Well it is not that simple. I wish it was. Switch have different internal configs depending which one it is. Got any numbers on the switch and possible manufacture? I only seen a handful of hardwired switches but never had a problem with them so never got into finding info on them.
These GT20 riders where made from 88 to 95.
Also if the GT20 has the six digit model number it might help in the research if you post it; otherwise, it is an educated guessing game.