Switch Input Bypass Testing - LED or Incandescent Test Light?

This was a clip of an SD Premium class I taught and was pulled from my Chapter 2 "Switch Inputs" playlist. Here is the link to this full length class www.scannerdanner.com/scanner...
ScannerDanner Tools:
www.scannerdanner.com/tools.html
www.amazon.com/shop/scannerda...
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.
Want even more diagnostic training? Whether you are a DIY trying to fix your own car, someone looking to become an auto technician, or a current auto technician that wants to get more into diagnostics, subscribe to ScannerDanner Premium www.scannerdanner.com/join-sc... There is a 14 day free trial.
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.

[@ScannerDanner]

This was a clip of an SD Premium class I taught and was pulled from my Chapter 2 "Switch Inputs" playlist. Here is the link to this full length class www.scannerdanner.com/scannerdanner-premium-chapters/chapter-2-switch-inputs/chapter-2-switch-inputs-full.html#chapter2-GMC-Acadia-live

[@AlexMartinez-xv1gh]

The amount of knowledge you provide is amazing. No other place does it 🔥

[@ScannerDanner]

Thank you so much!

[@calholli]

Someone needs to create a BOB style board that has several bulbs in it to use for loads. an LED, small incandescent bulb, and a 2A bulb and a 4A headlight, etc.... We need a compact load widget toy

[@calebbouchillon]

I've had this same thought. Integrate it into a set of those retractable leads and it would be gold

[@7minnow]

The Best Mr P

[@user-px6ul4zw5r]

Awesome thank you so much I have a service manual on the way so I can look at wiring diagrams but I'll do as you say... Thanks again much luv from Luzerne county

[@whitetiger8652]

Thanks Paul.

[@cardiaglexia995]

Perfect Paul .

[@thestoryteller526]

Thank you ❤ for your videos.

[@mostlymoparih5682]

Good stuff. Happy Motoring.

[@amarabdelli487]

Thanks, good idea

[@lupedelacruz4152]

Thank you teach

[@smokey3829]

Voltage is equal to Current (I) times Resistance (R). Nice troubleshooting 👍

[@sdel2694]

Hey there. Love the vids they helped me locate a short in driver side headlight. I was wondering, could a damaged ground cause a parking/standing light to stay on 24/7 and kill the battery?

[@ScannerDanner]

Hard to say without way more info on what that wire is and what it is connected too, but most likely not

[@careyautorepairs]

Cool

[@rodvan-zeller6360]

Of topic, have you used a thermal imager for finding exhaust leaks and bad injectors? Thank you in advance for your answer.

[@lvr1028]

What I learned recently is that LEDs vary in resistance if you load different amounts of voltage. It has to do with semiconductor properties, that might apply here 🤷‍♂️

[@ScannerDanner]

The main point I'm showing is that LED bulbs have much higher resistance than conventional incandescent bulbs and generally will not trigger a switch input circuit properly. Thanks!

[@lvr1028]

@@ScannerDanner of course! I was offering an explanation for why this might have happened. I've been watching your videos for a long time. I bought a small handheld oscilloscope not too long ago that helped me find an intermittent injector pulse dropping out on my 1991 supra turbo. I used your son's celica video to understand the G and NE signals, but in the end I just cleaned the ECU ground and it seems to have done the trick. Pre OBD2+intermittent can be a pain but i've learned a lot. Thanks to you :)

[@sheerwillsurvival2064]

👍🏻

[@user-px6ul4zw5r]

Hello. I was wondering if you had any known good waveforms for a 2008 GMC Acadia coolant temperature sensor???

[@ScannerDanner]

That would be known as a thermistor. 2-wire sensor that has a signal and a ground. Signal voltage will range from .5 to 4.5v depending on the temp of the engine. Step 1 for you would be to measure voltage (plugged in and backprobing) with the engine cold and the same temp as the outside air. Then compare what voltage you have with a temp chart. That I don't have. You'd have to search for that info

[@FORDTECH313]

Hi Paul, I always watch your videos and you usually respond to my messages. I tried other channels, but no response. I hope you see this message. I was wondering if you could recommend a scope that is affordable I know Snap On scanners come with scopes they’re higher and ones and also there’s a Pico scope but unfortunately, right now I cannot spend the amount of money. I was wondering if you can recommend an affordable one thank you

[@luispedraja8489]

ayy danner its me again lol, soooo i watched your video on control testing on ignition systems. but this is weird.. i remember you saying the feed wire should be brightly lit consistently. but after testing my feed and control wire they behave the same? as in, they get bright and dim continuously. now , i dont know if i should consider that valid. again.. crank no spark. power coming in out of the injectors and coils. ohh yeah! and the injectors behaved the same too.

[@ScannerDanner]

If coil positive and negative look the same, you have no control. Focus on your inputs next if the injectors are doing the same thing

[@luispedraja8489]

@@ScannerDanner danner i am so sorry. i think after all this time i found my issue. was recently studying about finding shorts etc, idk i was bored. anyways i took the intake manifold off and inspected the starter. the positive battery cable to the starter was barley makingg contact. and, 1/3rd of the harness which was ground was suppose to attach to the starter. i attached it to the engine block instead. is that why im having no spark and slow cranks like this ??? i cant believe this

[@danieelop]

👍👍👍

[@Stoically_]

Okay so, I’ve always been unsure how to use a test light as a “ switch “ , so I want to make sure I understand this. Only if it’s a pull up design can you do this? And why didn’t you use the 12 volts that’s apart of the circuit ? Would that not have worked?

