Thermistor-Potentiometer comparison and the 5v reference circuit

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Suggested playlist to help reinforce this topic
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For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available at www.scannerdanner.com as an eBook or paper book.
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On ScannerDanner Premium I will bring you right into my classroom at Rosedale Technical College. You will find page for page lectures taken right from my book as well as exclusive classroom type case studies. What is so special about these classroom case studies? I pull live problem vehicles directly into my classroom and we troubleshoot them in real time, using and applying the theory and testing procedures we learn during the classroom lectures. There is no better on-line training of how to troubleshoot automotive electrical and electronics systems anywhere!
Disclaimer:
Due to factors beyond the control of ScannerDanner LLC, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. ScannerDanner LLC assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. ScannerDanner LLC recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video. Due to factors beyond the control of ScannerDanner LLC, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained in this video is the sole responsibility of the user and not ScannerDanner LLC.

[@mikejohnson2750]

What a teacher !You can just hear the passion in his voice. He almost seems like he's just taking his time,like this is too easy!

[@ScannerDanner]

I have hundreds more just like this if you are interested. Thanks!

[@ozzstars_cars]

This video was simply fantastic with the explanation between thermistors and potentiometers. No more to say but thank you Sir Danner.

[@cuzodakid1]

Danner is one of best teachers ever

[@5Dale65]

You said it bro

[@danielgarcia9095]

Yup yup

[@cobbysparks9891]

Preach!

[@seftonplayer32]

He is the best teacher!! The others out there only show you what they do, they don't tell you the why!!

[@ryangwin1318]

Found this and now I own the book. This stuff is gold for anybody truly interested or working in the field. Im a diy-er but Im a gear head and it drives me nuts not to have any electrical skill set. Thanks for helping make sense of this mess so I can actually become more competent and not have to swap parts when I run out of options for troubleshooting.

[@ScannerDanner]

Thank you Ryan! You've seen the light lol.

[@michaelluciano1980]

Putting this into practice at 40:00 to the end was the perfect way to wrap all this up. Thank you

[@xristosmaglaras7077]

Just perfect a always...Thank you for being out there and teaching us..the DIY guys and not only..God bless you Mr.Danner.

[@grahamlucas6033]

Thank you for devoting the time to bring us this valuable info in such an professional and informative manner Mr Danner

[@ScannerDanner]

Thanks for watching!

[@baxrok2.]

Awesome lesson! Reinforces what I read in my book and surely nice to hear you run through it firsthand. Thanks!

[@amadoterte1714]

Good day Mr Paul Danner. You are the only teacher who showed me the internal circuit of a PCM ( the high resistance bias resistor, the 5v reg, the transistor driver, the voltage sensing circuit VSC, power side switching, ground side switching). Because of this, I fully understand now how the PCM works. You executed a teaching process with high degree of competence. Thank you sir. God bless.

[@ScannerDanner]

Thank you!

[@andrewk778]

Always interesting and informative. Quite simply, you are the best. Thank you for sharing.

[@arthurfricchione8119]

Very informative video Paul. Truly enjoy your class. Thanks for the info.

[@israelzunigamascorro9300]

great video, Mr Paul. I really love to see it. It is a fantastic information. Thank you for sharing your knowledge. blessing

[@saturninorizal4293]

thank you ScannerDanner for sharing your skills and knowledge.....God always Bless you...

[@turningwrenchesautorepairm5017]

You did a great job simplfying these circuits.

[@golfnut533]

You are a knowledgable chap and have a good teaching method. One question I have: Even though you recommend checking the fuse to the computer, if it is blown then it should not just be replaced with a good one as something obviously caused it to fail downstream and this then then ties in with your checking components and wiring etc as you have shown. Excellent video. 👍

[@ScannerDanner]

Of course! 100% if you find a blown fuse, you need to find out why that fuse blew. This wasn't a lesson on locating a short to ground though, that's another class in itself. Make sense? Thanks!

[@edasplaces6451]

Thank you for sharing your knowledge to us Mr scanner danner

[@iemandjwzz4614]

Thank you so much for this video. It is so very well explained!

[@spelunkerd]

After 5 years I came back here for a review. Like quality wine, it ages well over time, ha ha.

[@ScannerDanner]

Thanks brother

[@sithembisoduze8728]

Great teacher, gonna buy the book soon.

