My first post in this Forum
I live in Norway, and own a John Deere 6820, that i have an issue with the PTO RPM display/selection.

The tractor is an John Deere B7, 2005. With chassi number L06820N444568, and powerquad transmission

When i use the PTO gear lever, set to 540rpm - everything works fine - The BIF display show's the RPM, and correctly warns about high RPM if my engine RPM gets too high. (About 620 rpm)

But when i change the PTO gear lever to 1000 RPM, i get a warning message in the BIF display at around 620 RPM that "PTO RPM is too high, reduce engine speed"

So my question is - What tells the computer (BIF) that i have selected 1000RPM on the gear lever, and not 540 ? Is there a switch, or an inductive giver somewhere linked to the lever ?
My local service guy is claiming that the only giver is the RPM sensor itself, and that there is no other sensors/givers on this system..

I cannot see how this is possible, something must be changing state, because i have had 1000RPM readings in the BIF earlier, when 1000RPM was chosen on the gear lever...

I have checked directly beneath the lever cover on the lever - but it only disappears into the abyss, without any givers...