Courtesy light / dome light wiring

If its any help, on North American A-bodies, the dome light gets power from the same fuse as other 'altways hot' lights.
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The actual location of the junction varies.
1967 (except maybe fastbacks and 'verts) it was done at the headlight switch
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Yellow is the earth side going to the on/off switches - one in each door jamb and one in the headlight switch.