[RustyPile]

Every electron that's moving with the ignition switch activated -- The power for every item that functions only when the ignition switch is on passes through the ignition switch.. Ignition system, turn signals, radio, heater/AC system, etc. are only some of those items.. That's a lot of current.. Over time, wear takes place, connections become loose, corrosion builds up.. All are contributors to the cause of resistance.. A byproduct of this resistance is heat.. The melted plug at the ignition switch is evidence of that heat.. It melted not because of a single component failure but the failure of several items.. It's a good bet the starter is a victim, not the cause, of this damage.

You keep insisting on replacing the starter.. Randomly throwing parts at a problem is the least effective and most expensive approach to a solution. Use good diagnostic procedures in solving the various issues.. You've got lots of wiring problems to diagnose and repair long before you can determine if the present starter, or a new one, functions properly.

That plug along with pigtail wires is available.. The red wire is part of the main power distribution wiring. It originates at the battery and has voltage on it all the time (hot). The pink wire feeds power from the switch to the fuse box. It's hot only when the ignition switch is on. The purple wire carries power to the starter solenoid only in the start position.. It doesn't go from the switch directly to the solenoid.. It goes first to either a neutral safety switch (for an automatic transmission) or a clutch safety switch (for a manual transmission), then to the solenoid. There are other wires in that plug.. The first step is making sure all fusible links are in good operating condition.. There are no fuses in the main power distribution system, only these fusible links. Refer to a proper wiring diagram when doing any electrical repairs.