How To Test The Coil Packs, Ignition Module And CKP Sensor (1989-1994 2.3L Ranger, Mustang, B2300)

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As mentioned at the beginning of the article, there are two types of ignition system problems this tutorial will cover, and to get you started at the right place, choose one of the following:

1. Engine does not start due to a no-spark condition.
   • This usually means one of two things: either you have a bad CKP sensor on your hands, or a bad ignition control module (ICM).
   • Your starting point is: TEST 1: Testing For Spark (Engine Does Not Start).
2. Engine starts but runs with a misfire (engine miss).
   • This is caused by one or more spark plug wires not sparking.
   • Your starting point is: TEST 2: Testing For Spark (Engine Starts).

TEST 1: Testing For Spark (Engine Does Not Start)

IMPORTANT: This test section only applies if the engine does not start. If the engine starts but runs rough or with a misfire, go to TEST 2.

We're going to check the four exhaust manifold side spark plug wires for spark. To obtain an accurate test result, the spark test must be done with a spark tester.

If you don't have one, I recommend the HEI spark tester and you can buy it here: HEI Spark Tester.

To correctly interpret your test result, the following is important to keep in mind:

• Cylinders #1 and #4 are paired cylinders and their exhaust side spark plugs receive spark simultaneously.
• Cylinders #2 and #3 are paired cylinders and their exhaust side spark plugs receive spark simultaneously.

OK, let's get started:

1. 1

   Disconnect the cylinder number 1 exhaust side spark plug wire from its spark plug.

2. 2

   Connect your spark tester to the spark plug wire.

3. 3

   Have your helper crank the engine.

4. 4

   The spark tester should spark.

5. 5

   Repeat steps 1 trough 4 on the remaining 3 exhaust side spark plugs.

Let's interpret your test result:

CASE 1: None of the spark plug wires sparked. A no-spark result in all four spark plug wires usually indicates a bad CKP sensor or a defective ignition control module.

Thankfully, we can find out. Your next step is to make sure that the ignition coil and ignition control module are getting 10 to 12 Volts. Go to: TEST 3: Making Sure The ICM Is Getting 12 Volts.

CASE 2: All four park plug wires sparked. This tells you that the ignition system is not behind the engine no-start problem.

CASE 3: Spark plug wires for cylinder #1 and #4 DID NOT spark. This usually means that the ignition coil pack is bad.

To make sure the ignition coil pack is bad, your next step is to make sure that it is getting the 1/4 ignition coil activation signal. Go to: TEST 5: Checking For Spark Directly On The 1/4 Ignition Coil Towers (Exhaust Side).

CASE 4: Spark plug wires for cylinder #2 and #3 DID NOT spark. This usually means that the ignition coil pack is bad.

To make sure the ignition coil pack is bad, your next step is to make sure that it is getting the 2/3 ignition coil activation signal. Go to: TEST 6: Checking For Spark Directly On The 2/3 Ignition Coil Towers (Exhaust Side).

TEST 2: Testing For Spark (Engine Starts)

IMPORTANT: This test section only applies if the engine starts. If the engine DOES NOT start, your starting point is TEST 1.

We're going to check all eight spark plug wires for spark. To obtain an accurate test result, the spark test must be done with a spark tester.

If you don't have one, I recommend the HEI spark tester and you can buy it here: HEI Spark Tester.

To correctly interpret your test result, the following is important to keep in mind:

Exhaust manifold side:

• Cylinders #1 and #4 are paired cylinders and their exhaust side spark plugs receive spark simultaneously.
• Cylinders #2 and #3 are paired cylinders and their exhaust side spark plugs receive spark simultaneously.

Intake manifold side:

• Cylinders #1 and #4 are paired cylinders and their intake side spark plugs receive spark simultaneously.
• Cylinders #2 and #3 are paired cylinders and their intake side spark plugs receive spark simultaneously.

OK, let's get started:

PART 1: Exhaust Side Spark Plug Wires

1. 1

   Disconnect the cylinder number 1 exhaust side spark plug wire from its spark plug.

2. 2

   Connect your spark tester to the spark plug wire.

3. 3

   Have your helper crank the engine.

4. 4

   The spark tester should spark.

5. 5

   Repeat steps 1 trough 4 in the remaining 3 exhaust side spark plugs.

PART 2: Intake Side Spark Plug Wires

1. 6

   Disconnect the cylinder number 1 intake side spark plug wire from its spark plug.

2. 7

   Connect your spark tester to the spark plug wire.

3. 8

   Have your helper crank and start the engine.
   
   NOTE: The intake manifold side spark plug wires will only spark after the engine has started.

4. 9

   The spark tester should spark.

5. 10

   Repeat steps 6 trough 9 in the remaining 3 intake side spark plugs.

