Strange radio wiring. This is just for interest, am not trying to fix
anything (for a change)!

An ancient Nissan Micra K11 radio - wiring to the radio has these
wires for power.

2 wires. (The rest all seem to be for the speakers)
a) is +12Vdc all the time
b) is +12 Vdc when the ign key is set to Aux.

Start Engine

Same readings as above *except*, if turn any of the lights on (parking
lights, main beams), power to both cables goes off! That would turn
the radio off at night : No?