TEST 2: Checking For Spark Directly On The Ignition Coil's Tower (Non-Paired Cylinders)
NOTE: This test step only applies if one or two spark plug wires that do not belong to "paired" cylinders did not spark.
If you've made it this far, your test results show:
- One spark plug wire did not spark out of three (TEST 1).
- Two spark plug wires did not spark, but they're not connected to the same ignition coil (TEST 1).
This lack of spark from the spark plug wire usually indicates one of two things:
- The non-sparking spark plug wire is bad.
- The ignition coil is bad.
To figure out which one's to blame, we'll place the spark tester directly onto the ignition coil tower and check for spark (see the photo above).
Here's what we're looking for:
- If it sparks: The spark plug wire is faulty.
- If it doesn't spark: The ignition coil is malfunctioning.
Time to get started:
- 1
Disconnect the non-sparking spark plug wire from its ignition coil.
- 2
Insert the spark tester in the ignition coil's tower, as shown in the photo above.
- 3
Ground the HEI spark tester with a battery jump start cable directly on the battery negative (-) terminal.
The battery jump-start cable will also hold the spark tester in place. - 4
Have a helper crank the engine while you observe the spark tester.
- 5
The spark tester should spark.
Let's take a look at what your test results mean:
CASE 1: The spark tester sparked. This test result confirms that the spark plug wire (that connects to the ignition coil's tower) is bad.
Replace the spark plug wires as a set, if you have:
- Confirmed that the ignition coil's spark plug wire DOES NOT spark (TEST 1).
- Confirmed that the spark plug wire's ignition coil tower sparked (this test section).
CASE 2: The spark tester DID NOT spark. This test result confirms that the ignition coil is bad.
Replace the ignition coil if you have:
- Confirmed that the ignition coil's spark plug wire DOES NOT spark (TEST 1).
- Confirmed that the spark plug wire's ignition coil tower DID NOT spark (this test section).
TEST 3: Checking For Spark Directly On The Ignition Coil's Tower (Paired Cylinders)
NOTE: This test step only applies if two "paired" spark plug wires did not spark and are connected to the same ignition coil.
Up to this point, your TEST 1 spark test results confirm that the two non-sparking spark plug wires connect to the same ignition coil.
When we don't get spark from "paired" spark plug wires, it usually means one of two things:
- The spark plug wires are bad.
- The ignition coil is probably bad.
In this test section, we're gonna test each coil tower (where the spark plug wires connect) one at a time, using the spark tester to see if we get spark from them.
Here's what we're looking for:
- If both towers spark: The problem lies with the spark plug wires, and they need to be replaced.
- If neither tower sparks: The problem is with the ignition coil itself (we'll still need to make sure it's getting power and an activation signal).
NOTE: Keep in mind, we're testing the two ignition coil towers that belong to the same ignition coil and whose spark plug wires did not spark in TEST 1.
Let's get started!
- 1
Disconnect the non-sparking spark plug wire from its ignition coil tower.
- 2
Insert the spark tester in the ignition coil's tower, as shown in the illustration above.
- 3
Ground the HEI spark tester with a battery jump start cable directly on the battery negative (-) terminal.
The battery jump-start cable will also hold the spark tester in place. - 4
Have a helper crank the engine while you observe the spark tester.
- 5
The spark tester should spark.
- 6
Remove the spark tester and reconnect the spark plug wire back on the ignition coil tower.
- 7
Repeat this test on the other ignition coil tower.
Let's take a look at what your test results mean:
CASE 1: The spark tester sparked in both towers. This test result confirms that the spark plug wires (that connect to the ignition coil) are bad.
Replace the spark plug wires if you have:
- Confirmed that the ignition coil's spark plug wires DO NOT spark (TEST 1).
- Confirmed that both ignition coil towers sparked (this test section).
CASE 2: The spark tester DID NOT spark in only one tower. This test result confirms that the ignition coil is bad.
Replace the ignition coil and the spark plug wires.
CASE 3: The spark tester DID NOT spark in both towers. This test result generally tells you that the ignition coil is bad.
I recommend making sure that this ignition coil tower is getting power and an activation signal. For the first of these two tests, go to: TEST 4: Making Sure The Ignition Coil Is Getting Power.
TEST 4: Making Sure The Ignition Coil Is Getting Power
You don't often see a single ignition coil losing power and shutting down and not creating spark for its spark plug wires –but it does happen every now and then.
In this test section, we're gonna check that the non-sparking ignition coil is getting power (10-12 Volts DC) with a multimeter.
In the photo above, the female terminal marked 1 is the one that delivers this voltage to the ignition coil.
On both the grey and black connectors, female terminal number 1 connects to a black with red stripe (BLK/RED) wire.
If power is available, we'll move on to the next test which is making sure the ignition coil is getting an activation signal from the fuel injection computer.
Let's get started:
- 1
Disconnect the non-sparking ignition coil from its electrical connector.
- 2
Place your multimeter in Volts DC mode.
- 3
Connect the black multimeter test lead to the battery negative (-) terminal.
- 4
Turn the key to the ON position but don't crank or start the engine.
- 5
With the red multimeter test lead and an appropriate terminal probe, probe the female terminal labeled with the number 1 (see the photo above).
Verify that female terminal number 1 corresponds to the BLK/RED wire of the connector.
CAUTION: Gently probe the connector's terminal with the multimeter probe to avoid damaging it (otherwise, you'll need to replace the connector). - 6
Your multimeter should register 10 to 12 Volts DC.
Let's take a look at what your test results mean:
CASE 1: Your multimeter reported 10 to 12 Volts DC. This is the correct and expected test result and tells you that the ignition coil is receiving power.
Your next step is to ensure that the ignition coil is receiving an activation signal. Go to: TEST 5: Checking For The Ignition Coil's Activation Signal.
CASE 2: Your multimeter report 0 Volts DC. This tells you that the ignition coil is not receiving power. Without power, it won't create and deliver spark to its two cylinders.
The most likely cause of these missing 10 to 12 Volts is an open-circuit problem in the BLK/RED of the ignition coil's 4-wire connector.
Your next step is to find and repair the cause of this missing voltage.