Let's interpret your test result:

CASE 1: Spark plug wires for cylinder #1 and #4 DID NOT spark (EXHAUST SIDE). This could be caused by a defective ignition coil pack.

To make sure the ignition coil pack is bad, your next step is to check for spark directly on the ignition coil towers that feed spark to the exhaust side spark plugs for cylinders 1 and 4. Go to: TEST 5: Checking For Spark Directly On The 1/4 Ignition Coil Towers (Exhaust Side).

CASE 2: Spark plug wires for cylinder #2 and #3 DID NOT spark (EXHAUST SIDE). This could be caused by a defective ignition coil pack.

To make sure the ignition coil pack is bad, your next step is to check for spark directly on the ignition coil towers that feed spark to the exhaust side spark plugs for cylinders 2 and 3. Go to: TEST 6: Checking For Spark Directly On The 2/3 Ignition Coil Towers (Exhaust Side).

CASE 3: Spark plug wires for cylinder #1 and #4 DID NOT spark (INTAKE SIDE). This could be caused by a defective ignition coil pack.

To make sure the ignition coil pack is bad, your next step is to check for spark directly on the ignition coil towers that feed spark to the intake side spark plugs for cylinders 1 and 4. Go to: TEST 7: Checking For Spark Directly On The 1/4 Ignition Coil Towers (Intake Side).

CASE 4: Spark plug wires for cylinder #2 and #3 DID NOT spark (INTAKE SIDE). This could be caused by a defective ignition coil pack.

To make sure the ignition coil pack is bad, your next step is to check for spark directly on the ignition coil towers that feed spark to the intake side spark plugs for cylinders 2 and 3. Go to: TEST 8: Checking For Spark Directly On The 2/3 Ignition Coil Towers (Intake Side).

CASE 5: One spark plug wire did not spark (all of the other 7 did). This could be caused by a defective ignition coil pack or a bad spark plug wire.

Your next step is to go to: TEST 15: Checking For Spark Directly On The Ignition Coil Tower.

CASE 6: Two spark plug wires that DO NOT belong to 'paired' cylinders DID NOT spark. This could be caused by a defective ignition coil pack or bad spark plug wires.

Your next step is to go to: TEST 15: Checking For Spark Directly On The Ignition Coil Tower.

TEST 3: Making Sure The ICM Is Getting 12 Volts

In this test section, we'll check that the ignition control module (ICM), the crankshaft position sensor, and the ignition coil packs are receiving 10 to 12 Volts.

The same circuit that supplies ignition voltage to the ICM also supplies the ignition coil packs and the CKP sensor.

I recommend using a multimeter to test for ignition voltage for a more accurate test result.

OK, this is what you need to do:

PART 1:

1. 1

   Set your multimeter to Volts DC mode.

2. 2

   Disconnect the top ICM connector.
   
   NOTE: The top connector is the black connector.

3. 3

   Connect the red multimeter lead to the wire labeled with the number 1 of the top ICM connector using the appropriate tool.
   
   NOTE: It is not possible to probe the front of the connector or you risk damaging the female terminal inside.

4. 4

   Ground the black multimeter test lead directly to the negative (-) battery post.

5. 5

   Turn the key to the ON position.

6. 6

   Your multimeter should register 10 to 12 Volts DC.

PART 2:

1. 7

   Disconnect the ignition coil packs from their electrical connectors.

2. 8

   Connect the red multimeter test lead to the RED/GRN wire of exhaust side ignition coil pack connector.
   
   The RED/GRN wire connects to the terminal labeled with the number 2 in the illustration of the coil pack connector above (image 2 of 2).

3. 9

   Ground the black multimeter test lead directly to the negative (-) battery post.

4. 10

   Turn the key to the ON position.

5. 11

   Your multimeter should register 10 to 12 Volts DC.

6. 12

   Repeat steps 8 through 11 on the intake side ignition coil pack connector.

OK, let's interpret your test results:

CASE 1: Your multimeter showed 10 to 12 Volts at the indicated testing points. This tells you that the ignition control module (ICM), the CKP sensor, and the ignition coil packs are getting power.

The next step is to check that the ICM and CKP sensor are getting Ground. Go to: TEST 4: Making Sure The ICM And CKP Sensor Are Getting Ground.

CASE 2: Your multimeter DID NOT show 10 to 12 Volts. Recheck all of your multimeter connections and repeat the test one more time.

If after double checking and repeating the test you still do not have 10 to 12 Volts at the indicated testing point, your next step is to find out the reason for this missing voltage.

Without 10 to 12 Volts, the ignition control module, crankshaft position sensor and both ignition coil packs will not function.

Restoring 12 Volts to this circuit should solve your no-spark no-start condition on your 2.3L Ford Ranger (Ford Mustang, Mazda B2300).