How To Test The Ignition Coil And Power Transistor (1993-1998 3.0L Nissan Quest)

TEST 4: Testing The Ignition Coil For Spark

We're going to place the spark tester directly in the ignition coil's tower and then have a helper crank the engine (just as it's shown in the photo above).

The purpose of this test is to make sure that the ignition coil is sparking.

If the ignition coil sparks then you can conclude that the reason why the high tension wire did not spark in TEST 3 is because it is defective.

If the ignition coil does not spark then your next step is to go to TEST 5.

These are the test steps:

1. 1

   Remove the high tension wire that connects to the igntion coil.

2. 2

   Place the HEI spark tester directly on the ignition coil's tower as shown in the photo above.

3. 3

   Connect the spark tester to the battery negative (-) terminal with a battery jump start cable.

4. 4

   Have your helper crank the engine as you hold the HEI spark tester in place.

5. 5

   The HEI spark tester should spark.

Let's analyze your test results:

CASE 1: The spark tester sparked. This is the correct test result.

You can conclude that the ignition coil's high tension wire is bad only if you have:

• Confirmed that all of the spark plug wires are not sparking (TEST 1).
• Confirmed that ignition coil's high tension wire does not spark (TEST 3).
• Confirmed that the ignition coil's tower does spark (TEST 4).

Replacing the spark plug wires as a set should solve the no-start problem on your 3.0L Nissan Quest (Mercury Villager).

CASE 2: The spark tester DID NOT spark. Then the next step is to make sure that the ignition coil is getting 10 to 12 Volts DC. For this test go to: TEST 5: Making Sure The Ignition Coil Is Getting 12 Volts.

TEST 5: Making Sure The Ignition Coil Is Getting 12 Volts

The ignition coil needs 10 to 12 Volts to function. If this voltage is missing then the ignition coil will not spark.

So in this test section we're going to make sure that this voltage is present on the wire labeled with the number 2 in the photo above.

On the 1993-1995 3.0L Nissan Quest (Mercury Villager) this wire is a white with red stripe (WHT/RED) wire.

On the 1995-1998 3.0L Nissan Quest (Mercury Villager) this wire is a brown (BRN) wire.

If power is present then our next test is to make sure that the ignition coil is getting an activation signal from the power transistor.

Let's get started:

1. 1

   Select Volts DC mode on your multimeter.

2. 2

   Disconnect the ignition coil from its electrical connector.

3. 3

   Turn the key ON but don't crank the engine.

4. 4

   Probe the female terminal (of the connector) that connects to the BRN wire.

5. 5

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

6. 6

   You should see 10 to 12 Volts on the multimeter.

Let's find out what your test result means:

CASE 1: 10 to 12 Volts are present in the BRN wire. This is the correct test result and it lets you know that the ignition coil is getting power.

Since the ignition coil does not fire spark, the next step is to check that the ignition coil is receiving an activation signal. This activation signal comes from the power transistor. For this test go to: TEST 6: Testing The Ignition Coil's Activation Signal.

CASE 2: 10 to 12 Volts ARE NOT present in the BRN wire. Without power the ignition coil will not fire spark.

This lack of spark will be caused by one of the following:

• An open-circuit problem in the BRN wire between the ignition coil's connector and the ignition switch.
• A defective ignition switch.