[@01sidiropoulos]

I really got something here, excellent lesson with details from start to the end ❤️ it!!! Keep it up!!

[@ScannerDanner]

Awesome! Thank you so much.

[@nickayivor8432]

KNOWLEDGEABLE Sir ScannerDanner Thank you tutorial great 👍 Take care Sir ScannerDanner From Nick Ayivor from London England UK 🇬🇧

[@Bushougoma]

31:23 The LM7805 has over current protection (it will stop supplying additional current to the output when you hit the current limit around 1 - 1.5 amps this will cause the output voltage to drop this is called entering constant current mode), overpower protection (the regulator will shut down if the IC gets too hot due to either excessive voltage on the input or excessive current draw on the output that the heat sink can't dissipate) and short circuit protection they're designed to be pretty bullet proof actually. Not impossible to kill but difficult. Most modern regulators linear and switching contain this protection circuitry internally.

[@ScannerDanner]

Thanks for the info!

[@arsalanarif1780]

Hey Paul. Your family must be very lucky to have you in there life. You are too damn smart.

[@susie2275]

Absolutely great book!!

[@Pablo_Automotive]

Great class Paul thanks for share your book is really nice.

[@ScannerDanner]

Thank you Pablo!

[@phoenixautodiagnostics4209]

thanks for sharing Paul.

[@ScannerDanner]

Thanks for watching!

[@victorlewis8970]

Yep, love all this information.

[@marktirabassi7873]

Victor M Coria cute

[@joneskey3950]

anyone watching video who's not in the automotive repair industry? Great video.

[@d-brosslgarage8566]

Great video. Thank you sooooo much. Sir.

[@henryevasco6512]

Thanks a lot Danner I learn a lot.. From nz

[@liviu2004]

Some ECUs do monitor the 5V reference. They even have 2 split 5V regulators feeding redundant circuits, like pedal accelerator sensors and throttle position sensors. However I am not familiar with the US vehicles to comment. I've bought your book and really looking forward to read it.

[@ScannerDanner]

Like this one kzbin.info/www/bejne/q6rRlImwlK10qqM Thank you so much!

[@jacoponono8179]

Magneto-resistive ABS sensors also work the same as a thermistor. There is a current limiting resistor up-stream, and they need to be unplugged to measure the reference.

[@braol]

Great video, as usual. I would just like to point out that if you unplug a sensor and your 5v comes back it may be the wire rubbed through, not a bad sensor. Had a 3.5 charger with multiple codes for sensors that shared the same 5v reference. Unplugged the EGR valve and the 5v came back. Had I just called the sensor I would have been wrong. Instead I drove it and didn't make it 1 mile and all the codes came back. Checked my 5v and it was gone again. The harness was rubbed through on the back of the engine leading up to the EGR valve

[@ScannerDanner]

For sure, there are always variables like this. Thanks for sharing! What you are describing would be similar to this video kzbin.info/www/bejne/q6rRlImwlK10qqM

[@marco320033]

Bruce Oliver nu

[@arthurbright1625]

Love the video very good point just because a relay clicks does not mean it is good

[@Elchin206]

Best teacher👍

[@SuperMarioDiagnostics]

Good stuff 👍

[@mohamedeln]

Thank you very much

[@MechanicTechnicianRepair]

Good. Tech. Nice. Video. Saludes. Noel. Matute. Grasia

[@alibatebi2161]

thanks for video very informing. but what happen when switch input is closed,according to this diagram there would be two 5v ref on both side of (ECT,IAT,TPC) resistor

[@pankajtyagi6697]

Thankyou very much

[@danstark462]

It open my eyes. Good

[@ScannerDanner]

Awesome

[@buzzbuzzard9469]

Thank You

[@cnhz01]

This was really helpful. I was confused on one point; that is the fact that the signal ground (or whatever name you give it) is connected to the negative end of the battery through the chassis of the car. I didn't realize this on my first watching and so got very confused. Hope this detail helps someone.

[@cnhz01]

Leo Chia 1 hour ago (edited) Hey Paul! Returning to this after 2 months and am understanding much more than I did initially. I have a question: Does the Voltage Sensing Circuit have a high resistance resistor (relative to the fixed resistor) located in the circuit just before it connects to ground to allow a consistent voltage drop across the fixed resistor and not create a short? Thanks so much!

