I have a Syncro Start Solenoid I am trying to troubleshoot on my generator. It has 3 terminals, a Pos +, a Neg -, and a Aux. What is this Aux terminal for? If I put power to it, it will pull the rod back just the Pos connection point, but the Pos point will work with a 10 amp fuse, when I do the Aux terminal it blows, 10, and 15 amp fuses and comes close to blowing a 20. What is this terminal for?

 

There are many variations of the syncro-start arrangement and it's been awhile since I looked at a schematic, but I would take a guess and you can check it out.
As I remember the power requirement(amps)to pull in the plunger is a lot higher than to hold it in once it's there.When the plunger bottoms out it hits a contact that de-energizes the pull in windings so the amp load drops.I have seen this aux post used to energize something else when the plunger bottoms.One thing I remember is if the adjustment doesn't allow the plunger to switch off the pull in windings she will go up in smoke--shortly but not immediately.

 

Ok I check on their website and see what I come with, thank you!

 

That is correct - on some solenoids, actuators etc. there are two sets of windings: one to move the load ("pull-in" or "open"), and another to hold in that position or state... sounds like the plunger is not reaching full travel or switching to the hold windings.