Switch Input Identification Variables

[@sambitar8448]

PAUL, you are a blessing to the automotive industry, thanks a billion

[@ScannerDanner]

They only get to see it once (live). They take notes in their books (my eBook), listen to the lectures, practice in the shop, then go in the field after graduation. This is where the real learning begins. Hopefully my book follows them and is a guide they reference for years to come (that was the intent of the book format). They have the theory, they know why (from my lectures), they just may need a reference to a test. It's all there in the book. No need to sit through the lecture again.

[@ScannerDanner]

It would be 0v with the switch closed (grounded) and 12v with the switch open. Even though there is a resistor, there is no voltage drop across it until the switch is closed.

[@صلاحالحراصي-غ1ض]

Mr Danner I got confused and my brain is "pulled aside" , not up not down 😂 Thanks a lot sir I like your character. Greetings from Oman 🇴🇲

[@ScannerDanner]

Hey guys Just wanted you to know that I increased the video time period to 45 days. It's not an owned version as some of you would like but its the best I can do at this time.

[@nancylewis7142]

OMG, it looks complicated. but good info, thank you Paul.

[@ScannerDanner]

I wouldn't argue that, but all switch inputs are monitored for this high/low voltage, so it wouldn't be any different with this design. If the computer expects to "see" high volts and it "sees" low volts it will store a DTC. and vice versa

[@PhattyMo]

Good Stuff. I'd call it a pull-up,just that the pull-up resistor is external to the ECU/whatever. It could be tricky to test,if you don't realize that the pull-up is external.

[@gokblok]

Seems to me that your example is merely a pull-down circuit, being that the computer voltage sense is *after* the load. I'm not sure about this "externally vs internally sourced" thing. What do you mean? What exactly is being sourced? The load? The ground? The 12v supply?

[@Amopower]

Hi Paul, I have to agree with another poster below. I bought Chapter 1 tonight and was surprised to see an expiration date, pretty small i might add, one month. I don't know what it would take to get a "members-only' area on your webpage, but the idea would be to have the purchased videos available to your username, basically forever, unless this video service you use now would let you extend the video expiration alot longer than a month. (what was your reasoning for the short time?)

[@yori131]

quick question is the pull down and the pull up the same thing as the computer providing the power and ground being pull down when the computer provides the power and pull up when the computer provides the ground

[@arishenao]

Es al contrario pull down es tierra o gground pull up es power

[@BMTroubleU]

paul, with this circuit what voltage would you find when the circuit is grounded? i supposed it depends on the resistor. would you expect 5v or is it going to be less seeing as its only for a sensor?

[@ScannerDanner]

its just about the cost and bandwidth usage. if I left them open forever eventually I wouldn't be able to afford to keep streaming them. and an owned download is not an option, too easy to copy and share. I can't totally prevent pirating but I am doing whatever I can. as for the 30 days, most of these Sections are only 2 hours long. So my thinking is you have 30 days to watch and absorb 2 hours of material as many times as you like, that is plenty. My students don't even get that.........

[@ScannerDanner]

prices are based on the amount of content in each Section. Go to my website and each section will have a description and price. only sections 1, 2 and 3 are complete. sections 4 through 23 will be completed in sequence over the next few months. Thanks for your interest.

[@BMTroubleU]

ok, so the resistor has to be large enough to drop all the voltage out of the circuit when grounded. fair enough. makes it easy for the control unit to detect i suppose. thanks mate

[@codybear56]

But there was a non-switched power feed, and a resistor. All of the switching took place after the resistor, and would pull the source voltage to ground. I am really not seeing how this is a pull up. For it to be a pull up, in my own mind anyway, is the switch closing would allow voltage to a sensor.

[@ScannerDanner]

A pull-down circuit is "internally sourced" by the computer. A pull-up circuit is "externally sourced". This is SUPER important to understand when troubleshooting a circuit like this. If this was actually a pull-down design, when I unplugged the trans connector, there would have been voltage on that signal wire. The fact that there was no voltage means one of two things. 1. There is a problem within the signal circuit 2. It is normal because it is a pull-up design. Make sense?

[@jameschiplen2843]

From what I was learned in an Isuzu diagnostics course this is a pull down circuit, the resistor is there to keep the voltage high, causing at binary output “1” until the switch is closed, causing voltage to be pulled low, giving you a binary output of “0”.

[@ScannerDanner]

automatic updates my friend. no need to buy it again.

[@zvonimirbobicex-4962]

simply put: sometimes a wire in the wiring diagram is basically a "computer voltmeter`s lead"...just measuring the volts on the wire it attaches to...and the switch /design is defined by those wires that run the current...so perhaps, maybe not a variable, after all ;)

[@marktirabassi7873]

To confusing lecture today