PicoScope 7 Automotive
Available for Windows, Mac, and Linux, the next evolution of our diagnostic scope software is now available.
basic questions
basic questions
I keep looking in on the forum with the intention of asking some what are most probably basic questions...usuall things that go through my head when im reading material on the site..im never sure where to start.. im not a professional mechanic and the forum seems to be populated with people who are fairly proficient in the use of scopes , so in the absence of a section for real amateur users I just give it a miss..
I am shortly going to have the use of a garage for a while and in line with the advice I was given and a desire to do it, im hoping to get some work done and some stored waveforms of various sensors on my lr defender which seems to be running well atm so its an ideal opportunity get and store some good examples...
a little bit of past experience reminds me half the battle with a scope is been able to access the various sensors... is it feasible to access them at some other point in the wiring harness other than at the sensor itself if the wires can be picked up.. say next to the ecu if thats where they end up and can be identified.. I appreciate some of the obvious drawbacks in terms of the possibility of faults existing in the connecting wiring and possible damage to insulation to make a connection ,but those aside will the waveform likely suffer in quality... I don't see that but thought I would ask... I have some 4mm tube connectors I was even thinking of making permanent scope connections to some of the sensor circuits, again is that feasible...I hope im asking in the right section..
cheers
Andy
I am shortly going to have the use of a garage for a while and in line with the advice I was given and a desire to do it, im hoping to get some work done and some stored waveforms of various sensors on my lr defender which seems to be running well atm so its an ideal opportunity get and store some good examples...
a little bit of past experience reminds me half the battle with a scope is been able to access the various sensors... is it feasible to access them at some other point in the wiring harness other than at the sensor itself if the wires can be picked up.. say next to the ecu if thats where they end up and can be identified.. I appreciate some of the obvious drawbacks in terms of the possibility of faults existing in the connecting wiring and possible damage to insulation to make a connection ,but those aside will the waveform likely suffer in quality... I don't see that but thought I would ask... I have some 4mm tube connectors I was even thinking of making permanent scope connections to some of the sensor circuits, again is that feasible...I hope im asking in the right section..
cheers
Andy
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Littlejohn
- OneWave
- Posts: 15
- Joined: Thu Nov 01, 2018 4:11 pm
Re: basic questions
Hello.
You are correct there will be no drop in the quality of the signal if connecting in the wiring as the signal needs to be good at the ecu. The down side is to seal the wires to prevent water intrusion afterwards. Making your own plugs is a good idea if you are testing the same type of sensors regularly.
You are correct there will be no drop in the quality of the signal if connecting in the wiring as the signal needs to be good at the ecu. The down side is to seal the wires to prevent water intrusion afterwards. Making your own plugs is a good idea if you are testing the same type of sensors regularly.
Re: basic questions
Thanks for that.. Its what I thought about the quality of signal.. I was just wondering about additional noise on the waveform which the ecu may well be able to filter.. I'll give it a go if I find any sensors awkward to access.. I'm thinking the crankshaft in particular..Littlejohn wrote: ↑Fri Aug 04, 2023 7:32 pmHello.
You are correct there will be no drop in the quality of the signal if connecting in the wiring as the signal needs to be good at the ecu. The down side is to seal the wires to prevent water intrusion afterwards. Making your own plugs is a good idea if you are testing the same type of sensors regularly.
Thanks again
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ben.martins
- Pico Staff Member
- Posts: 545
- Joined: Tue May 16, 2017 1:02 pm
Re: basic questions
Hi Andy,
Firstly, I must apologise for the late reply.
Thank you for raising this subject. I can imagine that some of the subjects on the forum can seem a little overwhelming for a new user. We do have a number of other resources available though that can help new users gain confidence in scope use.
Firstly it's worth taking a look at the training section on the website - https://www.picoauto.com/library/training. Here you will find some introductions to the software along with other articles to help get going with the Pico journey.
Secondly the guided tests within the software. Whilst the information is generic there is advice on how to connect, expected patterns as well as a 'Don't Panic' section should you need further support.
