Coil Pack Circuit Descriptions

1999-2001 Coil Pack Diagnostic Tests (Chrysler 3.3L) 1999-2001 Coil Pack Diagnostic Tests (Chrysler 3.3L)

It's important to know what the 4 wires coming out of the Chrysler coil pack connector do and below you'll learn the Circuit Descriptions of each.

  1. Circuit labeled 1:
    1. Switching Signal Circuit for Spark Plugs 3 and 6.
  2. Circuit labeled 2:
    1. Switching Signal Circuit for Spark Plugs 1 and 4.
  3. Circuit labeled 3:
    1. Power (12 Volts) Circuit
  4. Circuit labeled 4:
    1. Switching Signal Circuit for Spark Plugs 2 and 5.

You've probably noticed that there's no mention of the color of the wires of the three wires coming out of the connector, well the color is not important (to take advantage of the info in this article) as long as you're able to correctly identify the circuit by its number in the photos supplied.

Basic Operating Theory

1999-2001 Coil Pack Diagnostic Tests (Chrysler 3.3L)

The PCM (Powertrain Control Module= Fuel Injection Computer) is the one that controls the whole show in this type of ignition system since the ‘Ignition Control Module' function is handled by the PCM itself. So, in a nutshell, here's what happens when you turn the key to crank and start the car:

  1. The Crankshaft Position Sensor starts to create its Crank Signal, as the engine cranks.
  2. The Crank Signal, upon being received by the PCM along with other necessary sensor information, starts to do its little song and dance and activates the Auto Shut Down (ASD) Relay and decides which ignition coil (within the coil pack assembly) to fire. It does this by sending the coil pack three different Switching Signals (thru' separate circuits)
    1. The term Switching signal describes the PCM's action of switching the Primary Current (12 Volts), flowing thru' each ignition coil within the coil pack, on and off by interrupting their ground path. It's this signal that makes the ignition coils fire spark.
    2. The ASD Relay is the one that powers the coil pack and this only happens with the engine cranking or running. The ASD Relay will not power up the coil pack with just the Key in the On Position (and Engine Off).
  3. The coil pack is made up of three separate and individual ignition coils, therefore each one gets its own switching signal from the PCM. Each ignition coil within the coil pack has two towers that feed spark to two cylinders at the same time.
    1. One ignition coil within the coil pack fires spark to cylinders 3 and 6.
    2. One ignition coil fires cylinders 1 and 4.
    3. The other ignition coil fires cylinders 2 and 5.
  4. As each individual ignition coil, within the ignition coil pack, get their Switching Signal, they then fire spark to two different cylinders at the exact same time (in what's known as the Waste Spark method).

To test the Chrysler ignition coil (for these specific 3.3L Chrysler engines this article covers) the only thing that you have to worry about is knowing that two cylinders get spark at the exact same time (#3 and #6, #1 and #4, #2 and #5) from seperate ignition coils within the coil pack assembly.

Precautions, Do's And Don'ts

The tests you're about to learn are pretty simple and easy but, since most of them are done with the engine cranking, you need to be alert and on your toes. Take all necessary safety precautions to keep your fingers, hands and entire self safe. Here are a few other tips and suggestions:

  1. All of the coil pack tests in this article are ON CAR TESTS. Do not remove the ignition coil pack from the vehicle.
  2. Do not use a regular spark plug instead of a spark tester to test for spark.
  3. Do not remove the spark plug wire from the spark plug or the ignition coil while the engine is cranking to test for spark.
  4. It's important that you start your Diagnostic from TEST 1, do not skip around from test to test unless specifically instructed to do so by the TEST you are currently on.
  5. Do not use a 12 Volt test light where an LED light is called for.
  6. Once again, use the recommended/indicated tools for all of your tests.