Witts's end!

[Harry in Ky]

I have a 1990 Ford 7710 series ll. I have replaced the alternator and battery still not charging. I noticed that the previous owner unplugged or did something to the safety switch. Could this be the reason the tractor is not charging? If not, what else can I look for.

What safety switch? Most charging systems don't have a safety switch. Is it a Motorola alternator with an external regulator? (little square tin box with a four wire harness plug)

Is there a battery temp sensor under the battery tray?