Well I can't read schematics but it won't cause any liability if you tell me my guess 2 posts above is wrong. You don't have to tell me its right.

Well it looks like the contacts on the seat switch are closed until you sit on the seat and then they open.

If it's in your way pull the trans release on the back of the hitch and push or pull it.

I think you are correct.

I know nothing about a 2166, but my 2180 seat switch is closed until I sit on it.
Frankly, it is opposite the logic I expected, but that is what I found.

To bypass it, all I need to do is unplug it. No jumper needed.

Yeah its hard to pull a tractor and trailer by hand though. I need to get it running https://www.onlycubcadets.net/forum/...ad.php?t=60620

Do you think the seat switch and starting issue are related? Just a thought.

No I don't think so. I'm 99.999% sure the seat switch is not involved.

Do you know where I can find a legible copy of this diagram?

I sent it to your e-mail.

Thanks! I was puzzling over the 6th terminal on my ignition which is not part of the harness plug and it appears to be for the headlights