Oscilloscopes...the show me, and advice thread

[mrjaw14]

Greetings! I haven't seen a thread about this, and I know there's got to be some mechanics and other technical people who use Oscilloscopes.

I'm needing to track down an issue with class II serial data in my truck to verify if my IPC is bad. basically I need to "scope" the cls II wire on my IPC and reproduce my complaint and see if I'm getting serial data on the wire during the failure.

I've done some research on scopes and found out that it really depends on the signal you're going to measure as to what scope you need. I'm thinking about a USB scope to plug into my laptop, but I'd be up for a small hand held unit as well. I imagine it'd be hard to use a bench scope on a car...maybe I'm wrong?

So A) if any of you have used a scope to look at the serial data lines in a vehicle what kind of scope do you have, and what settings do you use?

and B) if you have a scope show it off!

 

[Alchymist]

Greetings! I haven't seen a thread about this, and I know there's got to be some mechanics and other technical people who use Oscilloscopes.
So A) if any of you have used a scope to look at the serial data lines in a vehicle what kind of scope do you have, and what settings do you use?

and B) if you have a scope show it off!

Not exactly for automotive use, but it certainly would do the job on serial data lines:

 

[2manytoyz]

I have an old 2 channel oscilloscope. It originally had a built in battery pack, but it long since died, as did the built-in charger. I now use an external 12V gel cell battery when going mobile.

Mine came from an electronics salvage yard many moons ago.

 

[Steinmetz]

I use an old Tektronix 465B.

You are merely looking for the presence of serial data on the line during a failure and not decoding it?

 

[LEVE]

I use a HP 54601a 4 input scope. It meets my audio/computer/auto needs. Here is my little jewel:

 

[Alta_Racer]

Not a true scope, but I have a Snap-on Vantage PGMM (power graphing multi meter). I use it as my first tool pick when checking data at most all sensors. It has pre-set functions that will get you close to the right setup for checking most things. These can be found used on E-Bay for reasonable price, but make sure it has at least version 4 update, as it give better scope speeds. A lot of people complain the screen is too small.
I had an incident, that let the smoke out of mine, and immediately bought another from E-Bay, cant work without it.

When I really need a lab scope, I use the snapon Modis, it has a great 4 channel lab scope. It will also do ignition scope, has a built in PGMM and is a scan tool to boot. It has quite a nice screen.

I also have a Pico scope module, that plugs into my laptop. It is extremely fast, but it is always a bother to set it up to test things. I do use it to have close looks at very fast signals, like crank sensors at higher than idle speed. (not a common test)

 

[mrjaw14]

I use an old Tektronix 465B.

You are merely looking for the presence of serial data on the line during a failure and not decoding it?

Yes not looking to decode, just if its there or not or weaker than it should be. I think I need a minimum of 5 MHz bandwidth and 10 Million samples a second sampling rate. This sound right?

 

[Steinmetz]

Yes not looking to decode, just if its there or not or weaker than it should be. I think I need a minimum of 5 MHz bandwidth and 10 Million samples a second sampling rate. This sound right?

The Tek scope I mentioned has 100MHz bandwidth. It is an analog scope. It (or an equivalent) would work fine here. I've used it to sample digital signals on serial lines before.

 

[FiendFX]

just get the old snap on vantage on ebay

 

[oldldh]

If you're only looking for data, you're going to see two lines about 5 volts apart, the signal doesn't have to be synced, data is data...

The KISS (Keep It Simple Stupid) formula works...if you loose the signal, the preceding component is probably bad...You can't repair a chip, you replace them...

Remember, most humans don't need to decode data, if it's there, the chip is working...(You need a clock signal, Vcc, and an enable signal...and the data rocks on...)

Happy troubleshooting...

 

[richfinn]

I,ve got an ancient MAC ET2020 dual channel scope (made by Tektronix), I think it,s only 8mhz but it displays a nice crisp signal, It is capable of measuring network data signals, dual channel is best for this type of work as you can see both high/low at the same time.

 

[kythri]

Is there a good "Automotive Oscilloscope Use For Dummies" guide somewhere out there?

I've got a Hitachi V-1100A 100mhz oscilloscope that's been kicking around for a while, and it'd be cool to put it to use...

 

[GTA Matt]

Pico scope seems to be the best PC based scope out there for automotive use. Snap On also has it pretty well nailed down with the Vantage Pro, Verdict and Verus. The Verus is a 4 channel, while the Verdict is a 2 channel, but is wireless. I have a Verdict. It doesn't get much better then having a car hooked up and running across the shop and sitting at my toolbox surfing the web, watching the graph while waiting for a hiccup.

