To answer, the position itself won’t change if it’s in-phase or not – the wiring does. Think reverse polarity or reversing the ground and hot wires. If we reverse the current flow on one pickup only, and two are selected, one will be out-of-phase from the other. The results of this are usually major bands of frequency cancelling each other out- creating a thin and nasally tone. But when just one pickup is selected, it sounds normal and full range.
Learn tips like this and more at our Wiring Class Feb.1 in Edmonton and May 24 in Calgary.