How To Test Ignition Coils (1995-1998 1.5L Toyota Tercel)

As you're already aware, two ignition coils supply spark to your 1.5L Toyota Tercel's cylinders.

In this tutorial, I'll explain how to test them. You'll quickly and easily determine if an ignition coil is causing a misfire or a no-start problem with your test results.

APPLIES TO: This tutorial applies to the following vehicles:

• 1995, 1996, 1997, 1998 1.5L Toyota Tercel

WIRING DIAGRAM: The following wiring diagrams have the ignition coil circuits:

• Igniter Wiring Diagram 1995-1996 1.5L Toyota Tercel.
• Ignition System Wiring Diagram (1997-1998 1.5L Toyota Tercel).

Symptoms Of A Bad Ignition Coil

An ignition coil that has failed will cause one of two problems:

• A misfire problem.
• An engine no-start problem.

If the ignition coil is causing a misfire problem, you're gonna' see one of the following trouble codes:

• P0300: Random Cylinder Misfire.
• P0301: Cylinder #1 Misfire.
• P0302: Cylinder #2 Misfire.
• P0303: Cylinder #3 Misfire.
• P0304: Cylinder #4 Misfire.

You'll also see one or more of the following symptoms:

• Lack of power when accelerating the engine under load.
• Bad gas mileage.
• Rough idle.

Ignition System Basics

The 1995-1998 1.5L Toyota Tercel uses a 'wasted spark ignition' system which uses one ignition coil for every two cylinders.

Specifically, the ignition coil provides spark for one of the paired cylinders on the compression stroke and the other on the exhaust stroke.

The paired cylinders that get spark simultaneously are:

• Cylinders 1 and 4.
  • Cylinder 1 gets spark delivered via a spark plug wire.
  • Cylinder 4 gets spark delivered via a spark plug boot.
• Cylinders 2 and 3.
  • Cylinder 2 gets spark delivered via a spark plug wire.
  • Cylinder 3 gets spark delivered via a spark plug boot.

Besides the two ignition coils, your Tercel's ignition system will have:

• An ignition control module (known as the igniter in Toyota speak).
• A crankshaft position (CKP) sensor.
• A camshaft position (CMP) sensor.

What Tools Do I Need To Test The Ignition Coils?

To test the ignition coils on your Toyota Tercel, you're going to need a few basic diagnostic tools. Here's the list:

• A multimeter.
• A spark tester.
  • The spark tester that I recommend (and that I use) is the HEI spark tester. This is an accurate and inexpensive spark tester and you can buy it here: OTC 6589 Electronic Ignition Spark Tester (at: amazon.com).
• An LED light.
  • The LED light is used to test for the ignition coil activation signals in TEST 4 and TEST 5.
  • You can find out more about it and where to buy it here: The LED Light Test Tool And How To Make One (at: easyautodiagnostics.com).
• Basic hand tools.
  • You'll need some basic hand tools to remove the bolt holding the ignition coil down on the valve cover.

Where To Buy The Ignition Coils And Save

The following ignition coils are manufactured by known-automotive parts suppliers (no knock-offs) and will fit the 1995-1998 1.5L Toyota Tercel:

TEST 1: Checking For Spark With A Spark Tester

The first step in diagnosing the ignition system on your 1.5L Toyota Tercel is to see if all four cylinders are getting spark.

It's important to remember that:

• Cylinders 1 and 4 receive spark from the 1/4 ignition coil sitting on top of cylinder 4.
• Cylinders 2 and 3 receive spark from the 2/3 ignition coil sitting on top of cylinder 3.

NOTE: To get the most accurate test result, you need to use a dedicated spark tester. If you don't have one, I recommend the HEI Spark Tester, and you buy it here: OTC 6589 Electronic Ignition Spark Tester.

Let's get testing:

PART 1:

1. 1

   Disconnect the #1 cylinder spark plug wire and connect it to the spark tester (see photo 1 of 2 above).

2. 2

   Ground the HEI spark tester with a battery jump start cable directly on the battery negative (-) terminal.

3. 3

   Have a helper crank the engine while you observe the spark tester.
   
   Once done, remove the spark tester and reconnect the spark plug wire to its spark plug.

4. 4

   The spark tester should spark.

5. 5

   Repeat steps 1 thru 5 on the #2 cylinder spark plug wire.

PART 2:

1. 6

   Remove the ignition coil sitting on top of the #3 cylinder spark plug.

2. 7

   Connect your spark tester to the ignition coil's spark plug boot (see photo 2 of 2 above).
   
   NOTE: The ignition coil must remain connected to its spark plug wire.

3. 8

   Ground the HEI spark tester with a battery jump start cable directly on the battery negative (-) terminal.

4. 9

   Have a helper crank the engine while you observe the spark tester.
   
   Once done, remove the spark tester, install the ignition coil, and bolt it down.

5. 10

    The spark tester should spark.

6. 11

   Repeat steps 6 thru 10 on the ignition coil sitting on top of the #4 cylinder spark plug.

Let's see what your test results mean:

CASE 1: All ignition coils sparked. This is the correct and expected test result and tells you that the ignition coils are OK.

With this test result you can also conclude that:

• The igniter (ignition control module) is good.
• The crankshaft position (CKP) sensor is good.

CASE 2: All ignition coils DID NOT spark. This usually tells you that the ignition control module (igniter) or the crankshaft position sensor is bad.

Your next step is to see if both ignition coils are receiving an activation signal. Go to: TEST 5: Checking The Ignition Coils' Activation Signals.

CASE 3: Cylinder #1 IS NOT receiving spark (but the other 3 are). This test result usually means that either the spark plug wire or the ignition coil is defective.

The next step is to check for spark directly on the ignition coil's tower. Go to: TEST 2: Checking For Spark Directly On The Ignition Coil's Tower.

CASE 4: Cylinder #2 IS NOT receiving spark (but the other 3 are). This test result usually means that either the spark plug wire or the ignition coil is defective.

The next step is to check for spark directly on the ignition coil's tower. Go to: TEST 2: Checking For Spark Directly On The Ignition Coil's Tower.

CASE 5: Cylinder #3 IS NOT receiving spark (but the other 3 are). This test result confirms that the ignition coil sitting on top of cylinder #3 is bad if all the other cylinders are getting spark.

Replace the ignition coil only if you have confirmed that all other cylinders are getting spark.

CASE 6: Cylinder #4 IS NOT receiving spark (but the other 3 are). This test result confirms that the ignition coil sitting on top of cylinder #4 is bad if all the other cylinders are getting spark.

Replace the ignition coil only if you have confirmed that all other cylinders are getting spark.

CASE 7: Cylinders #1 and #4 ARE NOT receiving spark. This test result usually tells you that the ignition coil sitting on top of cylinder #4 is bad if cylinders #2 and #3 are getting spark.

So that you can be sure that the ignition coil is bad, your next step is to ensure that it's receiving power. Go to: TEST 3: Making Sure The Ignition Coil Is Getting Power.

CASE 8: Cylinders #2 and #3 ARE NOT receiving spark. This test result usually tells you that the ignition coil sitting on top of cylinder #3 is bad if cylinders #1 and #4 are getting spark.

So that you can be sure that the ignition coil is bad, your next step is to ensure that it's receiving power. Go to: TEST 3: Making Sure The Ignition Coil Is Getting Power.