Ok, I have tried for a whole day and failed. The interior electrics on my 420G have me foxed. Here are the symptoms:
When inserting a fuse in fuse holder 7, all interior lights come on, despite doors being closed. Door switches in the front I could undo and check and they are OK, the rear ones are in the door hinge screws and I can’t undo those to check them
The interior light (dim) switch does switch on in position one, but in position two blows the fuse (no 7). The purple/yellow wire at the rear of the switch was disconnected to prevent this from happening.
The instrument lights do not work at all, despite headlights all working fine and all the remaining fuses being fine. Nor do the ignition and headlamps lights inside the speedo work… suspect same root cause, but can’t be sure.
Rear reading lights do not work, bulbs and switches are fine, just no 12V feed.
I have tried looking at the wiring diagram, but can’t see where wires may be crossed over/unplugged… I suspect there is a 'grounding somewhere, but I don’t know where to start.