The voltage transformer thing was fitted to rovers over here around the 1990's.
What it did was... if you selected "dipped beam", that is, full headlights, with the igniton on, then you got full lights.
If you turn the ignition/engine off, the headlights go out, but the small sidelight/marker lights stay on.
There was a rule in the UK road laws that said you couldn't drive with such small marker lights on, so as such, if you try having just "side" lights on with the ignition, the voltage transformer gave 1/10 voltage to the headlights, giving them that dull glow. there should be a large wire wound resistor bolted up in the RH (i think) fender which does the voltage reduction, and a relay up under the dash to control all of this shenanigans.
you can just pull the relay out and be done with it, so reverting back to main, side or off. (later rovers don't have this, as the rules changed)