[theduke]

I've not seen those thermisters in a 855/955.

As to safety's

2 under the seat.....one is a switch which I believe is for pto the other is a rod with a plastic screw on tip that sort of locks the go pedals when not in the seat.

Do you have the manual?

There are several different wiring diagrams in the manual.
Yours should be a late model 855....most similar to the 955.
Manual covers 6 models and is not super clear on what is what in many areas.

 

[theduke]

That is correct
There are only 2 small"brain" type box's on these tractors.
1 is something to do with the glow plugs. I forget what the other one does.
Might check the fuse area for a loose connection or the nut on top of starter where everything is powered from.