Intro to the Automotive Scope,Basic Theory and Uses in Auto Repair

Intro to the Automotive Scope,Basic Theory and Uses in Auto Repair


all right on the flat rate master today we’re talking about scope basics DSO digital storage oscilloscopes what are they what are they good for and basic introduction so a scope is basically voltage over time graphed so you can see what’s going on now I’m sure every technician has a DV om pretty standard kit for most technicians digital volt ohm meter the difference between a DV om and a scope is several factors for instance the sampling rate how often it actually looks at the signal a scope has a much faster sample rate when it sees what’s going on a DV om has a very slow response time if you’ve ever used a DV om that is auto ranging you know sometimes there’s a little bit of a time difference between when something happens and when it responds that’s the sampling rate now a little bit of history back in the day for my age you remember the big box scopes those were oscilloscopes but they were not storage they didn’t have digital storage they were just scopes and if you’re old enough to remember them you probably don’t need to watch this video but what they did is very similar to what current scopes do they just do it with a much lower resolution screen slower sample rate and they were big bulky and kind of temperamental but almost every shop had one oddly enough I don’t know why every shop doesn’t have a scope in the shop they should have do you remember back in the day after snap-on put out some very nice scopes like the Consular to they brought out something called the Vantage now the Vantage is not a scope it is a graphing multimeter a lot of guys love those tools and they were good for what they did I mean they allowed you to see the voltage over time just not as high of a sampling rate as a scope but it was a good introduction to the idea of a scope now those are long since dead a lot of guys love them and will keep them alive buying spare ones on eBay for spare parts greens everything I mean they the guys that love them are almost a cult now after that they came out with the Vantage Pro which actually is a scope now the sampling rate on that is much better than the original Vantage intensive being a scope only to channel the Vantage Pro was great for its time limitations our interface screen and if that round that same time they brought out the motifs now the motifs is what I cut my real scoping teeth on it was a good scope for the time but you know snap-on has limitations and we’ll get into that in future videos but snap-on limitations are based on sampling rate and how they capture the signal one of the biggest drawbacks of a snap-on scope is actually if you’re not right on it all you can do is zoom out you can’t zoom in to a capture so if you didn’t get enough detail in a capture on a glitch you’re kind of messed up there’s options nowadays there’s tons of options you’ve got the 80s scope you’ve got of course Pico you still have snap-on now snap-on if you’ve got a snap-on scope it will do most everything you need to do in this in the field in the automotive repair shop it has its limitations especially on canned networks where it doesn’t exactly do as great of a job as it could kind of a nitpicky thing of that tool a scope now I’ve driven on here two waveforms basically a Hall effect sensor real simple signal now you’re diagnosing a car you’ve got two cam sensors I’ve got a cam sensor code and you want to look for things like sync and that kind of stuff or you want to look for like this where the signal just drops out again voltage over time I did a simple waveform we’ll get into a little more about actually comparing waveforms later on but it’s important to understand what a waveform looks like simple waveform on-off circuit nothing real special about it but again you see it flatline and then you might see it come back well the computer is going to see that a DV om is not and that kind of signal you need a simple scope test leads back pinning probes or piercing probes nothing real fancy about it there’s other tests where we’re going to get into where you require special adapters but simple way for setting up the scope is one of the things that snap-on really does excel at they have a whole section of their all of their tools to help you set up the tool they will set up the graph for you with all the parameters the voltage setting the time setting or as they call it sweep to give you advantage along with pin outs they will give you directions on how to hook up great for a beginning technician now will tell you a great tool to learn on is the Vantage Pro you can find them nowadays on eBay for five hundred eight hundred dollars get you into the use of a scope give you those helping hands to kind of guide you through if you don’t have a guy like me in the shop to help you figure it out now simple test you can do just like this with just those leads now more advanced testing you’re going to need some some tools now if you want to do a cranking compression test where you use a high amp or low amp clamp to see if the engine is cranking over evenly you’re going to need a high ampere a low amp clamp clamp clamp high amp clamp one of the advantages of the Pico is the option of a high amp clamp easily adaptable to the tool the snap-on kind of got it by either the low amp clamp and kind of backdoor it either with a low amp clamp and go to the voltage settings instead of the preset clamp settings for a low amp clamp