It's charging because the alternator is being revved enough to self-excite, hence the WL illuminating.
The reason it does so is because there is a potential difference (not being an old Ford).
That is to say, two lives extinguish the light. As you have no power to it, what it happening is only one side (from the alternator) has power and the other is a ground. This is the exact reverse of the indication of no charge when working correctly.
The fuel gauge is not conventional (i.e. when switched off the gauge does not drop) and the illumination/panel lights power is from the lighting circuit, so as I say the issue is no power.
Martin