Oil Quantity Indicator

Ok.. I got two Engine Oil Quantity Indicators and this is the way to find them:

Brand: Simmonds Precision
PN: 10031-0000-01
Boeing PN: 10-60722-8

This how this part looks like:

This unit works with a power supply of 115V 400Hz and I believe that it is measuring the level of oil using the capacitance method, I'm really not sure at this point.

Let see inside:

As we can see it is a pure analog device.

After doing back engineering I could discover this pinout:

Again I don't have a picture of the oscilloscope when I tested this, but the pins 2 and 3 are 400Hz sinusoidal outputs.

The pin 3 provides a sine wave where the amplitude is proportional to the position of the pointer.

This signal is compared outside of the instrument with the signal provided by the pin 2, which is a fixed amplitude sine wave.

I will upload some videos of the system working.