TEST 3: Testing For Spark At The Ignition Coil
In this test section, we're gonna' check for spark directly on the ignition coil's tower.
It can be a bit tricky to hold the spark tester on the ignition coil tower as the engine is being cranked, so I'm gonna' suggest that you use black electrical tape to hold/attach them together.
If you get spark, then you can conclude that the reason you got no spark at any of the spark plug wires (in TEST 1) is because the distributor rotor and cap are bad.
If you don't get spark, from the ignition coil's tower, then the next step is to make sure that the ignition coil is getting power (in TEST 4).
IMPORTANT: This test requires that the ignition coil be tested with the distributor cap off of the distributor. It's important that this test be done with a spark tester attached to the ignition coil. In other words, don't crank the engine without the spark tester attached to the ignition coil's tower.
These are the test steps:
Remove the distributor cap.
Place the spark tester directly on the ignition coil's tower (see image 2 of 3 and image 3 of 3).
NOTE: Attach the spark tester to the ignition coil's tower with black electrical tape (see image 3 of 3). This will prevent the spark tester from falling off the tower as the engine is cranked.
Have your helper crank the engine once again while (1) you watch for spark jumping across the air gap of the spark tester and (2) that the distributor rotor is turning.
You're gonna' get one of the 3 results:
1.) Spark and the distributor rotor turns.
2.) No spark and the distributor rotor DOES NOT turn.
3.) No spark and the distributor rotor DOES turn.
Let's analyze your test result below:
CASE 1: You got spark and the distributor rotor turns. This is the correct and expected test result.
You can conclude that the distributor cap and the distributor rotor are bad and need to be replaced if you have:
- Confirmed that none of the spark plug wires are sparking (TEST 1).
- Confirmed, in this test section, that the ignition coil is sparking.
CASE 2: You got NO spark and the distributor rotor DOES NOT turn. This is usually the result of a broken timing belt.
Another cause that I've seen quite a bit, is that the camshaft has broken in two, although the timing belt does not break. Inspect the timing belt and/or remove the valve cover to see if the entire camshaft is rotating as one piece.
Here's why: The crankshaft rotates the distributor rotor via the timing belt. How? Well, the distributor is physically connected to the camshaft. The camshaft is rotated by the crankshaft via the timing belt. A broken timing belt won't rotate the camshaft and by extension, the distributor rotor. And if the distributor shaft does not rotate, the computer will not receive the CYP sensor signal and the ignition system will not work to produce spark.
CASE 3: You got NO spark and the distributor rotor DOES turn. Then further testing is required to see if the problem is due to a bad igniter (ignition control module) or a bad ignition coil.
Your next step is to make sure that both the igniter and the ignition coil are getting power (12 Volts). Go to: TEST 4: Making Sure The Ignition Coil And Module Are Getting Power.
TEST 4: Making Sure The Ignition Coil And Module Are Getting Power
The ignition coil and the igniter need power to function, since without it, the ignition system is not going to create spark.
Both the ignition coil and the igniter get power from the same circuit (wire).
The wire that supplies this power (in the form of 10 to 12 Volts) is the black with yellow stripe (BLK/YEL) wire that the arrow in the photo above is pointing to.
These are the test steps:
Disconnect the distributor from its electrical connector.
Place your multimeter in Volts DC mode.
Connect the red multimeter lead to the female terminal that connects to the BLK/YEL wire in the photo above.
Connect the black multimeter lead to the battery negative (-) terminal.
Have your assistant turn the key to ON.
Your multimeter should register 10 to 12 Volts DC.
Let's take a look at your test result:
CASE 1: The multimeter registered 10 to 12 Volts. This is the correct test result and it confirms that both the igniter (ignition control module) and the ignition coil are receiving power.
The next test is to see if the ignition coil is getting an activation signal. For this test go to: TEST 5: Testing The Ignition Coil's Switching Signal.
CASE 2: The multimeter DID NOT register 10 to 12 Volts. Without power, the ignition coil will not fire spark.
Your next step is to find out why these 10 to 12 Volts are missing and resolve the issue.