Technical Mk1 Interior light and Map Light

[dukeboys]

My interior light works when the doors are opened however with the doors closed and the light switch moved from the AUTO to the ON position i get nothing.
the map light doesnt work either.
the fuses are all ok
map light buld is ok and the bulb for the courtesy light is obviously OK just cant suss out why its not working correctly.
I dont believe there are any relays for this light.
is there a way to test the switch in its ON position for power?

wondering if the the slider switch is knackered inside or could there be a fault with the door switches causing an issue?
i tried another interior lighting assembly and the same thing happens suggesting a broken wire or something else.....
had a bit of welding done recently and its almost like ive had this issue since then so wonder if the welder has created this issue by causing a short of some description .......

 

[AnteLo]

There is probably a burned fuse somewhere

 

[Frank Folker]

There are 3 wires for those lights in there, I don't remember in which order but it's pretty easy to figure out once you take the housing off. They are getting constant +12V (one wire) and switches regulate connection to negative (0V). "Auto" setting lets the bulb ground through door switch (2nd wire) and "on" setting completes the circuit to a regular constant 0V (3rd wire). If the dome light is working in "auto" with door open, but neither light works in "on" position, that indicates you lost the constant 0V, either a broken wire or a corroded contact somewhere. You can investigate where the issue is and fix properly or just bypass it and make a connection somewhere to roof metal (close to the light).

 

[Mike1alike]

I have a similar issue with the light, it works sith open doors, but not with them closed. I noticed this recently, didn't get to it yet, I will do that.
One other thing, and this is probably why I didn't get to it, is that after I get the light on, with the door opened, I close the door and press the switch and sooner or later the light comes on. So I suspect it's an oxidized wire that needs to be cleaned. I will do that. The wire plug contact could be the exact spot that needs cleaning and if so, at yours that is why the light doesn't work even with a different light assembley.