Loss/intermittant IP/console lights on '83 Mondial QV

Problem 1:
IP/console lights come on with the light switch, but turn off after a few seconds. Repeatable. While driving, the IP/console lights come on and go off, then after a while, stay on. The "lights on" light in the IP, and the exterior lights all work correctly, as do the instruments that are grounded on the same wire.
Problem 2:
The official wiring diagram does not show the power supply to the IP/console lights, only its distribution. I was unable to trace the supply line inside the car.
Fix:
Bridge between the working power supply of the "lights on" light and the faulty supply line to the IP/console lights. I know this doesn't solve the underlying problem, but...
Result:
IP/console lights work as required, and are as bright as you wish they'd be.

For those of you who may experience the same issue, following the diagram of the IP/console lights as found in the official book, drawn out to match the layout in the car so you can understand where what is. (RHD, sorry LHDers). The wire colors are correct, except: In green, what I THINK is the path of the power supply to the IP/console lights.
Again, no information on that part anywhere. If someone can enlighten me, pls do so.

Pratically: remove the speedo, remove the switch block, carefully pull out enough of the switch block's wires to be able to work on them. Find the pink and the yellow wire going to the rr fog switch, bridge them with a short wire and 2 of those V clips that allow to hook 1 new wire to an existing one without cutting it. 45' job. Do it at night, so you can enjoy the result!
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