Coil Pack Circuit Descriptions
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.
- Circuit labeled 1:
- Switching Signal Circuit for Spark Plugs 3 and 6.
- Circuit labeled 2:
- Switching Signal Circuit for Spark Plugs 1 and 4.
- Circuit labeled 3:
- Power (12 Volts) Circuit
- Circuit labeled 4:
- 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.
How The Coil Pack Works
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:
The Auto Shut Down (ASD) Relay provides the ignition coil pack with 12 Volts (only when the engine is cranking or running).
The Crankshaft Position Sensor starts to create its Crank Signal, as the engine cranks.
The Crank Signal, upon being received by the PCM along with other necessary sensor information, starts to do its little song and dance 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).
- 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.
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. These two cylinders (that get spark at the same time) are called ‘Paired Cylinders’
- One ignition coil within the coil pack fires spark to cylinders 3 and 6. So, cylinders 3 and 6 are ‘Paired Cylinders’.
- One ignition coil fires cylinders 1 and 4. So, cylinders 1 and 4 are ‘Paired Cylinders'.
- the other ignition coil fires cylinders 2 and 5. So, cylinders 2 and 5 are ‘Paired Cylinders’.
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, 3.8L 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 separate ignition coils within the coil pack assembly.