That description I wrote only applies specifically to the older cars with the separate, dash mount hazard switch. But the idea is the same. Without sitting down with one and going through it, I could not diagram it. In the old days I fixed mine and a couple other guys where the hazard switch failed and kept the stop lights from working. I just moved a wirein there and re-soldered it, then cut the knob off the hazard switch so it could not be activated, LOL
I would guess in your case., that some contacts are improperly "floating around" in the switch.