Starter problems

I just recently finished over hauling my 20R for my 1980 Yota we got the engine in place and bolted up, and I replaced the solenoid contacts in the starter put it all back together, and placed it in the truck I got the wires all hooked up and when I got to the ground cable to the battery it started to turn over by itself? So is the problem inside at the contacts or did I not put it back together right?

I found the problem