door switch / dome lamps

[paintinx]

Hej,

I am currently trying to repair the dome lights at my 79suburban.

Right now there are now light and also no voltage in the socket.

My way was:

I have found these little switch in the driver door frame.
is this the "ground"switch for the dome light?
does it work like a "breaker"?

i asume that I have to switch the (car) lights on and the
knob should be in the left / fixed position, right?

next: i have checked all fuses - but maybe - the fuse isnt there (under the
dashboard) - how is the fuse called???

(cigarette lighter is the same fuse as the HORN)

would be great to get some tipps

thx in advance, stephan

ps: i know the thread "http://67-72chevytrucks.com/vboard/showthread.php?t=481653"