How to test a 3 wire sensor and circuit - simple tools.
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- Опубликовано: 19 дек 2021
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Here we show you a quick and easy way to test a 3 wire sensor and it's wiring with basic tools. There are variables to this test.
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Technical information supplied and used under authorisation from Hella Guttman - used for teaching purposes only, not for redistribution or copying, partially or otherwise.
Thanks for watching :)
Steve
* Disclaimer: Neither Simply Diagnostics, SimplyDiag Network Ltd, nor Steve Scott accept any liability for any loss, injury or damage to any person, property or vehicle as a result of techniques, tools or methods shown on this channel. Always follow the manufacturers instructions and abide by all local and national laws regarding safe working and environmental hazards* 
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A classic and smooth flowing tutorial.
I will always shout for some more!
Thanks for the videos mate. I'm a mechanic that's trying to improving in electrical diagnosis and scope use and find your videos very informative!
Great to see you back on RUclips Steve! Nice simple and informative video
Look forward to getting back up to the hub next year 👍
Good to see you in action again Steve!Thanks for the lesson 👍
Then comes the intermittent problems. Still, your way is a quick check for circuit integrity.
Merry Christmas and Happy New Year!
Great to see you back at it mate. Suffering with tooth ache that day but didn’t realise I was pulling such funny faces 😂. Was a top day. Hope to catch up soon👍
Recognise that voice anywhere! See you on the next installment of the diag tech course mate 👍
AWESOME video, thank you for posting, that workshops well equipped, i wish mine were like that!! please keep up the great work, well appreciated 🙂
This is absolute gold
very good video, explains everything thank you for sharing
Great video! That signal wire integrity testing method is really quick and clever.
good to have you back mate . noticed on the wiring diagram one is pull up and one is pull down
Well spotted, I was keeping it simple for this video 👍
Brilliant to see you back
Very informative, thank you for sharing.
Great to see you Steve. Merry Christmas & Best of the New Year when it arrives. Thanks for sharing... Cheers.
Awesome to see you back Steve. Keep posting 👊
Thank you posting this very helpful video, please continue , also where can i get all the wiring diagrams from? , i have older AutoData but they are essentially useless, as do not cover many models and predominately for older cars.
Thanks Steve, merry Christmas
Great job mate
Great to see new videos!
Great tutorial well explained
Great video Steve, great to see new content 🙏👍
Awesome knowledge mate another excellent video
Sweet, 👍 enjoying watching your videos.
What a great video I hope you have a merry Christmas
good to see ya back on youtube , great video ,hope ya well , nice one steve
Brilliant thanks!
Great to see sir.
Great to see you back Steve. I was only just thinking last week..'We haven't seen Steve for quite a while' You must've been a busy man. Have a great Xmas and New Year mate👍🇦🇺
Brilliant having wiring on the big telly steve
Good to see you mate
Please have a wonderful Merry Christmas and be safe
That darn bug is kicking butt in the UK and USA
Thank u sir👍
Awesome video 👌 👌 as usual. Thank you for sharing it with us . Have very Happy Xmas and well deserved break 👍👍👍👏👏👏✌❤🍀☘
Glad to see you back, with one more great video. Ì was thinking couple of weeks before,that we haven't seen you for long time, I checked your channel, and I was unsubscribe!!!!!!
Of course, I subscribed again immediately, but someone told me that if one channel haven't upload a video for long time, the RUclips by itself, start to unsubscribe people from that channel. I don't really know if it's true, I just leave this comment, maybe some other people, had the same issue.
Great video and well explained. Just a note some vehicles also use digital sensors for pressure using changes in frequency instead of voltage changes.
Indeed they do, we also have sensors now using the SENT protocol that is a digital data signal and not frequency.
This is where rule No1 comes in: What am I testing?
@@SimplyDiagnostics yes I have seen/diagnosed these before, 100% agree we need to know and understand the circuits we are working on.
Again great explanations cheers 👍
Hey Steve!!! So great to see a new video from you! What an amazing setup! Love to see you doing well my friend! Sending big hugs & love! Merry Christmas to you and the family! 🎄⛄🎅 🤶 ❄ 🎁 🤗🤗
Thanks Cuba, good to be back, merry Christmas to you and yours 👍
Excellent video! I've got a Smart CDI 45 bhp which I was ripped off on. Got various issues but can't get to the bottom of them. Mainly low flow at the egr and an iat circuit code. Car drops into limp mode constantly. Got a new egr and enough vacuum to lift it and no vacuum leaks. However, I've back probed the MAF and have 4.99V ignition on engine off at the loom side. Plugged in the volts drop to 2.32 ignition on. Start the car and the volts are 3.66 at idle. 3.4 volts at 2K revs and 3.1 volts at 3K revs. At idle my reader displays 6 g/s which seems high for a 799cc engine. Got any ideas please? Cheers.
Great tutorial Boss . now when is the next one!
damn impressive shop,
Hello there is this the same for Hondas or more specific Honda S2000 crank sensor? Best regards!
Great video, only bit I don't really understand is bat positive to the signal through the test light. This shows 5v on live data but is this actually 12v but the ecu can only read as high as 5v?
I can only guess but it seems to be a analog sensor, so it was just at the upper limit because it was equal or more than 5V and the ECU doesn't care about higher voltage.
Scary sht. Might fry an ecu in some cars? Dropping 12v into 5v line?
