Symptoms Of A Bad Ford Crankshaft Position Sensor

You're probably ready to get this test started and over with, but, before you do...

You need to keep one very important thing in mind: When the CKP sensor fails (goes bad), the most obvious symptoms is a Cranks but Does Not Start condition due to no spark and no fuel injection.

With a bad crankshaft position sensor on your Ford 4.6L or 5.4L vehicle you'll also see one of the following symptoms:

  1. If the vehicle is coil pack equipped: The ignition control module will not produce its PIP signal and thus, the PCM will not activate the fuel injectors.
    1. You can verify this by using a noid light to check for the fuel injector pulses.
    2. If the fuel injector pulses are present, the crankshaft position sensor is OK.
  2. If the vehicle is COP coil equipped: The PCM will not activate the fuel injectors.
    1. You can verify this by using a noid light to check for the fuel injector pulses.
    2. If the fuel injector pulses are present, the crankshaft position sensor is OK.
  3. No spark to any of the 8 engine cylinders.
    1. You can verify this by using a spark tester and checking each spark plug wire or COP coil.
    2. If spark is present (even if it's just at one cylinder), the crankshaft position sensor is OK.

OK, enough reading, let's get testing!

TEST 1: Verifying The Crankshaft Position Signal

Verifying The Crankshaft Position Signal. How To Test The Crankshaft Position Sensor (Ford 4.6L, 5.4L)

The crankshaft position sensor on the 4.6L and 5.4L Ford engines is a two wire sensor that can be easily tested with your multimeter in AC Volts.

Remember, the battery must be fully charged for this test to produce an accurate result. Why? Well, because the strength of crankshaft position sensor's signal, that you'll be measuring with your multimeter, depends on the amount of RPMs your engine is turning as it's cranking.

The following test steps assume that you 4.6L or 5.4L pick up (car, van, or SUV) Cranks But Does Not Start (if you haven't already read the section: Symptoms Of Bad Ford Crankshaft Position Sensor, please do so now). OK, this is what you need to do:

  1. 1

    Disconnect the crankshaft position sensor's electrical connector and remove some of the plastic wire loom protector and/or the black electrical tape that shields/protects the two wires of the crankshaft position (CKP) sensor.

  2. 2

    Reconnect the connector to the crankshaft position sensor now and place your multimeter in Volts AC mode.

  3. 3

    Using a wire-piercing probe or another appropriate tool, probe the number 1 and number 2 wires of the crankshaft position sensor with the multimeter test leads.

    To see what a what wire piercing probe tool looks like, click here: Wire Piercing Probe.

    It doesn't matter which multimeter test lead (RED or BLACK) goes where, since the polarity of the leads doesn't matter.

  4. 4

    When everything has been set up and you're a safe distance from the engine, have your helper crank the engine as you observe the multimeter's AC Volts readings.

  5. 5

    If the crankshaft position (CKP) sensor is working correctly, the multimeter will register an an oscillating voltage between 0.5 to 1 Volt AC.

    Now, to be a bit more specific: your multimeter will not register a steady AC voltage. Instead, the reading will jump between 0.5 Volts AC to 1 Volt AC continually as the engine is cranking and only when the engine is cranking.

Alright, let's find out if you have a bad crankshaft position sensor on your hands or not. Choose from the CASES below that best match your specific results:

CASE 1: The multimeter registered the indicated AC voltage with the engine cranking. This result indicates that the crankshaft position (CKP) sensor is creating a good CKP signal and is working fine.

If you have confirmed that the crankshaft position sensor is OK but your Ford still doesn't start, take a look at the following tutorial for more testing suggestions:

  1. How To Test A No Start Condition (Ford 4.6L, 5.4L).

CASE 2: The multimeter DID NOT register the indicated AC voltage with the engine cranking: This confirms that the crankshaft position sensor is fried and is the cause of your 'cranks but does not start' condition.

If you'd like to buy the factory original Motorcraft crankshaft position sensor (and save), check out the section: Where To Buy The Crankshaft Position Sensor And Save.

More Ford 4.6L, 5.4L Tutorials

To see all of the Ford 4.6L, 5.4L diagnostic tutorials, check out this index: Ford 4.6L, 5.4L Index Of Articles.

Here's a sample of the troubleshooting tutorials you'll find in the index:

  1. How Can I Tell What's Wrong With My Transmission? (Ford 4.6L, 5.4L).
  2. How To Diagnose Misfire Codes P0300-P0308 (Ford 4.6L, 5.4L).
  3. How To Test Ford 4.6L, 5.4L Coil-On-Plug Ignition Coils (at: easyautodiagnostics.com).
  4. How To Test The Ford MAF (4.2L, 4.6L, 5.4L) (at: easyautodiagnostics.com).
  5. How to test the 4.6L, 5.4L Throttle Position Sensor (TPS) (at: easyautodiagnostics.com).
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