to do a cranking compression you can do it but it’s a little more back door instead of right up front those are getting a little more advanced now it’s not a hard test to do but it’s a little more advanced and I’ll pop up a little picture of it behind me so you can see what a cranking compression test is basically all we’re looking for is even now if we’re not even then we need to sync to a source now generally when I do a cranking compression I’ve already kind of suspecting compression issues so I’ll synch it to a cylinder now I was doing a known good so I wasn’t worried about it but you can either use a always want to use spark simply because it lines with the compression stroke so you can figure out firing order figure out what cylinder is bad and you all you got to do is put in your firing order from what sonar you sink to and it doesn’t matter by the way what sonar you sink to all you got to do is go this is none this is lines up with you know cylinder number 4 this is you know 5 7 2 whatever all you got to do is lay out the firing order you figure out what cylinders are not contributing you know really good test to short cut base engine problems now obviously after that point you need to go into further diagnosis you know compression tests leak down to us all that kind of stuff but it’s a good shortcut to oh well tuneups not going to fix this car I need to do something else a cranking compression test is a great first step with a drivability complaint you know instantly that the cylinders are all contributing equally now equally can be an misnomer if you’ve got an engine that all cylinders are low compression well crank and compression is not going to give you a good idea of that but it will find uneven compression one of the biggest best things for a scope is cam crank correlation now when you’re getting into scoping and you’ve got a vehicle with the drivability problem and you suspect it’s out of time which is becoming more and more common nowadays with timing chains you know it’s not exactly easy to pop the covers off and look at the timing belt and see it’s off it’s a lot harder so with cam cranks correlation you can take a known good now we’re gonna get a known good part in a little bit but you can compare what you took off the vehicle and go it’s off I know I’ve got a known good signal on this picture I know I’ve got a known bad picture on this one it’s off if you know at that point it’s time to do a teardown and probably you know put a timing chains actuators or whatever you need into it but it’s a great way to instantly know we’ve got a problem one of the biggest benefits of a timing you know let’s just say you’ve got a customer that they’re kind of questionable about how much they’re gonna spend on that car do you want to invest in taking off valve covers intakes you know lining up cam marks crank marks and oh yeah we’re not paying for that with whereas with a cam crank correlation you’ve got twenty minutes in a finding a known good and comparing it and you’re done they know they’ve got a timing issue they’re not willing to spend the money on it you get your hour you’re done whereas if you tore down you might have hour and a half two hours into it depending on the engine I’ll have 20 minutes into it depends on the engine so that’s one of the advantages of using his scope in a day to day shop a lot of guys go I you know I don’t need a scope there’s really important times when you need a scope now the last one we’re going to talk about is network diagnosis if you’ve dealt with modern vehicles you’ve probably dealt with something pulling down a network you know the can signal flatline in something like that and again I’ll pop up a known good capture it’s important to understand that you know in diagnosing those vehicles especially can networks you really need to look at the signal you need to figure out what’s going on with that signal once you understand the network topography how its situated in the network you can figure out exactly what module is the problem a lot faster than if you don’t this is something I have struggled with for a long time being in a high production shop you know going from the modus to the ultra losing a laptop I’ve lost a lot of known goods over the years but there’s resources out there you’ve got Pico themselves you’ve got IAT n you’ve got Facebook groups network network with fellow technicians find out if they’ve got a known good on the vehicle you’re working on you know have them email it over if it’s a Pico scope capture which by the way if you want to play with picoscope software it is free to download they’ve got a demo mode so if you go on i-80 in and somebody has uploaded a Pico file raw file you can pull that into your software and play with it and look at it and see how it how the Pico software works allowing you to actually manipulate it so let’s say you’re using a snap on and you need to manipulate it so it looks closed in the same x basis of what you’re dealing with on the snap on you can put the time base so it very similar to what you’re looking at so I hope you like this introduction to DSO scopes if you did give me a thumbs up make sure you subscribe to see the rest of the series on using scopes we will be hooking up and scoping vehicles and helping you guys hopefully learn about scopes so I hope you like this video if you did give me a thumbs up comments are always appreciated and as always thanks for watching and I am the flat rate master


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