Why your meter shows 12 volts at the square connector.
12 volts positive is going thru the bullet connector, and continues thru the bulb to the square connector. That's why if you put a ground to the square connector the bulb lights. If you took the bulb out, it would now show 0 voltage at the square connector. ( the path of electricity was broken by removing the bulb.)
This is correct, right John?
1957 WILLYS pickup,
1973 J 4000,
1978 CJ7 DD.
1979 CJ7 360, TH400/Quadratrac.
1980 CJ5 trail Jeep.
1989 YJ the CJ to YJ.