Thirdly there is the Pico App which is available on both Apple and Android. Search the app stores for Pico Automotive and you should find it. It is resource and training guide only but there is some useful introduction videos with this app that are aimed at new users and just in time learning.
Lastly, there is of course the forum. We are all from the industry and appreciate that we had to start somewhere. Everyone needs help from time to time and no-one can be expected to know everything so having the 19,000 users on this forum to ask for help from can only be a good thing. It's one thing I learnt quickly as a technician that the Pico community will help each other out, no matter what skill level. Please, if you have any questions and I mean any, just ask.
One thing I will mention is that whilst we don't offer direct training, there are a lot of people out there now that offer PicoScope training. In some cases our distributors will even offer training. It is well worth getting yourself on an introductory course to scope diagnosis as this will gain confidence in scope capturing and analysis.
I hope this helps.
Kind regards
Ben
Firstly, I must apologise for the late reply.
Thank you for raising this subject. I can imagine that some of the subjects on the forum can seem a little overwhelming for a new user. We do have a number of other resources available though that can help new users gain confidence in scope use.
Firstly it's worth taking a look at the training section on the website - https://www.picoauto.com/library/training. Here you will find some introductions to the software along with other articles to help get going with the Pico journey.
Secondly the guided tests within the software. Whilst the information is generic there is advice on how to connect, expected patterns as well as a 'Don't Panic' section should you need further support.
Thirdly there is the Pico App which is available on both Apple and Android. Search the app stores for Pico Automotive and you should find it. It is resource and training guide only but there is some useful introduction videos with this app that are aimed at new users and just in time learning.
Lastly, there is of course the forum. We are all from the industry and appreciate that we had to start somewhere. Everyone needs help from time to time and no-one can be expected to know everything so having the 19,000 users on this forum to ask for help from can only be a good thing. It's one thing I learnt quickly as a technician that the Pico community will help each other out, no matter what skill level. Please, if you have any questions and I mean any, just ask.
One thing I will mention is that whilst we don't offer direct training, there are a lot of people out there now that offer PicoScope training. In some cases our distributors will even offer training. It is well worth getting yourself on an introductory course to scope diagnosis as this will gain confidence in scope capturing and analysis.
I hope this helps.
Kind regards
Ben
Re: basic questions
Thanks Ben, and I take on board all your pointers.. I'm currently looking through the resources you mention, and have the app downloaded..
I actually did a course with pico way back when I first got the scope, but my issue will be the lack of regular use, it's a hobby to me and I don't have my own workshop/garage.. It all outdoor and back lanes when I can.. I'm sure you are getting the picture now lol...
None the less as I've said before I have a keen interest in vehicle maintenance and upkeep and I see a scope as part of that, so I keep trying..
Thanks again..
Andy.
I actually did a course with pico way back when I first got the scope, but my issue will be the lack of regular use, it's a hobby to me and I don't have my own workshop/garage.. It all outdoor and back lanes when I can.. I'm sure you are getting the picture now lol...
None the less as I've said before I have a keen interest in vehicle maintenance and upkeep and I see a scope as part of that, so I keep trying..
Thanks again..
Andy.
Re: basic questions
well I have had some success in my eyes anyhow..
over the last few days I have , with a little reading, help from the guided tests, and a little probing to help identify the correct signal wire, managed to get traces from the following sensors on a 2.2l landrover defender..
camshaft
crankshaft
manifold absolute pressure
air mass and temp
and fuel rail pressure..
the one that I had trouble with if thats the right term was the mass air flow... it is the digital type and I eventually identified the signal wire.. I followed the guided test and got similar traces to the examples shown in the guided test tutorial.... but the frequency trace on channel A has a large number of single line spikes that take it out of the 20kH scale range and I get a red flag warning that scale is over range, but other than that the trace is good and as expected..
