In this article I show you how to build a CKP or CMP automobile sensor tester. Simple and very practical.
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As explained in my article How a CKP sensor works, these sensors are very common in the vehicle and many times where they are located because they are somewhat difficult environments, they get wet, the cables move a lot ... in fact for the treatment they are given , they come out very good.
Now, when these sensors fail, it is usually not so much due to internal problems but rather due to loose cables, dirty connectors, false contacts ... Then here I propose a small tester of position sensors of the inductive or HALL effect type .
This tester differs a bit from those found on the internet, since it incorporates the use of a transistor to amplify the inductive sensor signal in a way that is easier to see, and therefore easy to diagnose.
Without further ado, here is what you will need:
-> C1: An electrolytic capacitor of 10uF and 16V.
-> R1: A resistance of 10k ohm.
-> R2: A resistance of 680 ohm (this is the correct one, the one of the video does not).
-> A 9V battery or a transformer that up to 12V continuous.
-> D1:A rectifying diode 1N4007.
-> Q1: A general purpose PNP 3906 transistor.
-> LED 1: A normal green LED.
-> Alligators and cables for the connection.
Connect the components as indicated in the following figure. You can do this by directly welding the components or using a bakelite that comes perforated.
he functioning is quite simple. The diode 1N4007 receives the signal from the inductive CKP, then, the diode array, 10k ohm resistor and capacitor what they do is store (since the diode prevents the current from flowing back to the sensor) and slowly drain the transistor to the Low voltage coming out of the inductive CKP sensor. The latter amplifies the voltage so that it lights the LED longer so that it is easily visible.
In this way, with this arrangement it is not necessary to scrape, hit strongly or mistreat the sensor to see the led on.
It is quite simple to use since it only has three connectors which work for all sensors that are of the inductive or HALL type.
For inductive sensors
For inductive sensors it is used as follows:
-> Identify the terminals where the sensor windings are. See article How the CKP sensor works
-> Connect the red alligator (+) to one of the sensor's coil terminals.
-> Connect the white (test) alligator to the other free coil terminal of the sensor.
-> Touch the tip of the sensor with a ferrous metal piece that can be attracted to a magnet in a pulsating way.
-> See if the LED turns on and off in harmony with the movement of the metal part.
For HALL effect sensors
These sensors need power to operate which makes our tester by means of black and red alligators.
In this case I suggest trying the following combinations, it does not matter that they fail since the sensor as almost all the sensors of the car are protected.
Try the first connection combination and bring a ferrous metal piece to the tip of the sensor and see if it turns on the LED.
If it does not, try the second combination and repeat the previous procedure. If the LED does not turn on we have that the sensor is damaged.
As you can see it is quite simple to do the tester and test the CKP sensor with HALL effect or inductive. It even works for speedometers, speed sensors for ABS.
Here is a video of how I did it.
Well, I hope you find this simple but effective sensor tester CKP and CMP useful.
How to know if the CKP is guilty of not starting my engine?
In this article I explain some procedures on how to clear this important question:
How to know if the CKP is the culprit
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