Okay- so to suss this out further-
The trigger coil in the relay is, in actuality, an electromagnet. Feeding it power at both terminals energizes the electromagnet, pulling the high current contacts into place. Agreed so far? Great.
Now- it's a magnet. Magnets attract ferrous metals (the high current contact arm). When do magnets ever
repel? Only when directed at the same pole of another magnet. Agreed? Have you ever seen a single magnet
repel ferrous metal? I have not. So why would polarity matter on the relay coil terminals? Discuss...
(Sorry Raposak- but this might be important)
Actually you can do this without an additional relay, LOL. First get yourself a momentary push button switch, some assorted wire, and a starter solenoid that is NOT self grounding.
1. Splice wire into neutral indicator light wire.
2. Then connect that wire to the push button switch, and connect a second wire from the other terminal on the switch to one of the small terminals on the starter solenoid.
3. After that, route a second wire from the other small terminal on the solenoid to the positive battery terminal.
4. Next run a heavy wire from the battery's positive terminal to one of the large terminals on the solenoid.
5. Finally use another heavy gauge wire to go from the remaining large terminal on the solenoid to the positive terminal on the starter motor.
This working, would depend on whether the OP's starter has a built-in solenoid. In which case, it's cheaper and easier to go get a $2 relay.
