How To Test The Igniter (1993-1994 1.8L Toyota Corolla)

TEST 3: Testing The Igniter Control Signal

At this point, your igniter diagnostic tests have confirmed a few things:

• The ignition coil isn't firing any spark.
• The BLK/ORG wire is delivering 10 to 12 Volts (TEST 1).
• The igniter's got a solid Ground connection (TEST 2).

Now, it's time to check if the fuel injection computer is actually sending the IGT activation signal to the igniter.

Like I said before, when you crank the engine, the computer generates the IGT signal based on data from the distributor's pickup coil.

That IGT signal is what tells the igniter exactly when to fire the ignition coil.

For this test, we're gonna use an LED test light to see if the IGT signal appears while cranking the engine.

IMPORTANT: Do NOT use a 12 Volt test light instead of an LED test light, or you might fry the igniter. If you need to buy an LED light, you can buy it here: Oznium Flush Mount 12V LED Light (at: amazon.com).

IMPORTANT: For this test to work, the distributor's gotta stay connected to both of its electrical connectors. To tap into the IGT signal inside the wire, you'll need to use either a back probe on the connector or a wire-piercing probe. Check out an example of a wire-piercing probe here: Wire Piercing Probe Review (Power Probe PWPPPPP01) (at: easyautodiagnostics.com).

Here are the test steps:

1. 1

   Connect the red LED wire to the black (BLK) wire that connects to terminal 1 on the distributor's 6-wire connector.
   
   If you're using a wire-piercing probe, make sure to pierce the wire as far from the connector as possible.
   
   NOTE: Keep both the 2-wire and 6-wire distributor connectors plugged into their engine wiring harness connectors.

2. 2

   Attach the black LED wire to the battery's negative (-) terminal.

3. 3

   Once the LED light is hooked up, have a helper crank the engine while you keep an eye on the LED light.

4. 4

   If the IGT signal is being sent to the igniter, the LED light should blink ON and OFF in steady pulses as the engine turns over.

Here's what your results mean:

CASE 1: The LED light blinked ON and OFF. That's exactly what you wanna see —it confirms the igniter's getting its activation signal from the fuel injection computer.

Now, let's see if the igniter's sending an activation signal to the ignition coil. Head over to: TEST 4: Testing The Ignition Coil Activation Signal.

CASE 2: The LED light DID NOT blink ON and OFF. That means the igniter isn't getting its IGT activation signal from the fuel injection computer.

If there's no IGT signal, the igniter won't trigger the ignition coil, so no spark's gonna reach the spark plug wires.

Most of the time, a missing IGT signal is caused by a faulty distributor pickup coil. Your next move? Test the distributor's pickup coil:

• How To Test The Distributor Pickup Coil (1993-1994 1.8L Toyota Corolla).

TEST 4: Testing The Ignition Coil Activation Signal

So far, your tests have confirmed:

• The ignition coil isn't firing any spark.
• The igniter's getting 10 to 12 Volts (TEST 1).
• The igniter's got a solid Ground connection (TEST 2).
• The igniter's receiving the IGT activation signal (TEST 3).

Now, there's just one last thing to check —whether the igniter's actually triggering the ignition coil.

To check for this triggering signal, we're gonna use a 12-volt test light. If you don't have one, here's the one I recommend:

• Lisle 28400 Heavy Duty 12 Volt Test Light (at: amazon.com).

IMPORTANT: All distributor connectors need to stay plugged in for this test to work.

Alright, let's dive in:

1. 1

   Clip the 12V test light's alligator clip onto the battery's positive (+) terminal.

2. 2

   Press the test light's metal probe against the ignition coil's (-) terminal (see image above).
   
   NOTE: Keep the probe touching the terminal while performing the next step.

3. 3

   Have a helper crank the engine while you watch the 12V test light.

4. 4

   If the ignition coil's being activated, the 12V test light should blink ON and OFF repeatedly while the engine cranks.

Here's what your results mean:

CASE 1: The 12V test light blinked ON and OFF. That's exactly what you wanna see.

This confirms the igniter is generating and sending the activation signal to the ignition coil, which means the igniter (ignition control module) is working just fine.

If you've already checked the following, then the ignition coil is faulty and needs to be replaced:

• No spark is coming from the ignition coil.
• The igniter's getting battery power and has a solid Ground connection (TEST 1 and TEST 2).
• The IGT activation signal is reaching the igniter (TEST 3).
• The igniter is successfully activating the ignition coil (this test section).

CASE 2: The 12V test light DID NOT blink ON and OFF. Without this activation signal, the ignition coil isn't gonna spark.

The igniter is bad and needs to be replaced, but only if you've already confirmed:

• The ignition coil isn't producing spark.
• The igniter's getting battery power and has a good Ground connection (TEST 1 and TEST 2).
• The igniter's receiving the IGT activation signal (TEST 3).
• The igniter IS NOT activating the ignition coil (this test section).

More 1.8L Toyota Corolla Tutorials

You can find a complete list of 1.8L Toyota Corolla tutorials and wiring diagrams in this index:

• 1.8L Toyota Corolla Index of Articles.

Here's a sample of the tutorials you'll find there:

• How To Test The Fuel Pump (1993-1997 1.8L Toyota Corolla).
• How To Test The MAP Sensor (1993-1997 1.8L Toyota Corolla).
• How To Test The Intake Air Temp (IAT) Sensor (1993-1997 1.8L Toyota Corolla).
• How To Test For A Blown Head Gasket (1993-2008 1.8L Toyota Corolla).