BK 18120, Wiring

[Serum]

i allready explained why it sparked.

that is the reason why you measure a voltage too

it IS a circuit you are measuring. it simple is a circuit, nothing els.

the internal resistance of the capacitors and all the other electroncs that make part of the speedo is much, much lower then the internal resistance of the voltmeter that is why you measure something on the place you are measuring.. but like i stated for the reason why you see the sparcs (allmost 0 Ohm for the capacitors when they are not charged)

Your statement '0 ohm only at full throttle' is wrong too. it is not loaded the way you measure it. It needs to be fed with the full set of batteries and giving a WOT, loaded with a motor, before you can measure the difference in internal resistance of the controller. (only then the fetts/transistors can make a difference in internal resistance.

You need some electronical background to understand what i am saying, but i can't explain it in another way.

Looking at your drawings, you don't know what you are doing (no wrong intention here!! Don't get me wrong) but the measurement you are doing makes no sence at all.