How To Test a Ford Mustang Ignition Coil

How To Test a Ford Mustang Ignition Coil


The Mustang Ignition Coil in your 3.8 liter V6 Ford is a high voltage ignition system that drives the spark to your engine. When you have a Ford Mustang misfire condition or problems with your spark, this How To DIY tutorial can show you how to test your Mustang Ignition Coil.

There’s not much to this coil as your 3.8 liter V6 Ford engine is a DIS (Distributorless Ignition System). To complete this How To tutorial you will need a digital multimeter to test the voltage and signals. Today ‘ll be showing you how to test your Mustang Ignition Coil in a 2000 Ford V6.

How To Test a Ford Mustang Ignition Coil 1

Our 2000 Ford Mustang test vehicle is equipped with an automatic transmission, which is shifting very harshly. That’s just one of the symptoms that’s common in Ford Mustang ignition coil failure.

Symptoms of a bad Mustang Ignition Coil

If your V6 Mustang coil has gone bad, there’s a few symptoms that can arise from the failed part. Here’s a few other symptoms that can come up from having your failed ignition coil.

  • Ford Mustang won’t start
  • Engine Misfire
  • Poor idle
  • Spark plugs keep fouling
  • Harsh shifting
  • Mustang takes a long time to start ( hard starting )
  • OBDII Check Engine Light ON for misfire – P0300, P0301, P0302, P0303, P0304, P0305, P0306

To begin our Mustang Ignition Coil test, you will be checking the coilpack for a switched power signal. In order to do this, you will need to insert your Ford ignition key and turn to the “ON” position. Yo do not need to start your engine, but simply turn to the “ON” position.

Test your Mustang Ignition Coil for Power

While you can perform this part of the test by disconnecting your ignition coil, it’s better to simply pierce the wire in question instead. With your key turned to the “ON” position, probe the back of PIN D as shown in our Mustang Ignition Coil wiring diagram below.

Ford Mustang Ignition Coil 1

PIN D is a RED wire and it should return a 12 volt signal with your key turned to the “ON” position. If you have power at this wire but your Mustang still has NO SPARK, this can be caused from a variety of issues.

The next part of our test is the switching signal from your Powertrain Control Module (PCM) to your Mustang ignition coil. If you don’t have power at this wire, make sure the key is turned to the “ON” position. Still no power at that pin? Check the fuse for your ignition coil in your fuse panel.

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How the Ford Mustang ignition coil works

When you turn your ignition key to the “START” position, your ignition coil receives 12 volts of power at PIN D. As the starter turns your 3.8 liter V6 engine, the PCM receives the signal from your crankshaft position sensor. Your Ford Mustang engine computer then sends a switching signal to the ignition coil that will signal the coil to fire off spark to your spark plugs.

Ford Mustang 3.8 liter Firing Order

If your Mustang check engine light is already on, and you have a misfire code that’s specific ( meaning not generic misfire P0300) you know which spark plug to check.

Ford Mustang Ignition Coil 11


Test your Mustang Ignition Coil Switching Signal

If you know which cylinder is acting up in your Ford Mustang misfire condition, then this part is simple to do. Using the proper testing tool, you can check for the switching signal at PIN A, PIN B and PIN C.

  1. PIN A: Switching Signal for Cylinders 3 and 4.
  2. PIN B: Switching Signal for Cylinders 2 and 6.
  3. PIN C: Switching Signal for Cylinders 1 and 5.

When you are piercing the wires at these pins to check for signal, make sure that you are isolating your wire so you don’t mix or cross wires. Make sure that you keep clear of your Ford engine and drive belts, as well as the cooling fans when testing for switching signal.

Have a friend crank your engine over, to check for the switching signal at the ignition coil. If you have a specific cylinder that’s dead, but the corresponding cylinder isn’t firing, check your spark plug wire or spark plug. For example, if you have a check engine code for a Ford Mustang Cylinder Misfire in cylinder 1, but cylinder 5 works just fine the spark plug wire should be replaced next.

If you find that you have power at your Ford Mustang Ignition Coil but spark isn’t arriving at your spark plugs, it’s time to replace your ignition coil pack. Have any questions about our Mustang Ignition Coil tutorial? Leave us a message below and let us know!