In this article I explain how it works and how to identify a CKP sensor (crankshaft sensor) for induction and Hall effect.
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Today I'm going to talk about a sensor quite common in today's vehicles which are the magnetic field detection either hall effect or voltage generation by magnetic induction.
The purpose of this sensor is to send signal pulses to the engine computer so that, depending on the frequency of the motor, it can calculate the speed of a certain part if it is for the speed of the wheels, or if it is for position by the signal pattern.
In order for the sensor to work, it needs a metallic (phonetic) cogwheel with or without a pattern and a permanent magnet that is usually part of the sensor or is in each pin of the cogged rude. You can see the following figure where the mounting method of the sensor. In the following figure you can see the aforementioned.
When rotating the gear wheel depending on the type of sensor will generate these two wave patterns. One square wave for the HALL effect and another sinusoidal for the inductive. See the following figure:
Then as you can see the idea of the sensor is to send pulses as the wheel rotates and with this the computer knows the speed, and if it has a pattern the wheel then calculates the position.
These sensors are used to measure:
-> Speed of the wheels for ABS.
-> Crankshaft position.
-> Position of the camshaft.
-> Positions of changes in automatic boxes.
-> And more ...
How does this sensor work?
Well I will not explain theorems, electromagnetic theories or anything like that ... hahaha. I'm going to talk about the final result, for example:
For the HALL effect sensor
When passing the tooth in front of the sensor, it will take its output to 0V or ground. This signal is maintained if the tooth is facing the sensor (active state). When passing the tooth, the internal transistor opens and will not terrify the output (inactive state).
For the inductive sensor
When passing the tooth "in motion" a variation in the field of the sensor is generated that destabilizes it, generating tension in the internal winding, then between the terminals of the sensor an induced voltage will appear.
Unlike the HALL effect sensor, even if the tooth is in front of the sensor, if it does not move it does not open induced voltage and therefore between its terminals it will dial 0V. This is because the voltage induced in the winding occurs only by destabilizing the magnetic field of the sensor.
Why is the CKP or CMP sensor damaged?
Generally these sensors are extremely reliable, the most common damages are due to cable faults, the sensor was placed very close to the gear wheel and it damaged it (it was eaten), as it is placed near the damper it falls long oil or grease and it hurts. Very rarely it is by circuitry or by overheating.
How to identify if it is the CKP that prevents my engine from starting?
Many times people quickly blame this little friend without judging first, that's why I decided to do an article where I detail some procedures to discard their failures and you can read it by clicking the button:
How to identify the type of sensor we have?
To perform this task, a multimeter measuring resistance is necessary.
If the sensor has two wires, it is inductive. But if you have three cables you should do the following test to clear up doubts. Place the multimeter in resistance measurement mode and perform the measurement as follows:
As you can see in the side terminals "depending on how you put the sensor" you will notice that in one it will mark resistance of approximately 1000 ohms and in the other it will give 0V. This is because the cable is shielded. Then the coil is between the terminals that make resistance.
For the HALL effect.
For this case if doing the procedure for the inductives no terminal gives resistance, you have in your hands a HALL effect sensor.
Anyway, seeing the following article can make a small effective tester that will let you know what type of sensor has and if it works or not.
Is it possible to test this sensor effectively?
The answer is yes. Many times the mechanics when the scanner throws them CKP failure replace it without first checking if there are connection problems or the cable is broken. The best thing in these cases before changing a sensor that is really good, is to do simple tests.
You can review the following article where I explain how to make a simple CKP tester to have at home or workshop.
It only remains to say that if you have any questions or suggestions you can leave it in the box below for questions.
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