vehicles:

  • Altima 2.4L
    • 1993, 1994, 1995, 1996, 1997