The idea of this thread is to get a list of useful tips together for all users of PicoScope Automotive.
We would like to encourage every forum member to have a go at adding to the list. Something you may find logical may not occur to others.
A couple of items to note:
If you do not believe a tip to be worthwhile please do not voice that opinion here.
Every tip will be useful to someone.
If you have an alternative method to a tip already mentioned, please quote the initial tip when detailing your method.
Keep the tips relatively short.
Screenshots are allowed if required.
So, to get started:
1. If unsure of the time base you should be using, choose 20 ms/div. This gives 200 ms across the screen which is enough for a complete engine cycle (2 revolutions) at idle. The 20/20 rule is a great starting point, 20 ms/div and ±20 V range.
2. When measuring voltage try to test the component and its wiring. This means that for sensors you should measure near to the ECU and for actuators at the component itself.
3) When measuring current remember that the current flowing is the same throughout a circuit so you can pick a point where it is easy to measure. This can vary from vehicle to vehicle - for example if measuring starter current then on some vehicles its easy to get to the starter and on others its easier to get to the battery.
When measuring actuators such as injectors and ignition coils then study the wiring diagram, there is often a fuse, relay or junction where you can measure the current drawn by all the injectors / ignition coils at once.
Here's a tip to make up number 4)
The ALARM feature of Picoscope can be used to emit a BEEP or a sound of your choice (.wav file) when your waveform meets a pre-set criteria. For example problem vehicles often run fine with the test equipment attached. With your scope you set a trigger to capture these intermittent faults as they happen, and then sound an internal PC speaker or even external speakers playing a tune of your choice. This allows you to walk away from your scope and continue with other duties safe in the knowledge the scope is waiting for your fault to occur and will let you know via the speakers.Click on TOOLS-ALARMS and tick the CAPTURE box and enjoy.
5) To save an image on screen as a ghost: (Reference waveform)
First capture trace or open a previously saved trace and freeze screen
Select tool, reference waveforms, duplicate, tick the box, then OK.
When running the scope after the above, the scope trace will always be present under the current waveform running on screen.See the image attached.
Not sure it comes under "Top Tips", however, a mistake not to make;
When 'scoping ABS sensors at the controller, it is tempting to determine which circuit is which by turning each wheel by hand (vehicle suspended in the air), as many manufacturers use common wire colours for each corner of the car. This is a bad idea! Gently rock each wheel very slightly, to determine which circuit it is connected-to.
Why?
Because if you have two or more wheels connected by transmission differentials, a forward rotation on one wheel will result in a reverse rotation on another, if the central transmission drag is high enough to stall the differential input flange. An ABS sensor will not show wheel rotational direction in the signal. Slight rocking of the wheel will move the ABS reluctor ring relative to the sensor nose, but will not move other wheels within the backlash of the differential.
Remember when using your Picoscope you can link your computer to a widescreen monitor allowing you to see the scope trace easily from afar which can be a god send when working alone, E.g. cranking a vehicle whilst monitoring the scope trace. Using a wireless keyboard with integrated mouse can then give the ability to control your PicoScope via a widescreen monitor from inside the vehicle whilst increasing engine temperature, engine speed, etc.
When viewing waveforms from 2 different channels, there may be times when it is difficult to see the relationship between waveforms where they clash on screen. Click 1 SCALE OFFSET-Click 2 SEND WAVEFORM TO THE BACK- Click 3 BRING WAVEFORM TO THE FRONT. Now you can see all the signals at all times