So this weekend we had a break in the rain (finally) and I got to look at the solenoid. Before I replaced it, I wanted to see if, when I pushed the switch to the MOM position, if I was getting full voltage across the solenoid.
So I disconnected the engine battery, and then I first measured voltage of the House batteries at the house post on the charging solenoid. It was like 12V. Then I had a helper hold MOM and I measured the voltage on the other side of the solenoid. It was the same.
So, the existing solenoid seems to be functioning fine.
So I went and had a look at the engine starting solenoid. And I discovered that the positive terminal nut was loose. Not flop-around loose, but I could pull on the battery cable lead and easily turn it on its post. So it's quite likely that I had a poor engine battery connection at the positive post of the engine start solenoid.
I pulled all the terminals off the post, wire brushed them, and put it all back together and snugged it down good and tight.
