Ever since the signals to be tested are emitted from simple on/off operations, the ocilloscope has been interesting for the area of diagnosis in the field of vehicle engines. Nowadays it is a component of almost every tester, it also often has a built-in scanner.
What happens is, is that through an electric contact to a certain wire, a signal is picked up and shown on the screen, this is caused by a tension change in certain short intervals. This can be, in the case of the scanner, also a computer monitor.
The latter offers fairly reasonably priced oscilloscope functions. It is even cheaper, if the computer picks up the signal directly, by way of a suitable interface, and then does the evaluation itself. Admittedly, one cannot expect a particularly high sampling-rate. The data-block of a CAN-bus can probably only be analysed with increased computer performance.
Let's turn to the microscopes which are seperate from the computers. We have long left the age of analogue devices which could not store data. In most monitors the display is also in pixel form. As far as prices are concerned, e.g., for sophisticated laboratory devices, the sky's the limit. That being said, a high performance oscilloscope can also be had for a four-figure sum.
This of course, is not the case in the workshops, where employees with varying qualifications require particularly user-friendly devices, they can cost a good deal more than €1000. For those who are familiar with oscilloscopes, these influences can be sometimes be an impediment and they would prefer, for the higher price, more performance.
Fact is, that the devices can often obstinately influence the signals. Because, with the oscilloscope, depending on the setting changes, one has to constantly make adjustments, any additional influence triggered by the device itself is often obstructive. Apart from that, there are of course, far fewer setting options and this distinctly alters the signals which are being switched to-and-fro.
The multitude of different channels are connected internally, which is why, quite often, only one earth connection is sufficient. The forwarding of these channels to the earth-contact can be a problem, this is described in mains voltage01. The problem does not appear directly on the vehicle and you will probably not want to explore the mains voltage with an oscilloscope.
One should also leave the high-voltage batteries of modern electro-mobiles and hybrids alone, particularly because an additional qualification is required, even to decommision them. However, if you have, for the purpose of demonstration, connected various components, of course using an adapter and not the car-battery, you may well ask yourself if the stubborn short-circuiting problem is perhaps caused by the earthing-/safety-ground connection.
Measurments can be made on the car directly (via the tester), or indirectly (reading out the control device). In the first case, one of the newer hand-held devices can sometimes be recommended. This is described under the keyword multimeter, because the hand-helds are a combination of both. This can also be read out when the vehicle is in operation, indeed, not by the driver.
If, for some reason, one has to do without a passenger, the individual signals can also be stored. In smaller devices with a lower screen resolution, this has the additional advantage that one can zoom the rendition, thus stretching it, thereby making the sampling rate of the device more useful. Of course, all this is also possible using a laptop and also using scopes between the measuring point and the laptop. In some cases one can even leave the laptop at home.