I was also a little confused at the need for the frequency scaled channel ie channel A, and wondering how can voltage be related to frequency...if the air mass is related not to the amplitude of the digital signal in channel B but its rate of switching then could the time base of that digital voltage not be altered so that the frequency of switching could be measured.. is the trace of channel A not just a pictorial of what ive just tried to describe... but I still don't understand how a voltage can be related to the switching frequency of the digital pulses..
final question for now is if I want to add the waveforms to the library is it a matter of clicking on the save and upload button?? I have used the save button and that does add them to a folder on my laptop only
thanks for any response
Andy
over the last few days I have , with a little reading, help from the guided tests, and a little probing to help identify the correct signal wire, managed to get traces from the following sensors on a 2.2l landrover defender..
camshaft
crankshaft
manifold absolute pressure
air mass and temp
and fuel rail pressure..
the one that I had trouble with if thats the right term was the mass air flow... it is the digital type and I eventually identified the signal wire.. I followed the guided test and got similar traces to the examples shown in the guided test tutorial.... but the frequency trace on channel A has a large number of single line spikes that take it out of the 20kH scale range and I get a red flag warning that scale is over range, but other than that the trace is good and as expected..
I was also a little confused at the need for the frequency scaled channel ie channel A, and wondering how can voltage be related to frequency...if the air mass is related not to the amplitude of the digital signal in channel B but its rate of switching then could the time base of that digital voltage not be altered so that the frequency of switching could be measured.. is the trace of channel A not just a pictorial of what ive just tried to describe... but I still don't understand how a voltage can be related to the switching frequency of the digital pulses..
final question for now is if I want to add the waveforms to the library is it a matter of clicking on the save and upload button?? I have used the save button and that does add them to a folder on my laptop only
thanks for any response
Andy
Re: basic questions
Not sure if anyone can offer suggestions on this..
I have an engine coolant temp and air intake temp sensor I was trying to connect to... Led to believe they are both negative coefficient temp sensors that should receive a 5v supply..
When trying to probe them and add a set of breakout leads I was getting a 35v reading on either wire on the channel voltage scale.. Obviously wrong but got it on both sensors..
At the same time the dash instruments started misbehaving with full scale deflection on the coolant temp gauge.. The rev counter not working battery light on and the stability control light..
They eventually all cleared and a scan of fault codes produced some can high faults which I cleared and all is now well.. I haven't been back to the two sensors I was trying to get a trace from..
I have an engine coolant temp and air intake temp sensor I was trying to connect to... Led to believe they are both negative coefficient temp sensors that should receive a 5v supply..
When trying to probe them and add a set of breakout leads I was getting a 35v reading on either wire on the channel voltage scale.. Obviously wrong but got it on both sensors..
At the same time the dash instruments started misbehaving with full scale deflection on the coolant temp gauge.. The rev counter not working battery light on and the stability control light..
They eventually all cleared and a scan of fault codes produced some can high faults which I cleared and all is now well.. I haven't been back to the two sensors I was trying to get a trace from..
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Steve Smith
- Pico Staff Member
- Posts: 1594
- Joined: Sun Aug 25, 2013 7:22 am
Re: basic questions
Hello and thank you for the feedback
Great news you have commenced capture and used the Guided Tests to do so, thank you
Could you post your MAF meter waveform here and we can look at the results?
The over-range warning can be attributed to “noise” present on the signal and we may be able to combat this characteristic noise by using the PCM sensor ground at the MAF meter.
This can only be carried out if you are using a floating ground scope (4225, 4425, 4225A & 4425A)
We can also take advantage of the Bandwidth Limit feature (applicable to the scopes above) which will help remove high frequency noise above 20 kHz on channel A
The relationship between voltage and frequency is described in the Guided Test which I have highlighted above
What you describe, “wondering how can voltage be related to frequency...if the air mass is related not to the amplitude of the digital signal in channel B but its rate of switching then could the time base of that digital voltage not be altered so that the frequency of switching could be measured. is the trace of channel A not just a pictorial of what I’ve just tried to describe.” is correct in that channel A is graphing the frequency of the signal on channel B using the frequency counting feature of the scope, however it is plotting the frequency change against “Time”, our X axis
The beauty of retaining the X axis as “Time” means we can add other channels and correlate our graphed MAF to other signals over time such as, Crank and MAP
Changing the X axis to frequency can be done if required using the Instruments button and selecting “Spectrum” but this will become confusing when viewing multiple signals changing against time
The following links will help with frequency calculations:
https://www.picoauto.com/library/picosc ... y-counting
https://www.picoauto.com/library/traini ... duty-cycle
Moving onto uploading your waveform to the Reference Waveform Library (RWL) you will need to have your Automotive scope connected to your laptop and your laptop connected to the internet.
