TEST 5: Testing The Ignition Coil For Spark
IMPORTANT: This test requires that you crank the engine with the ignition coil's high tension wire disconnected from the distributor cap! The ignition coil has to be connected to a spark tester for this test. Do not crank the engine without a spark tester or the high tension wire connected to the ignition coil, or you run the risk of damaging the ignition coil.
OK, on with this lie with call life:
- Disconnect the high tension wire from the ignition coil.
- Place the HEI spark tester into the ignition coil tower.
- You have to hold the spark tester in place with battery jumper cables (as shown in the photos in the image viewer).
- Have your helper crank the engine while you hold and observe if spark jumps across the HEI spark tester.
You're only get one of two results which are: spark or No spark jumping across the gap of the HEI spark tester.
CASE 1: If you got spark. This result indicates that the ignition coil is good. So, the result of your NO spark condition is due to the ignition coil's high tension wire being bad. Replace all of the spark plug wires as a set.
Here's why: Over time the spark plug wires age and stop transmitting spark. So if in this test result your spark tester sparked (when testing for spark directly at the ignition coil tower) than he can correctly conclude that the ignition coil's high tension wire is defective and not able to transmit spark to the distributor cap anymore
CASE 2: If you got No spark. Then we have to dig a little deeper to find out what the problem is. The next step is to see if the ignition coil and igniter are getting power. For this test go to: TEST 4: Testing The Ignition Coil & Igniter For Power.
TEST 6: Testing The Ignition Coil's Switching Signal
In this test step we're gonna' make sure that the igniter (ignition control module) is activating the ignition coil to spark. We'll do this by checking for the presence of the Switching signal on the black with white stripe wire (indicated by the arrow in the photo above).
The presence of the Switching Signal is verified using a regular 12 Volt test light and while your Honda Accord or Prelude is being cranked. In a nutshell, if the igniter is activating the ignition coil, when you crank your Honda's engine, the test light will flash on and off. Whatever the test light does with the Key On or Off does not matter, the results you need to worry about is when the engine is cranking.
IMPORTANT: If in TEST 3 you got spark from the ignition coil's high tension wire, you don't have to perform this test step. This test step checks for the Switching Signal which is responsible for making the ignition coil spark, so a spark result in TEST 3 confirms that the Switching Signal exists.
These are the test steps:
- Connect the alligator clip of the test light to the battery positive (+) terminal.
- With the probe end of the test light, probe the BLACK with WHITE stripe wire of the ignition coil's 3-wire connector. Here's some info to help you identify this circuit (wire):
- The connector MUST stay connected to the ignition coil for this test to work.
- Re-connect the ignition coil's high tension wire back onto the distributor, if you haven't done so already.
- Have your assistant crank the Accord (or Prelude) while you observe the test light.
- If the Switching signal is present, the test light will light on and off continuously as long as your assistant is cranking the engine.
That wasn't too hard.. lets interpret the results of this test to see what the next step is:
CASE 1: If the test light flashed ON and OFF while the engine was cranking, then the ignition coil is bad, replace it.
Here's why: The flashing on and off of the test light confirms that the Honda's igniter (ignition control module) is receiving its Triggering signal from the ECM (Electronic Control Module=Fuel Injection Computer) and that it's generating the Switching Signal... simply put: it's working correctly. So then, if the ignition coil is receiving 12 Volts (which you have already confirmed in TEST 4) and is receiving the switching signal from the igniter- IT HAS TO SPARK. Since it did not, it's bad.
CASE 2: If the test light DID NOT Flash ON and OFF while the engine was cranking, then go to: TEST 7 to test the igniter itself.
Here's why: The igniter (ignition control module) is the one that creates and provides the Switching Signal to the ignition coil. It could be bad or maybe it's not receiving the Triggering Signal it needs to generate the Switching Signal, therefore, we need TEST 7 to further investigate this.