Engine Coolant Temperature Sensor Tests

Engine coolant temperature sensor circuit explained. The engine coolant temperature sensor is a variable resistor known as a thermistor. The PCM runs multiple tests on the sensor circuit to check for shorts and opens. I refer to a wiring diagram to create both faults while monitoring the sensor signal with a voltmeter and a scantool.
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I cannot guarantee against improper use or unauthorized modifications of this information. MR. DIAGNOSTECH assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. Use this information at your own risk. Any injury, damage, or loss that may result from improper use of these tools, equipment, or from the information contained in this video is the sole responsibility of the user and not MR. DIAGNOSTECH.

[@cristi9944]

A very precise and detailed explanation, thank you for deciding to share your experience. I am happy that there is still someone who also thinks about beginners. Thank you very much

[@MRDIAGNOSTECH]

You're very welcome!

[@johnngo341]

You have a hell of a way of teaching. Thank you and keep up the good work

[@Grunter123]

What a great explanation. Thanks for sharing.

[@u.e.3769]

One of the best explanations Greetings from Germany😊

[@MRDIAGNOSTECH]

Thanks! 😃

[@1231234abcab]

Good refresher course 👍🏽

[@MRDIAGNOSTECH]

Yes, thanks

[@patrickmoran6004]

The best explanation I've seen on KZbin. Thank you.

[@sheerwillsurvival2064]

Great video please keep them coming. Old school technician . Can you do some on pull up and pull down circuits and the difference in ground side switched and positive side switch. Little lost. Thanks

[@abdussamaddhodhat4551]

Thank you sir very very good explanation

[@MAZMSPBRA]

Amazing! Another great video for beginners and advanced technicians! Keep up the great work! I may have to enroll to your classes for a refreshment soon!

[@mekkibilal1372]

Great job thank you for the help

[@benjaminlevi7792]

Great information. Thank you 🙏🙏

[@patrickmoran6004]

Brilliant video. Could you do one on the camshaft sensor.

[@geoff3172]

Great video, many thanks for posting

[@journdiag7621]

Thank you for sharing your knowledge

[@Rekani-sq5nl]

Thanks for explanation, well done

[@ThunderbirdRocket]

Nice 👍🏼 ! 🔥 🧰 Thanks mate !

[@HS-fw2ed]

Very good job! Why doesn't the resistor inside the PCM create a voltage drop? Why, after that resistance, is the voltage still 5 volts?

[@MRDIAGNOSTECH]

When it is unplugged, the circuit is incomplete, and voltage is not used.

[@HS-fw2ed]

Thanks! 🙏

[@Jemimah-b1y]

This is a great job here. Please, I need your opinion on a BMW i'm working on. The issue is, at high temp, even above 120°C, the fan will not start(that is abnormal). Once you unplug the ects, the fan will come up(normal, showing an open circuit). The confusing part is that, there is no DTC and all measurements are ok. What is your take on this?

[@MRDIAGNOSTECH]

@@Jemimah-b1y I would do a voltage drop test from the sensor signal to DME and from the sensor ground to a known good ground. It might have unwanted resistance on the circuit.

[@Jemimah-b1y]

@MRDIAGNOSTECH Thanks, i've done all of these tests. the resistance on the signal wire is around 42ohms and sensor ground 18ohms, which I feel is a normal wire resistance. I began to suspect the DME, i changed the DME, but it was the same(fan not coming on). I tried to on the AC to observe if there would be a difference, NO! Just thinking, can a bad thermostat sensor be a cause?

[@MRDIAGNOSTECH]

@@Jemimah-b1y voltage drop using volts, not ohms. It should not exceed 0.100V.

[@Jemimah-b1y]

@MRDIAGNOSTECH woke up to see your response. Your responses are really insightful and helpful. Yeah, voltage drop btw sensor signal and Dme is 0.098v. with the ects unplugged, a measure btw the sensor signal wire and a good ground should give a 4.9v - 5.1v and a measure btw sensor ground and bat+ should give battery voltage(BMW manual) and that is what i'm getting. With the sensor plugged, i measure btw sensor signal(back probed), and ground gives 2.6v after an overnight sleep test. Pls where am i getting it wrong?

[@Max-j2r]

❤❤❤❤❤❤

[@ericornelas5488]

GREAT VIDEO!!