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How to Test a Crankshaft Position Sensor Using a Multimeter

Dan Ferrell writes about do-it-yourself car maintenance and repair. He has certifications in automation and control technology.

1. Coil 2. Soft iron 3. Magnet 4. Electrical connector.

1. Coil 2. Soft iron 3. Magnet 4. Electrical connector.

Depending on your particular vehicle make and model, a failing or bad CKP can produce one or more of the following symptoms:

  • Hard to start
  • Cranking, no-start condition
  • Start and stall condition
  • Rough idle
  • Hesitation
  • Poor acceleration
  • Increased fuel consumption
  • Misfires
  • Check Engine Light On

However, problems in other systems (for example the fuel or ignition systems) can also produce some of the same symptoms. So, it is important to test the CKP to better diagnose the problem.

Although it's recommended to test a CKP sensor using an oscilloscope, this is not a common tool for many car owners or DIYers. Still, you can troubleshoot the sensor using a digital multimeter (DMM), whether your engine uses an inductive or Hall effect type sensor.

That's what you'll do here using this guide. Keep in mind, though, that you still need the electrical values for your particular vehicle make and model, to locate the sensor, identify wires, and, if necessary, replace it.

You can find this information in your vehicle repair manual. If you don't have this manual yet, you can get a relatively inexpensive aftermarket copy through Amazon. Haynes manuals come with many images and step-by-step maintenance, repair, and troubleshooting projects for many systems in your vehicle. So you'll recoup the small investment in no time.

Index

1. What is a CKP Sensor Used For?

2. How To Tell If You Have an Inductive or Hall Effect CKP Sensor

3. Troubleshooting a CKP Sensor

Checking the Wiring and Sensor

Testing an Inductive Type CKP Sensor

Testing a Hall Effect Type CKP Sensor

4. What if My CKP Passes the Test?

5. Replacing the CKP Sensor

The CKP sensor monitors crankshaft position and engine speed.

The CKP sensor monitors crankshaft position and engine speed.

1. What is a CKP Sensor Used For?

In general, the CKP monitors piston movement and crankshaft position. It also helps the computer monitor engine misfires and engine speed. The computer uses this information to adjust ignition timing and fuel injection.

However, a CKP sensor endures heat and vibration during engine operation. This eventually takes its toll and the sensor or its circuit may fail.

As with other emission related sensors, the car's computer may store a diagnostic trouble code (DTC) pointing to a problem with the CKP sensor, or the sensor's circuit, like:

  • P0315
  • P0335-P0339
  • P0385-P0389

If your engine uses a camshaft position (CMP) sensor, you can also see a related code:

  • P0016-P0019

So it is important to troubleshoot the CKP when you suspect CKP problems to make sure the problem is with the sensor, the circuit, or one of the components in the system it works with.

The next sections will help you test your CKP sensor using only a digital multimeter (DMM), whether your engine uses an inductive or Hall effect type sensor.

2. How To Tell If You Have an Inductive or Hall Effect CKP Sensor

Basically, most vehicles on the road today use one of two types of CKP sensors.

Inductive (magnetic) CKP sensor:

  • May have one or two wires
  • Mounts in front of a rotor or reluctor wheel
  • Produces its own AC voltage signal

Hall-effect CKP sensor:

  • May have three or four wires
  • Mounts in front of a rotor or reluctor wheel
  • Generates a digital (square wave) signal
  • Requires an outside power source and a ground to produce the signal
You can use a digital multimeter to test the CKP sensor.

You can use a digital multimeter to test the CKP sensor.

3. Troubleshooting a CKP Sensor

Many problems with the CKP sensor can be located on the wiring harness or the sensor's connector. So make sure to carefully check them before starting to troubleshoot the sensor itself. But first, locate the sensor.

Depending on your particular vehicle make and model, you can find the CKP sensor:

  • mounted on an engine front cover or timing cover, near the crankshaft pulley or behind the harmonic balancer.
  • somewhere around the middle of the engine block.
  • under the starter motor.
  • on the rear of the engine, at the bellhousing of the transaxle near the flywheel ring gear.

