Jan 16, 2017 - 06:36 AM
The ground lead of the AES Primary AES# 01-18-Snap is not attenuated. It provides a non-resisted path for the ground connection.
Many of these types of diesel injector circuits are both switch to ground and switch to power. There are many ways to connect for testing. To help solve this issue, it would be helpful to have a diagram of the circuit and the desired instrument connection points with a description of the purpose.
Here are some notes based on the wording used in your question:
"...stacking grounds…” implies that the ground connections for each channel will be at the same point in the circuit/system. If this is the case, then isolated channels or not, the channels will be tied together via the ground. On a scope that does not have isolated channels, you only need to make one ground connection to the system and all instrument channels are ready for signal connection/testing.
An option:Some diesel injectors can have some pretty wild and complex voltage waveforms. Consider using a low amp probe to analyze how much energy is passing through the circuit and how the energy is being used. A current waveform will be very concise.
Jan 18, 2017 - 10:18 AM
If using a common channel ground oscilloscope, I imagine the following should give you the info you are looking for:
Put a scope on a good chassis, engine, or battery ground.
Put channel 1 on the wire between the ground switch and the injector and do the same for channel 2 on the pump valve.
If the signal is not giving you what you want, move to the wire that goes between the load and the switch to power.
Keep in mind that both circuits have a common ground.
They might not have a common power since one circuit might be 80 volts for example and the other not.
Hope this helps.Jorge