Tested Gauge Clusters

[BillsGU]

The first couple of times I hooked up the oscilloscope the square wave was about 1.5 -2.0 volts at the top of nine volts dc. That is why I said a 9v bias. Today my scope shows a square wave as just a 7-8 volt wave (peak to peak) to earth. I have no idea why it has done this as I haven't changed the parameters. I am still struggling to understand the chinese instruction manual.

Edit: Maybe early on, I measured just across the resistor and not from the yellow black to earth??

OK - the second reading makes more sense. You can't use a (normal 240 volt) scope like you use a multi meter. You can't just poke it into a circuit and measure across components because the negative clip is earth. All of your measurements must be wrt earth.