TEST 1: Testing For Spark
The spark test is the starting point of your troubleshooting on your Nissan Altima or Sentra. It's important to remember that you need to use a spark tester. For the most accurate spark test result I recommend that you use an HEI spark tester.
Whether you have a specific misfire code and you know which ignition coil you need to test or you don't know where to start testing for spark, I suggest you test all four ignition coils.
OK, now to get this show on the road:
Remove the ignition coil from the engine's valve cover.
Attach the HEI spark tester to the coil-On-Plug ignition coil (as shown in the photo above).
Ground the HEI spark tester using a battery jump start to a good Ground point on the engine or directly on the battery negative (-) terminal.
Have your helper crank the engine while you observe the spark tester.
The spark tester should spark.
After noticing the result, which will be either spark or no spark, disconnect the spark tester and put the ignition coil back in place.
Repeat the test for all of the remaining Coil-On-Plug ignition coils on your Nissan Altima or Sentra.
Let's interpret your test results:
CASE 1: The spark tester sparked. This test result tells you that the ignition coil is fine.
Since your Altima (or Sentra) is suffering a cylinder misfire, take a look at the suggestions found here: TEST 6: Carbon Tracks And Other Stuff.
CASE 2: The spark tester DID NOT spark. In about 90% of the time, this test result lets you know that the ignition coil is fried and that replacing it will solve the misfire condition.
But, just to make sure that no other issues exists to cause this no-spark result on this ignition coil, the next step is to make sure that this particular ignition coil is getting power. For this test go to: TEST 2: Testing The Power Circuit (12 Volts).
TEST 2: Testing The Power Circuit (12 Volts)
Testing the power (12 Volts) circuit of the ignition coil on your Nissan Altima or Sentra can be accomplished using a multimeter or a 12 Volt test light.
Power (in the form of 10 to 12 Volts DC) is fed to the ignition coil by the wire labeled with the number 1 in the photo above.
NOTE: It's important that you do not probe the front of the connector (or you run the risk of damaging the female terminal). Use an appropriate tool to back probe or pierce the wire to get to the voltage within the wire. You can see an example of a wire piercing probe here: Wire-Piercing Probe.
These are the test steps:
Remove enough of the plastic tube, that protects the connector's wires, to expose the 4 wires within it for testing.
Disconnect the ignition coil form its electrical connector and set the multimeter to VOLTS DC mode.
Probe the circuit labeled with the number 1 (see photo above) with the red multimeter test lead (using an appropriate tool to pierce the wire or back probe the connector).
Connect the black multimeter test lead to the battery negative (-) terminal.
Have your helper turn the key to the ON position but don't crank or start the engine.
You should see 11-12 Volts on your multimeter if power is present.
Let's see what your test results mean:
CASE 1: The multimeter registered 11-12 Volts (or the test light lit up). This test result confirms that the power circuit is OK and is delivering voltage to the ignition coil.
The next step is to test the Ground circuit. For this test go to: TEST 3: Testing The Ground Circuit.
CASE 2: The multimeter DID NOT register 11-12 Volts (or the test light DID NOT light up). Then the power circuit has a problem. This result eliminates the COP ignition coil as the source of the misfire condition.
The same power circuit is shared by all of the COP ignition coils so this usually means that all 4 ignition coils are not sparking. Although it's beyond the scope of this tutorial, your next step is to restore this missing voltage to get the ignition coils to spark again.