you need to pull one wire at a time and see if the trouble goes away. What you are trying to do, here, is narrow things down. So itemize what you removed, one at a time, "does it stop" the starter?
Here's how this works.........
Your starter solenoid.........down on / in the starter........has a big main battery wire, and the small solenoid wire. If you apply power to the small terminal, the solenoid pulls in and operates the starter.
THAT SOLENOID draws a LOT of current, so ma used a firewall mounted relay for TWO reasons.......it removes load from the ignition switch, and gives a method to operate the neutral safety switch.
The two 'push on' terminals on the relay are the relay COIL (electromagnet) They are electrically interchangeable. One of them goes down the firewall, to the transmission neutral safety switch and connects to the MIDDLE terminal of the NSS. The NSS is GROUNDED in park or neutral, thus providing a ground for the relay coil
The remaining "push on" terminal hooks to your yellow start wire which comes from the ignition switch. Twist the key, the yellow engages the relay.
The largest stud on the relay is 1/2 of the relay contacts AND is a battery junction point. That IS battery power
When the NSS is grounded, and you twist the key, the relay engages, jumpering the big batt stud to the "square" screw terminal. THAT then feeds battery power down to the starter solenoid.