As far as your serial data issue, sometimes you can use a simple voltmeter on the data line. If you suspect the IPC is bringing down the data line, you can hook up to it and simply unplug the IPC and see if the data bus responds. Or if you are having an issue, you can simply begin unhooking components until the problem is no longer there. Seen pennies in a cd player bring down the whole data bus. Unplug the radio and everything comes back online.

 

[joebiodiesel]

Greetings! I haven't seen a thread about this, and I know there's got to be some mechanics and other technical people who use Oscilloscopes.

I'm needing to track down an issue with class II serial data in my truck to verify if my IPC is bad. basically I need to "scope" the cls II wire on my IPC and reproduce my complaint and see if I'm getting serial data on the wire during the failure.

I've done some research on scopes and found out that it really depends on the signal you're going to measure as to what scope you need. I'm thinking about a USB scope to plug into my laptop, but I'd be up for a small hand held unit as well. I imagine it'd be hard to use a bench scope on a car...maybe I'm wrong?

So A) if any of you have used a scope to look at the serial data lines in a vehicle what kind of scope do you have, and what settings do you use?

and B) if you have a scope show it off!

Because the modules in your truck probably all take turns talking on the Class II line, a scope isn't going to help you diagnose a bad IPC. How would you know which signals are made by the other computers on the bus?

Joe

 

[Drew_flux]

I think for your use, your on the right track with the usb scope idea.

 

[GTA Matt]

Figured I would share this. Some screen captures from my Verdict. The victim is a 07 BMW 330I with a misfire on cylinder 3 as well as a cylinder 3 coil code. I hooked up my low amp clamp to the power wire and backprobed the signal wire. Unfortunately, the code set so fast due to the bad coil that the pcm shut down the coil. I was able to get some cool readings from the cylinder 2 coil however. Red trace is coil amperage and green trace is coil voltage and the spark line. At idle the coil is fired 5 to 7 times per cycle. Off idle, it is a single fire system. Its nice being able to tell what a coil is doing without getting your hands dirty. On fords I do this through the fuse box in the car.

at idle

off idle

 

[GTA Matt]

Well, I figured out how to send screen shots straight from my scanner to photobucket so no more crappy camera phone shots. Here is a screen shot of the above BMW.

And this is a shift solenoid on an 02 VW GTI. Transmission is acting wonky and setting a code for this solenoid. Red trace is current, green is voltage. With VW's track diagram I wasn't sure what wire was power and which was ground with just the diagram I pulled. Obviously I wound up on the power side, but it doesn't matter because obviously it is getting signal (ground). You can see the current ramp up, then drop off for a second as the solenoid opens and then continue to ramp up. Diagnosis: solenoid is good, with the mileage on the car, its getting a new trans.

 

[danski0224]

I've got an old Tektronix with a whole lot of vacuum tubes in it

 

[greasemonkey44]

good captures matt
mine are always ugly; i use an older scope

 

[texasprd]

Is there a good "Automotive Oscilloscope Use For Dummies" guide somewhere out there?

I've got a Hitachi V-1100A 100mhz oscilloscope that's been kicking around for a while, and it'd be cool to put it to use...

Interro used to publish a waveform guide book. The scope-setup info was all based on their handheld labscope, but the patterns shown would appear more or less the same on any scope (I'm a DIYer with an old SnapOn Vantage). It really helped me see how, in many cases, the relationship between multiple signals is key.

Interro is now Omitec - you could contact Omitec (http://www.omitec.com/us/contact-us/) and see if they still offer that guide (shown here:http://www.omitec.com/us/arrange-demo/, or try to find it on ebay. Also, Omitec has a waveform section on their website and you can find some decent tutorials on the web.

You might also check aeswave.com and see what they have - they are the best place I found for automotive scope accessories.

 

[richfinn]

Is there a good "Automotive Oscilloscope Use For Dummies" guide somewhere out there?

I've got a Hitachi V-1100A 100mhz oscilloscope that's been kicking around for a while, and it'd be cool to put it to use...

www.techtopics.co.uk.

Look in the shop section

 

[sandog]

my portable 200mhz dual channel oscope. Love it. I use it to diagnose circuit boards when i am either building them or fixing them.

 

[joecon]

Motor use to make a manual with different patterns in it to show you
what they should look like.

 

[PrecisionTools]

My current...