Crank (CKP) Sensor Working Theory

How To Test The Crank Sensor -No Spark No Start Tests (Chrysler 3.0L, 3.3L, 3.8L)

The crankshaft position sensor, on your 3.0L, 3.3L, 3.8L Chrysler equipped car or mini-van, is a Hall-Effect three wire crankshaft position sensor. What this means: it produces an On/Off DC voltage signal that can be easily measured with a multimeter, an Oscilloscope, and even an LED Light.

Each one of the three wires that connect to it have a specific job to do. One delivers power in the form of 5 or 8 Volts from the PCM. Another delivers ground. This ground is provided inside the PCM, too. The last remaining, delivers the signal, that the CKP sensor creates, to the PCM.

Here's the wire-by-wire breakdown:

  1. The wire labeled with the number 3 delivers power in the form of 5 or 8 Volts from the PCM.
  2. The wire labeled with the number 2 delivers ground. This ground is provided inside the PCM, too.
  3. The wire labeled with the number 1 delivers the signal, that the crank sensor creates, to the PCM.

The most important thing to know, is that if the CKP goes BAD, your Chrysler (or Dodge or Plymouth) vehicle will crank but not start.

Here are a few other specific symptoms you'll see when the crank sensor goes bad:

  1. No spark from any of the COP ignition coils.
  2. No fuel injector pulses (as tested with a fuel injector noid light).
  3. ASD relay doesn't stay activated beyond the initial 5 to 10 seconds the engine is being cranked by the starter motor.

Related Test Articles

You'll find all of the 3.0L, 3.3L, 3.8L Chrysler How to test articles here: Chrysler 2.7L, 3.3L, 3.5L, 3.8L Index of Articles.