This article will help you to troubleshoot and diagnose a 'no-spark no-start', or a misfire condition on your Chrysler, Dodge, or Plymouth 3.0L V6 equipped car or mini-van. You DO NOT need a scan tool to take advantage of the step by step diagnostic instructions in this article.
You'll be able to pinpoint the problem to the ignition coil or the crankshaft position sensor (located within the distributor) or the spark plug wires or the distributor cap.
Since this article covers quite a few Chrysler makes and models, you can take a look at the application chart at the bottom of this page to see if this article applies to your specific vehicle.
You can find this tutorial in Spanish here: Cómo Probar El Sistema De Encendido (3.0L Chrysler, Dodge, Plymouth) (at: autotecnico-online.com).
How Does This Type Of Ignition System Work?
Here's a little background information that will help you diagnose the ignition system on your Chrysler vehicle. In a nutshell, when the system is working properly and you turn the key to crank and start your Chrysler (or Dodge or Plymouth) car or mini-van:
- The distributor shaft starts to rotate which causes the crankshaft position sensor to start generating a crankshaft and camshaft position signal, which are sent directly to the fuel injection computer (Henceforth known as the PCM).
- With these two signals, the PCM activates the Auto Shutdown (ASD) Relay to feed power to pretty much every electronic component under the hood, especially the ignition coil.
- Without these two signals, the PCM will not activate the ASD Relay.
- Also, with the signals from the crankshaft (and camshaft) position sensor assembly, the PCM starts to activate the ignition coil to start sparking away. It does this by switching the primary current, flowing across the ignition coil, ON and OFF. This ON/OFF action will henceforth be called the Switching signal.
The crank sensor is at the heart of this type ignition system. here are some useful facts that you should be aware of about the crank sensor on your Chrysler (or Dodge or Plymouth) vehicle:
- The crankshaft position sensor assembly is located in the distributor.
- It's an optical type sensor.
- It produces a crankshaft position signal and a camshaft position signal.
- Both signals produce a digital square wave, if tested on an oscilloscope.
- Both of these signals can also be tested with an inexpensive LED light (which is the method I'll use in this article).
- If it goes bad, the your Chrysler car or mini-van will crank but not start.
What Tools Do I Need?
No expensive tools are required to test this type of ignition system. Now, having said that, there some very specific tools that I recommend to use for the tests. So, here's the basic list:
- A Spark tester
- Not just any type of spark tester. I strongly suggest you buy the HEI spark tester (don't have an HEI Spark Tester? Need to buy one? You can buy it here: OTC 6589 Electronic Ignition Spark Tester).
- Don't use a regular spark plug instead of a dedicated spark tester.
- Don't pull the spark plug wire off of the spark plug as the engine is cranking or running. This will give a false result and/or damage the ignition coil.
- An LED light.
- Click here to see what this looks like: The LED Light Test Tool And How To Make One
- Test light.
- Multimeter.
- A cheapie one will do (don't have a digital multimeter? Need to buy one? Click here to see my recommendations: Buying A Digital Multimeter For Automotive Diagnostic Testing).
- Repair manual.
- For whatever other information this article does not cover.
- Helper.
- To help you crank the engine while you observe the LED light (or test light or multimeter).
By the way, you don't need an automotive scan tool for any of these tests.
Crank Sensor: Circuit Descriptions
The crankshaft position sensor is a four-wire sensor and it is made up of two sensors in one assembly. It's located inside the distributor. Below are the circuit descriptions that I'll be using across this article.
- Circuit 1
- Ground Circuit. Provided by the fuel injection computer internally. This is a black with light blue stripe (BLK/LT BLU) wire.
- Circuit 2
- Power Circuit. 8 Volts that are provided by the fuel injection computer. Orange (ORG) wire.
- Circuit 3
- Camshaft Position Signal. Tan with yellow stripe (TAN/YEL) wire.
- Circuit 4
- Crankshaft Position Signal. Gray with black stripe (GRY/BLK) wire.
IMPORTANT: It will be necessary to test some of these circuits while the engine is being cranked. Be careful, use common sense and take all necessary safety precautions.
Ignition Coil: Circuit Descriptions
The ignition coil has just two wires coming out of its connector. One feeds it with power (10 to 12 Volts) and the other feeds it the Switching signal. Below are the circuit descriptions that I'll be using in this article.
- Circuit 1
- Switching Signal Circuit. Black with gray stripe (BLK/GRY) wire.
- Circuit 2
- Power Circuit (10 to 12 Volts). Power supplied only when cranking the engine and with engine running. Dark green with orange stripe (DK GRN/ORG) wire.
IMPORTANT: It will be necessary to test some of these circuits while the engine is being cranked. Be careful, use common sense and take all necessary safety precautions.