[@cnhz01]

I think you mentioned it in another video; it is also implied here as you mention that the voltage sensing circuit does not support current flow. But just wanted to check to make sure.

[@babychannel7674]

Just subscribed to the web page... I like it. I like it a lot

[@ScannerDanner]

thank you so much! look forward to hearing from you

[@babychannel7674]

@@ScannerDanner up and at em early. I'm catching hell but I'm learning. Taking the harnesses and engine out of sonoma, and putting it in my other. I cut some wires before looking at your channel man 😂

[@cinouye82]

Good after Mr. Danner, Been watching your videos for about 1 year now. You’re awesome. Quick question that has me confused. In looking at this 5v reference circuit, it is a parallel circuit I believe. If so, how does 1 leg of the circuit take out the others? I thought that was the benefit of parallel circuits to not be affected by an open. Thank you!

[@del9936]

to answer your question ,if the maf sensor shorts to ground then for protection of the circuit the voltage regulator shuts down the 5 v ref circuit until the short is removed , a direct short to ground would cause a high amp draw from the pcm and possibly blow it internally

[@philiprambow4657]

Great video, one question at minute 36 you state to make sure you disconnect test light before measuring ohms, would not the thermistors also need to be disconnected

[@ScannerDanner]

No need to because the computer is already unplugged, therefore the thermistor signal/ref circuit is already isolated. Make sense?

[@johnnymalicoat754]

Is your typical hotwire maf sensor a drop down sensor? Other words can i test it with my scan tool by grounding my 5v reference wire the same way i can a hall effect crank sensor?

[@Zage55]

nice i learned a lot👍🏽👍🏽 but im stuck with an issue what if a signal wire from a three wire pressure sensor has full battery pack voltage?

[@ScannerDanner]

If you have battery voltage on a 3 wire psi sensor or potentiometer, you most likely will be reading this same battery voltage on all 3 wires plugged in. This is a bad main computer ground symptom.

[@paulfiebke3909]

Wish i could read skomadicks like you do . Im working on a 08 toyota Camry and i had to buy a book haynes and it sucks

[@monangamoki7572]

I wish I could join your classes!

[@ScannerDanner]

If you cannot in person, you can take this class on-line from my website. It is called ScannerDanner Premium www.scannerdanner.com/join-scannerdanner-premium.html Hope to see you there!

[@dumisaninkomo2531]

that awesone lm following all the chapters and i would also want to confirm about the issue of certificates do u give online certificates

[@ScannerDanner]

I do not offer anything like that unfortunately. Just good solid training.

[@likezdislike]

what if I hook up my dvom test lead to 5 volt ref.wire and the other test lead to positive side of battery and I get 7.6 volts? is it normal or I have shorted ecu or wire?

[@dannypalmer7701]

What is 5 volt reference? Does the PCm send a ground to some sensors?

[@boybravo689]

Sir may I know the pin out of the transistor regulator 7805 coz I google it the left most pin is input and the center pin ground and the right is output how come that in your diagram does not match the pinout tnx Sir

[@mohammedcherifi9206]

Are all cars equipped with the map tps vaf and ckp sensor share the 5v ref circuit or there are other designs ?? Thank you sir Paul i always watch your videos greetings from Morocco ❤️❤️

[@ScannerDanner]

it is pretty standard yes (that the 5v ref is shared), there are some variables though, like some newer models will have of to 4 different 5v regulators This one had two different ones kzbin.info/www/bejne/q6rRlImwlK10qqM

[@mohammedcherifi9206]

@@ScannerDanner thank you sir Paul

[@brohdyknopp613]

Can you send 12 volt up the signal wire with test light since it does support current also to the ground wire I'm guessing the ref you'll pull down

[@ScannerDanner]

Why would you intentionally send more voltage that what is typically on that circuit? I mean, you can, and won't hurt anything, but there is no need to do that, you have a 5v ref available to you to do the wiring integrity test. Make sense?

[@nicholaasupindi8923]

Good stuff..where can I get that book please

[@ScannerDanner]

From my website at www.scannerdanner.com Thank you!