Fill out the relevant vehicle details required for a successful upload to the RWL and click on Save & Upload.
Below I have followed this process where I am now prompted to enter my User name and Password for the RWL
Once entered your waveform will be uploaded
More information on the RWL and Waveform manager can be found here in Ben’s video https://youtu.be/Pes4FtItMms
I hope this helps, take care.....Steve
Great news you have commenced capture and used the Guided Tests to do so, thank you
Could you post your MAF meter waveform here and we can look at the results?
The over-range warning can be attributed to “noise” present on the signal and we may be able to combat this characteristic noise by using the PCM sensor ground at the MAF meter.
This can only be carried out if you are using a floating ground scope (4225, 4425, 4225A & 4425A)
We can also take advantage of the Bandwidth Limit feature (applicable to the scopes above) which will help remove high frequency noise above 20 kHz on channel A
- Image 1
What you describe, “wondering how can voltage be related to frequency...if the air mass is related not to the amplitude of the digital signal in channel B but its rate of switching then could the time base of that digital voltage not be altered so that the frequency of switching could be measured. is the trace of channel A not just a pictorial of what I’ve just tried to describe.” is correct in that channel A is graphing the frequency of the signal on channel B using the frequency counting feature of the scope, however it is plotting the frequency change against “Time”, our X axis
The beauty of retaining the X axis as “Time” means we can add other channels and correlate our graphed MAF to other signals over time such as, Crank and MAP
Changing the X axis to frequency can be done if required using the Instruments button and selecting “Spectrum” but this will become confusing when viewing multiple signals changing against time
The following links will help with frequency calculations:
https://www.picoauto.com/library/picosc ... y-counting
https://www.picoauto.com/library/traini ... duty-cycle
Moving onto uploading your waveform to the Reference Waveform Library (RWL) you will need to have your Automotive scope connected to your laptop and your laptop connected to the internet.
Fill out the relevant vehicle details required for a successful upload to the RWL and click on Save & Upload.
Below I have followed this process where I am now prompted to enter my User name and Password for the RWL
- Image 2
More information on the RWL and Waveform manager can be found here in Ben’s video https://youtu.be/Pes4FtItMms
I hope this helps, take care.....Steve
Re: basic questions
thanks for the reply steve...unfortunately my scope isnt one of the models you suggest..its a 2 channel 4223.
if i could explain my confusion about the frequency scale on the voltage axis..
given a scope measures voltage against time and i understand how you can relate voltage to current measurement and scale the axis in amps, i was struggling to see how you could scale it in hertz, as i couldnt see how voltage could be related to frequency...
i did grasp that the air mass was related to the frequency of switching of the digital voltage..
im not sure how else to explain my confusion ...
i am hoping to upload some known good waveforms to the waveform library, in the next few weeks..ill check out your links, and ill try and attach some captures of the mass air flow traces i was on about in the earlier post to this reply..
thanks again
if i could explain my confusion about the frequency scale on the voltage axis..
given a scope measures voltage against time and i understand how you can relate voltage to current measurement and scale the axis in amps, i was struggling to see how you could scale it in hertz, as i couldnt see how voltage could be related to frequency...
i did grasp that the air mass was related to the frequency of switching of the digital voltage..
im not sure how else to explain my confusion ...
i am hoping to upload some known good waveforms to the waveform library, in the next few weeks..ill check out your links, and ill try and attach some captures of the mass air flow traces i was on about in the earlier post to this reply..
thanks again
Re: basic questions
looks like someone will have to give me a pointer on how to add the scope captures ive saved to my laptop to a post on the forum...thought id managed to do it but it but it seems not 