You can also pull bias voltage down with your finger one hand on bias and one on chassis/ ground
EricO style 👍
How are you plugged in for the live data? I have a P0190 intermittent fault. J have 5v Nd ground. No volts on ignition on from the connector but when engine started between 1-× volts. Car usually can do 4 miles then fault. The 3 pin sensor at times stops showing the readings hence the fault but im lost how to fix it
👍
HI I have a 2009 vx astra 1.4 petrol car had misfire hole burnt centre of no 3 piston fitted new piston chain kit etc
had 1 code stored for lambda bank 1 sensor 1 circuit new sensor has fixed that fault
any quick easy test i could do to make sure the car is not over fuelling car is starting running spot on atm but little apprehensive to take it out on the road
any advice greatly appreciated
👍
Good to see you on my screen again you have been missed very much in my opinion
Hi there
Just want to ask. What voltage should you have on signal with KOEO. I thought it should be 0.5v or there abouts
Thank you
As always great video showing test methods
Hi Haroon, it depends on application, each case is different.
👍👍
Don't really need the DMM so long as you've got an incandescent test light that'll glow at 5 volts. Has to be incandescent because some pull down signal circuits will flow enough current to light an LED.
Exactly 👍
Great video thanks, nice refresher. Had a question if you are missing the 5v reference can you supply the sensor with 12v instead of 5 from battery positive and now see if the sensor works? to sell the time to find out why the ref is missing and confirm sensor is ok.
Did it recently with a voltage generator to supply the 5v and that worked but wondering about making that test easier when a voltage generator isnt handy.
No, you’ll likely fry drivers or devices
Thanks I bought a little hand held voltage generator so I’ll use that when it happens
I wouldn't recommend, safer to do it through a testlight or a 5v low amp supply specifically designed for the job.
Great thanks yep I bought a portable voltage generator can do 20ma 0-10v should be good for it
@@SimplyDiagnosticsCan I ask how does using a test light make it safe to put 12v in to a 5v circuit so it doesn't fry ecm?
Hi Steve
Whats the benefit of this compared to backprobing? Or are tou trying to see if the sensor its self is pulling the bias down? Also would like to know where to grab them test leads they look a good job
Great question, back probes can introduce a pin fitment variable, my test leads are either from the hubitools kit available from Diagnostic Connections or the breakout kits from Warwick test supplies. 👍
@@SimplyDiagnostics awesome thanks for that pal
Do you have the 5v limiting adapter on the power probe battery clip for your test light?
No Mark, the testlight acts as a current limiting device so for this particular application its relatively safe.
Steve lad. Been a while 👍🏻
What if your signal wire is less than 5 V?
Dodge caliber signal volt is 3 V
Why does signal wire only show 5 volts when it’s plugged in to 12 battery volts please scratching my head , awesome to see you back
Purely because it's programmed to see 5v as the upper limit and therefore shows it as it's max value. Hope this helps. 👍
Yes thank you glad to see you back
So the signal must be 5volt
Good to have ya back can u send a link to the test light you used on ya amazon shop plse Steve
www.amazon.co.uk/shop/simplydiagnostics
@@SimplyDiagnostics is it the otc 3633?
There are 2 OTC and a cheaper version
@@SimplyDiagnostics is the otc one you used on that test the number i gave plse Steve?
No mate, it was the cheap chinese one
Where and how can i get wiring diagramthanks stev
If you've s bm-trouble-u.......you'll find the diagrams on tyres ista software.
If you've expensive diagnostic equipment they'll be in that.
If you've none of the above.....internet
سلام زمان مانشرت وين هل غيبة
I understand the theory, but I always feel some trepidation about plugging a 12v source into a signal wire back to PCM; less so if ground Vref or bias ... for the signal wire, this circuit carry very little detectable current via the sensor resistor ... 120mA light may make possible a100X the kind of current the wire may carry ... Do you think there may be any concerns justified? And do you think this would work with, say, a 30mA digital light??
I've personally never had an issue and no, an LED or digital light isn't a big enough load to pull down some bias voltages so may skew the test.
@@SimplyDiagnostics Excellent vid nontheless and very valuable to keep the test in the toolkit. Thank you!
In a nutshell, what exactly is bias voltage?
Bias is a virtually zero current voltage on a circuit that an ECU can use to detect a circuit fault ie open or short.
@@SimplyDiagnosticsalso called pull up voltage and is why the ecm will throw a “voltage above normal” when the sensor is unplugged (6.5 bias voltage on a 5 v reference sensor). Because the bias voltage is higher than expected?
Why is the signal value showing 5v on the screen when it's got 12v up it backside?
Great question, the ECU is programmed to evaluate up to 5v so even though the voltage is higher it will register a maximum of 5v. There are variations to this but this is the norm for most.
@@SimplyDiagnostics lovely, so it's safe to feed 12v into the ecu when checking the signal wire by watching the signal value.
I've literally just changed a 3 wire sensor this morning, the old faulty exhaust back pressure sensor on the mazda 2.2 skyactive engine, it's now got the mazda upgrade sensor kit on it.
Anyways one more thing, is the 150ma incandescent bulb test light categorically safe to use to test the signal wire to the ecu, there's no chance of over loading the ecu on that pin.
Personally I've never had an issue doing this with my testlamps. Check the current draw of your testlight before trying it. 150mA "should" be safe on most circuits - there are exceptions.
Hello. Can you help me please. I’m trying to test the 5V circuit of a Sprinter Van, EDC16. How can I check the ECU is working ok? What I’ve done is place a load in the circuit 2K ohms, same as ten boost sensor, the voltage pulls down to 3.5v, does that mean it’s faulty?
the wiaring diagram is from?
Hella HGS
Who needs college
errr,,me, and a few others too 🙂
Completely understand what you're doing but why are you putting 12v down a 5v signal wire?
Surely youd use that known good 5v supply at the plug & not force 12v down it 😂😢
Closeup camera work is essential and you failed the viewers. You waisted my time.
Thanks for the feedback
Well, now you will upload your own perfect video, right?!