[@Giorobot]

I've been trying to buy your book since 8/20/2020 on Amazon but it's out of stock where can I buy it ? I got this fever

[@ScannerDanner]

From my website at www.scannerdanner.com Thank you! You'll be redirected to AESwave who is my exclusive paper book provider. If you have any trouble email us at [e-mail]

[@IamReadyToRock]

desde Peru 👍👍👍

[@mototechno834]

Hi Paul..Do both diesel and petrol cars have MAP sensor???

[@ScannerDanner]

yes, but not all gas engines use a MAP

[@jharrison6557]

At 34:17, could you explain why you would have 0 volts with the TPS plugged in, and why it would be shorted to ground if there was 5 volts present with it unplugged?

[@ScannerDanner]

What I am describing in this section, is if you have 0 V on a 5 V reference circuit and you unplug one of the sensor's and it returns to 5 V you have a shorted sensor

[@jharrison6557]

ScannerDanner... got it. Watched your Honda element video with the shorted MAP sensor and came back to this vid, makes total sense now. Your channel is super helpful, as is your book. Keep up the awesome work.

[@ScannerDanner]

Perfect video to watch to hammer this home.

[@pigeonsil240sx]

my question is how do we know if the signal/control wire is supposed to be sending out a signal to pcm or supposed to receiving a signal from pcm? is this just something we need to learn from each sensor or is thisn info in factory service manuals?this confuses me and very important for me to know.

[@ScannerDanner]

Copying and pasting my comment. In case you missed it. BTW, you only need to ask once. I see all the comments on every video. Signal wires are input circuits and are being "watched" Control wires are output circuits and are being controlled. Come join my classes and I can teach you this stuff for sure! I offer a 14 day free trial, so come see what I have. Based on your question, I'd recommend starting in my chapters 2 and 3 playlists. www.scannerdanner.com/join-scannerdanner-premium.html Hope to see you there!

[@SmittySmithsonite]

If you think this is great, wait until you subscribe to ScannerDanner Premium! Great stuff man! This one video just tied everything together in my head ( finally, lol! we that grew up in the 80's may have damaged our brain cells a bit ... some more than others ........ like myself ... :D ). THANKS, for the millionth time. :)

[@siahmedsidali277]

Good morning sir thanks for your lessons , sir could you say the meaning of WOT . THANKS SIR .

[@ScannerDanner]

Wide open throttle (WOT)

[@siahmedsidali277]

Thanks sir .

[@dannypalmer7701]

What is limp mode How do you take it back out of limp mode!

[@ka-techarastrmac633]

Hi can anyone say potentiometers and thermistors? Which sensors are potentiometers and which sensors are thermistors? Thanks in advance. Sincerely yours.

[@ScannerDanner]

A potentiometer measure the position of something. Whether rotational or linear. A thermistor is a temperature sensor.

[@Airman..]

SD Can fix a brand a new car at the dealership

[@faroukkhan6777]

Thanks Paul ,, im getting 2.25volts ref on my pencil coils,, everything else 4.89..refs. Honda?????2006

[@ScannerDanner]

There is no 5v ref on an ignition coil

[@faroukkhan6777]

@@ScannerDanner thank you sir,,so the 2.25 at pencil coils is ok ,,crank no start some where else,?? Just a quick note I had a crank no start on Honda frv ,,was a faulty speed sensor,, same crank no start key light flashing, engine light on.

[@ScannerDanner]

@@faroukkhan6777 I assume you are taking this measurement during cranking and that it is a 3 or 4 wire ignition coil. They will use a 0-4v trigger signal that is an on/off square wave to control the coil. Your voltmeter may be averaging that signal. But then again you're really not giving me enough information about what you're doing, what you're missing, the conditions of when you're testing and what made you think the 5v ref circuit goes to an ignition coil. Also, I've never heard the term pencil coil

[@faroukkhan6777]

Thank you sir,,2006 Honda Jazz 8xspark plugs car was driving fine no problem,,try starting,, key light flashing engine light on,read with topdon 800bt OBD2,, normal read no problem,,, now say error in communicating with ECU????? Thanks kindly farouk

[@sevllaroberto7527]

i meant in spanish (real bad spelling)above on the comment.

[@Mechanicsville804]

Thank you! Hebrews 9:27 King James Version 27 And as it is appointed unto men once to die, but after this the judgment:

[@jjyotajj1826]

First