John deere x475 pto won't engage - Craftsman 42 in. Deck 19.5hp Lawn Tractor

I don't know but I would guess it could be for a differential lock or to engage the PTO (power take-off).

Try the following test. For safety purposes remove spark plugs. Now with engine off and key in run position turn PTO on. You should hear the clutch engage (clunk). Grab both sides of the clutch pulley and try to rotate the pulley. If the clutch is properly engaged you will not be able to rotate the clutch pulley without turning the engine.

PTO most likely

To remove broken key use an o ring pick and a doctors stitch twizzers . works every time.

These John Deere Garden Tractors have a RIO (Reverse Implement Option) on the PTO. If your PTO is engaged and you back up, the PTO will automatically stop. To reset it, depress your PTO engagement switch to the OFF position. Take your foot off the reverse pedal. Pull up on the PTO engagement switch. The PTO should restart. To use the RIO feature, pull up on the PTO switch for a second or two just before you step on the reverse hydrostatic pedal. The yellow RIO indicator light should come on your dashboard and you can now back up with the PTO still running. Works great for snow blowing when I don't want to keep resetting my electric PTO clutch to keep restarting my snow blower.

If your PTO will not restart, you may have a PTO switch starting to fail, or a likely logic problem in your electric PTO control module, or one of your forward/reverse indicator switches, which is linked to your PTO control module along with the overtemp circuit, is stuck/faulty.

look at the fuses there maybe a blown one

check for power at the clutch if no power check the safety switches and the switch itself

Park brake switch is the most likely culprit,any other would cause the tractor to not turn over in the crank position.

Check fuses.Does the dash light for PTO come on?Right side screen by pedals sometimes comes in contact with wires and cuts them.This happens mainly on the older units.

The PTO usually has a clutch that has to be engaged so that you can select the PTO rotation setting. I had a problem like that on my tractor and all it needed was a little adjustment on the PTO clutch lever, so it could disengage the PTO gearbox properly.