1994 Ford Escort wont crank

This escort I am looking at would just click. I checked the voltage and had 12.85. Noticed some corrosion on the posiitve cable. When I went to remove the clamp it started cranking by itself. Now when I turn the key I get just a click on the passenger side fiirewall. I checked the voltage to the starter ok. And the solonoid was weak voltage. I removed the cooling fan relay and jumped the two of the four connectors and it would crank. And with the key on it will start. But not from the switch. But when you turn the switch to start you still hear relays click? Any answers dont know where the neutral saftey switch is at