It is possible to accurately test the crankshaft position sensor (commonly called the crank sensor) with just a multimeter. In this article I'll show you how.
Now, the test I'm gonna' show you here is not a resistance test of the crank sensor since the crank sensor can not be tested in this way. Instead, I'm gonna' show you how to test the crank sensor in action by manually cranking the engine and with your multimeter in Volts DC mode.
Contents of this tutorial:
You can find this tutorial in Spanish here: Cómo Probar El Sensor De La Posición Del Cigüeñal con Multímetro (at: autotecnico-online.com).
Tools You'll Need:
- Jack Stands
- 1/2 inch Ratchet Wrench
Important Tips And Suggestions
TIP 1: You'll need to lift the vehicle to gain access to the crank pulley. Use jack stands to hold up the vehicle. DO NOT trust the jack. Your safety is your responsibility, so take all necessary safety precautions that includes using safety glasses.
TIP 2: The test instructions call for you to manually turn the engine using a 1/2 Ratchet and the appropriate socket. Do not turn the engine with the starter motor. Using the starter motor will severely decrease the accuracy of your multimeter test results.
TIP 3: If your Chrysler vehicle starts, this test article will not help you. When the crank sensor goes bad, your vehicle will crank but not start. If it starts, the crank sensor is working.
TIP 4: You'll notice that the image (of the crank sensor) in this test article show it out of the vehicle, this is just to make it easier to show you the wires to be tested. On your vehicle, DO NOT remove the crank sensor to test it.
CKP TEST 1: Verifying The CKP Signal
The crank sensor is located on the transmission bell housing (on the side facing the fire-wall) and it's held in place by a bolt.
To set up the test, you'll need to unplug the crank sensor from its connector so that you can connect your multimeter's red test lead to the crank signal wire.
One word of caution: DO NOT remove the crank sensor from the transmission's bell housing. If you do, the sensor's air gap calibration will get lost (when you reinstall the crank sensor) and the sensor will get beaten to death by the flywheel's reluctor ring.
NOTE: The crankshaft position sensor must remain connected to its electrical connector to read its voltage signal. You'll need to use a back probe or a wire piercing probe to access the signal within the wire. To see what a what wire piercing probe tool looks like, click here: Wire Piercing Probe.
OK, let's get started:
Lift and place your Chrysler vehicle on jack stands. This will make it easier to gain access to the crank pulley.
Disable the ignition system. You can do this by simply disconnecting the ignition coil pack from its electrical connector.
Locate the crank sensor and disconnect it from its connector.
Now, remove some of the plastic wire loom protector and/or the black electrical tape that shields the three wires of the CKP sensor. Remove enough of this electrical tape insulation to gain comfortable access to the three wires it protects.
Place the multimeter in Volts DC mode.
Connect the red multimeter test lead to the wire identified with the number 1 in the image above, of the three wire connector.
The wire labeled with the number 1 is the signal wire that transmits the crank (CKP) sensor signal to the PCM.
Don't worry about the particular color this wire should be on your vehicle. You'll be able to identify it easily with the photo above.
Reconnect the connector now if you had to disconnect the sensor to set up your multimeter test lead. The crankshaft position sensor must be connected to its electrical connector for this test to work.
Connect the black multimeter test lead to the battery negative (-) terminal or a good Ground point on the engine.
When everything is set up, turn the crankshaft pulley by hand in a clock-wise direction while you keep your eyes on the multimeter.
IMPORTANT: Do not use the starter motor to crank the engine, since this will defeat the accuracy of this test.
If the CKP sensor is working correctly, the multimeter will register an ON/OFF voltage of 5/0 Volts DC.
ON is when the multimeter displays 5 Volts DC and OFF is 0.5 Volts DC.
NOTE: The key to seeing this voltage change is to turn the crankshaft pulley slowly and steadily.
Alright, let's find out if you have a bad CKP sensor on your hands or not. Choose from the CASES below that best match your specific results:
CASE 1: The multimeter registered the ON/OFF 5 Volts DC as the crankshaft pulley was hand-turned. This confirms that the crank sensor on your 3.0L, 3.3L, 3.8L Chrysler vehicle is working fine and not the cause of the no-start no-spark condition.
CASE 2: The multimeter DID NOT register the ON/OFF 5 Volts DC as the crankshaft pulley was hand-turned. This result usually indicates the crank sensor is fried. To be absolutely sure, I suggest making sure that the crank sensor is getting both power and Ground.
Therefore, the next step is to check that the crankshaft position sensor is getting power. This comes in the form of either 5 Volts or 8 Volts, depending on how old your specific Chrysler (or Dodge or Plymouth or etc.) is. Go to: CKP TEST 2: Making Sure The CKP Sensor Is Getting Power.