If necessary, consult your vehicle replace manual to locate the sensor on your specific model.

Checking the Wiring and Sensor

Many times, a failing or inoperative sensor comes from a bad wire or connector. Make a visual inspection of the harness and connectors between the sensor and the PCM or ignition module.

  • Check the wires for damage
  • Check for loose wires
  • Check for loose sensor mounting bolts
  • Check the electrical connector for damage
  • Check the sensor itself for signs of damage
  • If necessary, check the air gap between the sensor tip and the rotor. Consult your vehicle repair manual for the specification.
  • Remove the sensor and check it for metal shavings or filings stuck to the sensor's magnetic tip.
  • Inspect the sensor reluctor wheel for damage.
If your vehicle uses a distributor, disable the ignition system to crank the engine.

If your vehicle uses a distributor, disable the ignition system to crank the engine.

Testing an Inductive Type CKP Sensor

The following steps give you an example on how to test an inductive type CKP sensor.

However, make sure to consult your vehicle repair manual for the electrical value specifications and, possibly, a recommended way to test the CKP sensor in your particular model.

  1. Unplug the CKP sensor electrical connector.
  2. Set your digital multimeter to DC voltage scale using a low range.
  3. Turn the ignition key to the On position, but don't start the engine.
  4. Touch the DMM black lead to ground. This can be a clean surface on the engine, a metal bracket or the battery negative (-) post.
  5. Touch the DMM red lead to each of the sensor wires on the harness connector you just unplugged. One of the wires should produce around 1.5 volts; otherwise, the sensor is not receiving a reference voltage, and needs to be fixed.
  6. To prevent the engine from starting:

    • Disable the fuel system by removing the fuel pump fuse or relay.
    • Or disconnect the ignition cable between the ignition coil and distributor.

    If necessary, consult your vehicle repair manual. This will prevent the engine from starting.

  7. Set your digital voltmeter to a low range on the AC voltage scale.
  8. Connect your meter leads to the sensor pins. Make sure to keep your meter lead wires away from engine moving parts during this test.
  9. Have an assistant crank the engine for a few seconds while you watch the meter's readout.
  10. The sensor should produce a voltage pulsing signal. If you don't see any voltage pulses, replace the sensor. Compare your results to the manufacturer specifications. Consult your vehicle repair manual.

You can check your inductive CKP sensor's resistance:

  1. Set your DMM to the Ohms scale.
  2. Unplug your CKP electrical connector.
  3. Connect one DMM lead to one of the sensor pins and the other DMM lead to the other sensor pin. It doesn't matter which.
  4. Turn on your DMM.

    • The readout should indicate a resistance value, usually between 200 and 2000 ohms, depending on your particular vehicle model.
    • Compare your results to the manufacturer specifications. You may find the specification in your vehicle repair manual. If out of specification, replace the sensor.
    • If the readout is infinite resistance, the sensor has an open in the circuit;
    • If the readout is zero ohms, the sensor has a short circuit.
When disconnecting the ignition cable from the distributort, ground it to the engine with a jumper wire.

When disconnecting the ignition cable from the distributort, ground it to the engine with a jumper wire.

Testing a Hall Effect Type CKP Sensor

Testing a Hall effect type sensor is best using an oscilloscope. But not many DIYers own one. Still, you can use a DMM to test this type of CKP sensor in your vehicle.

Although you won't see the high and low voltage graphic and frequency you see on an oscilloscope readout, you'll get the average voltage coming from the sensor, which will give you an idea of its operation.

  1. Remove the fuel pump fuse or relay to prevent the engine from starting during this test.

    • If your engine uses a distributor, you can unplug the center ignition cable and ground it to the engine using a jumper wire.
    • If necessary, consult your vehicle repair manual.
  2. Unplug the CKP sensor electrical connector.
  3. Set your DMM to DC volts and to a range of 20 Volts.
  4. Touch the DMM black lead to the black wire on the harness connector.
  5. Touch the DMM red lead to the red (power) wire on the harness connector.

