TEST 6: Making Sure The Ignition Control Module Is Getting Ground
For the ignition control module to activate the ignition coil, it has to have a good path to Ground.
So in this test section we're gonna' make sure that the black with blue stripe (BLK/BLU) wire of the 7-wire distributor connector is providing this Ground.
In the photo above, the BLK/BLU wire connects to the female terminal I've labeled with the letter D.
To check for the presence of Ground in the BLK/BLU wire, we're gonna' do a simple multimeter voltage test on the wire.
These are the test steps:
Select Volts DC mode on your multimeter.
Disconnect the distributor from its 7-wire connector.
With the black multimeter test lead probe the female terminal labeled with the letter D.
The female terminal I've labeled with the letter D connects to the BLK/BLU wire.
Connect the red multimeter test lead to the battery (+) positive terminal.
Your multimeter should display 10 to 12 Volts DC.
This is a chassis Ground and is available at all times, so there's no need to turn the key to the ON position.
Let's analyze your test result:
CASE 1: Your multimeter displayed 10 to 12 Volts. This is the correct test result and lets you know that the ignition control module has a good path to Ground.
The next step is to check that the ignition control module is receiving an activation signal from the fuel injection computer. For this test go to: TEST 7: Testing The Ignition Control Module's Activation Signal.
CASE 2: Your multimeter DID NOT display 10 to 12 Volts. Without Ground the ignition control module will not activate the ignition coil.
Your next step is to resolve this Ground issue. Once Ground is restored, the ignition control module will activate the ignition coil.
TEST 7: Testing The Ignition Control Module's Activation Signal
For the ignition control module to activate the ignition coil, it has to receive the instructions do so from the fuel injection computer.
These instructions come by the way of an activation signal on the yellow with black stripe (YEL/BLK) wire of the distributor's 7-wire connector.
In this test, you're gonna' check to see if the ignition control module is being supplied with it when the engine is being cranked.
For this test you'll need to use a multimeter that can read Hertz frequency since an LED light will not work here since the signal's frequency is so fast that you can not see it with an LED light.
Don't have a digital multimeter that can read Hertz frequency? See my recommendations here: Buying A Digital Multimeter For Automotive Diagnostic Testing (at: easyautodiagnostics.com).
NOTE: It's important that the battery be in a fully charged condition for this test.
IMPORTANT: The distributor must remain connected to its 7-wire connector to be able to test the signal. You'll need to use a back probe on the connector or a wire piercing probe on the wire to access the signal.
OK, let's get started:
Reconnect the distributor to its 7-wire connector.
Select Hertz (Hz) frequency mode on your multimeter.
Connect the red multimeter test lead to the YEL/BLK wire.
The YEL/BLK wire connects to the female terminal I've labeled with the letter E.
Since the connector must remain connected to the distributor, you'll need to back probe the connector or use a wire piercing probe on the wire.
Connect the black multimeter test lead to the battery's negative (-) terminal.
Once everything is set up, have your helper crank the engine while you observe the multimeter.
Your multimeter will register around 3 to 8 Hertz (Hz) on its display screen if the ICM's activation signal is present.
Let's interpret your test result:
CASE 1: The multimeter registered the indicated Hertz (Hz) values. This is the correct test result.
You can conclude that the ignition control module is fried only if you have:
- Confirmed that there's no spark coming out of the ignition coil (TEST 3).
- Confirmed that the ignition coil is getting power (TEST 4).
- Confirmed that the ignition coil's activation signal is missing (TEST 5).
- Confirmed that the ignition control module is getting its activation signal.
Replacing the ignition control module will solve your no-spark/no-start problem. Now, at the time of this writing the only way to buy a ignition control module is to buy the whole distributor.
CASE 2: The multimeter DID NOT register the indicated Hertz (Hz) value. Without this activation signal the ignition control module will not activate the ignition coil.
Recheck all of your connections. If still the multimeter does not register the indicated Hertz values, this usually indicates that the camshaft position sensor (located inside the distributor) is defective.
Your next step is to test the camshaft position sensor:
Other Causes Of A Misfire
Quite a few other things can cause a misfire problem (besides an ignition system problem). If this is happening to you, here are a couple of suggestions that might help:
- The valve cover gaskets are leaking oil onto the spark plug wells and soaking the spark plugs and spark plug wire boots in oil.
- Over time, this oil will cause a misfire as the oil cooks and turns into carbon tracks.
- The photos in the image viewer show you what a carbon track looks like on the inside of the spark plug wire boot and on the ceramic insulator of the spark plug.
- One or more cylinders have low compression.
- One of the most overlooked diagnostic tests to find the root cause of misfire is the compression test.
- You'll need an engine compression tester of course.
- The engine compression readings between cylinders should not vary more 15%.
- How To Test Engine Compression (1995-1998 1.5L Mazda Protege).
- Carbon tracks on the spark plug(s) and in the inside of the spark plug wires.
- The photos in the image viewer point (the orange arrows) to what carbon tracks look like.
- Replace the components as affected with carbon tracks.
- Carbon Tracks Are A Common Cause Of Ignition Misfires (at: easyautodiagnostics.com).
- Broken spark plugs.
- This usually happens at tune-up time, if you have dropped one on the floor.
- You power washed the engine (this is something that should never be done on any vehicle).
- A bad or dirty/clogged fuel injector.
More 1.5L Mazda Protege Tutorials
You can find a complete list of 1.5L Mazda Protege tutorials in this index:
Here's a small sample of the tutorials you'll find in the index:
- P0122 -What Does It Mean? (1996-1998 1.5L Mazda Protege).
- How To Test The TPS (1996-1998 1.5L Mazda Protege).
- How To Test The MAF Sensor (1996-1998 1.5L Mazda Protege).
- How To Test Engine Compression (1995-1998 1.5L Mazda Protege).
If this info saved the day, buy me a beer!