Dome light stays on all the time
could be.
If you pull the connector from the back of the light switch and have all the doors closed there should be infinite ohms ( ie open cir) to ground on the equivalent of M2 on the dome light wiring
(i'm going out on a limb here assuming the 74 and 67 wiring is mostly the same)
If the wiring is the same all that is needed to make the dome lights stay on is a short to ground in one of the wires going to the door switches, a damaged door switch, or the headlight switch is defective.
if you disconnect the door switch wiring and the headlight switch connector you should have an open cir to ground in the door switch wire if it is 0 ohms ( ie shorted) there is something else making the ground.
I seem to recall that some cars had a timer relay that would keep the dome lights on for a few seconds after the doors were shut.
