SRT
I've had my meter on both ends, one end is the connector you're talking about and the other end is the turn signal switch.
70hemi GTX
Nothing personal but i've tested the wiring right up to the switch and it's the wiring in the column.
I've swapped the bulbs side for side changed the one on that side, sprayed wd40 into the holders check the ground wires and cleaned them, also added an extra ground to the dash frame.
If i swap to the green wire on the connector under the dash, which feeds the other turn signal it works.
How can it be a bad ground ?