[@ScannerDanner]

Pull-up or pull-down circuits! Ask yourself, what does the switch do? Does it pull the signal voltage low or does it pull the signal voltage high? Then connect your test light with the correct polarity to do the test. Make sense?

[@Stoically_]

@@ScannerDanner thank you

[@dougmacqueen1679]

So when are we going to see "Be the computer" ScannerDanner shirts?

[@ScannerDanner]

That's a good one! Sending this to Caleb now 😀

[@Zage55]

now how about on a pull down design?

[@Mikes_Repair]

Put your test light lead on a good ground.

[@ScannerDanner]

Come check out my classes I offer on my website www.scannerdanner.com/join-scannerdanner-premium.html

[@xDMG15x]

I’m curious as to why you didn’t get the result you were expecting with the LED test light. Does that LED test light give the same result in both directions? Like, if you put the clip end on the grey wire and probe the battery positive instead, do you get the same result? By definition an LED should only work in one direction, if it works both ways then there is some extra circuitry that makes it happen, and maybe the path the current takes has a higher resistance than the path it takes when the polarity is reversed?

[@ScannerDanner]

The LED test lights with a single alligator clip have circuitry within them that they will light with either polarity. The reason for the lower voltage is because of the higher resistance of the LED bulb/circuit. Also with this being a voltage divider type of input circuit there is another internal resistor in the computer you are not seeing.

[@xDMG15x]

@@ScannerDanner thanks for the info. I always thought the resistance of an incandescent bulb would be higher than LED. So when I switch an old bulb for an LED one, theres more resistance in the circuit and thats why the ecu thinks theres a bulb error, the voltage drop is higher than expected. Damn, all these years i thought the error was because the led bulb didnt draw as much current 🤦🏼‍♂️ and when you get LED hyperflash the load resistors are actually to reduce the resistance of the circuit, not to increase the circuit load?

[@ScannerDanner]

@@xDMG15x it doesn't draw as much current (higher resistance) so you were right on that point

[@natersalad889]

Do you ever have a sale on your hard cover book? I want to get one but man $100 is alot for me lately....

[@carguy1312]

Hey bud - just wanted to encourage you to job hunt a bit. No one in this industry should sweat over a $100. I feel fortunate to have found a boss who values his people. We should hold them to that standard by utilizing the wheels on our toolboxes when they won’t.

[@natersalad889]

​@carguy1312 I appreciate your comment and understand what your saying but it's not that, it's more of being a single income family because we have twins and a 1 year old all under 5, so wife has been stay at home momma until twins are in kindergarden next year. We were blessed with twins, but also had to decisions along the way to be able to make it work for us, which limits our household income being a homeowner and family of 5, thanks for caring enough to reach out though... honestly...

[@ScannerDanner]

​@@natersalad889we don't really run any promos for what we offer. The eBook may be the way to go for you as it's half the cost? But I certainly understand the position you're in and it's awesome that your wife is able to stay home with your children. Email me at [e-mail] and screenshot these messages and I'll see what I can do for you.

[@carguy1312]

@@natersalad889 as the parent of a special needs person the world doesn’t want, I hear you. The struggles a parent faces are nothing short of heroic. You got this!

[@AustinSellers-wl6nz]

Hey Paul, I’m just curious if you answer questions on a problem I’m having? Please let me know if are. I’d be happy to pay for your time if needed. Let me know how we can communicate thank you!

[@ScannerDanner]

I help when I can but cannot offer back and for messages, emails, etc for tech support. Not when 500000 other people want the same thing. Here is the message I send people when I can't answer something without research... Let's move this to my forum www.scannerdanner.com It is free to join and we can definitely help you. I have 28k global members and hand picked moderators who've been with me for years and know my material inside and out and are there to help me help you guys. It is just too difficult to offer back and forth messages here on KZbin with stuff like this and we also can't share pictures and images here like we can on the website. Hope to see you there!

[@Santiago_Ordonez_]

It would be great if you had a channel for exclusive members here on paid KZbin, of course it would be excellent.

[@ScannerDanner]

I used to but in 2017 yt shut down all the individual paid channels when they started YT red. Since then I've moved all of my content to my website. Currently it sits at 550 videos with half of those being all of my classroom recordings. You can join here for $11 a month. www.scannerdanner.com/join-scannerdanner-premium.html

[@Santiago_Ordonez_]

@@ScannerDanner What stops me are the subtitles, because I don't completely master English.

[@ScannerDanner]

@@Santiago_Ordonez_ we have English subtitles on every video now

[@dwilliams6346]

Hi Paul. Have you ever done a scope test to diagnose a faulty reluctor ring? Thanks

[@ScannerDanner]

Yes, I have a few case studies/classes where I've shown this

[@dwilliams6346]

​@@ScannerDannerJust came to realise mine is the cause of a 4 year mysterious P0335 fault code. Changed the Pulse Ring last November to try and fix it but unknowingly put the faulty reluctor ring back on. Kicking myself. No information available on it being the cause of a crankshaft sensor not learning problem, even though they're used on many GM vehicles.