Viewing Power and Ground signal's
I think one of a labscope's best feature's is allowing voltage signals to be recorded over a period of time. Power and ground circuits can be watched by the scope looking for any change on either one, or even both at the same time. Let's say you have one of the infamous digital instrument cluster's that winks on and off. Maybe the cluster is losing the ground... or maybe its losing power... It may not be easy to hookup to one and plot the signal's to see if they go away, but this would be one way of finding out. Then you would be sure its the cluster that needs repair. How about multiple onboard computer's that need to communicate with each other over serial data lines? Or again, digital instrument clusters that receive that same serial data. If you can tap into these lines, you can check them to see if they are sending this data and plot them to see if they are consistent. Below are some sample images.
Voltage drop plot.