Wiring turn signal brake lights

Ground your multimeter, turn on your hazards and stick the positive probe into each of the wires heading into that first junction box that your new turn signal switch plugs into and see if you get fluctuating charge from all of them at that point. If not you have a ground inside the column and your new switch.

PS if your fusible link is hotter than 25amps you may want to tune that down until you've fixed the problem.