    • You may need to check the wiring diagram for your particular model, if the CKP sensor uses wires of different color to identify the ground, power and signal wires.
  6. Turn the ignition key to the On position.
  7. Your meter should read between 5 and 13 volts. Consult your vehicle repair manual for the reference voltage value for your particular model.
  8. Turn the ignition Off and plug back in the CKP sensor to the harness connector.
  9. Touch the DMM black lead to battery negative.
  10. Then, using the meter red lead, back probe the black, ground wire at the harness connector or CKP sensor.
  11. Ask an assistant to crank the engine for a few seconds. Your DMM should register about 200mv to 300mv.
  12. Now, touch your DMM red lead to the green (signal) wire on the harness connector or CKP sensor.
  13. Crank the engine for a few seconds. You meter should register around 300mv. This is an average voltage value of the signal the CKP sensor produces.

If necessary, compare your results to the specs in your vehicle repair manual.

Although not as common, your car's computer can also be at fault here.

Although not as common, your car's computer can also be at fault here.

4. What if My CKP Passes the Test?

Even if your engine experiences the symptoms of a bad CKP, it doesn't necessarily mean that your sensor, wiring or a connector is bad. The problem could lie with those components it communicates with.

Perhaps there could be a problem with the ignition control module (ICM) or even, although not as common, the PCM itself, depending on the particular configuration for your model. If necessary, consult your vehicle repair manual.

5. Replacing the CKP Sensor

In general, replacing a CKP sensor is a pretty straightforward operation. However, on some models you may need to remove one or more components to access the sensor. Consult your vehicle repair manual.

  1. Make sure the engine is cool and the ignition switch is in the Off position.
  2. Disconnect the negative (black) terminal from the battery.
  3. On some models, you may need to raise the front of the vehicle, and secure it safely on jack stands, to gain access to the sensor.
  4. Unplug the CKP sensor electrical connector.
  5. Unscrew the mounting bolt(s).
  6. Remove the sensor from the engine.
  7. Match the old sensor to the new one.
  8. If your sensor comes with an O-ring, apply a light coat of oil to the ring before installing the sensor. This helps to seat the sensor correctly, helps the sensor produce the correct signal, and prevents oil leaks.
  9. Install the new sensor in place and tighten the mounting bolts.
  10. Plug the sensor electrical connector.
  11. Connect the negative terminal to the battery.

On some engines, you need to set the correct gap for the sensor. Follow the instructions that come with your new CKP sensor or your vehicle repair manual. The next video gives you an idea on how to replace a crankshaft position sensor.

This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.

Questions & Answers

Question: What if the sensor tests good and gets power but the coil will not fire?

Answer: There could be a problem with the ignition coil or the ignition module, depending on your system's particular configuration. You may need to consult your vehicle repair manual and diagram for this.

Question: My CKP sensor is intermittent, but yesterday I managed to get the following info: the output signal went up to 11.2V whereas it was 0.4V. After the engine warmed up it went back to 0.4V. Why does it do this? Is it a faulty sensor?

Answer: A common CKP sensor fault comes from the internal coil or wiring. A wire can break but still make contact. Temperature gives it away because it makes the coil expand (heat) and contract (cool). It can be very annoying sometimes because whenever you test it, it gives good parameters. Usually, the best way to test this type of fault is to warm up the sensor in hot water and compare your reading to the sensor when it's cool. Hope this helps.

Question: Why would my car only start on the second crank?

Answer: Make sure you got good connections between the battery and the starter. Check this other post. It may help:

https://axleaddict.com/auto-repair/How-to-Use-Volt...

© 2019 Dan Ferrell

Comments

Wambura Kinyunyi on March 15, 2019:

Am mechanics but this is good stuff , I like it

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