Welcome to MTF! Lots of info here and great members to help and share with, enjoy the site! Here is some site navigation assistance in case you need it. I've moved your thread to the Zero Turn forum to get responses.

Maybe figure out what those error codes are? Might be listed in the operators manual...

Edit:
And it is highly unlikely that the starter solenoid itself is the problem. While it could be a poor connection on (ie, corrosion on the connectors and/or post), the solenoid itself is only used for the brief period when the starter is activated.

Excessive current through PTO switch. Which could explain the pto shutting off. But would that problem cause a complete power failure? And I don't believe the Solenoid itself is the issue, but removing the small block fuse that goes to the solenoid is the only temporary quick fix I've found. Could that fuse reset something? Two different John Deere service centers have been unable to resolve it.

dave_r said:

Maybe figure out what those error codes are? Might be listed in the operators manual...

Edit:
And it is highly unlikely that the starter solenoid itself is the problem. While it could be a poor connection on (ie, corrosion on the connectors and/or post), the solenoid itself is only used for the brief period when the starter is activated.

Click to expand...

That's not something I would think JD would have a computer track...but if that's what the error code means, then I would start with:
-examining the wiring harness for the pto circuit for any spots where the insulation has been worn through
-put a inline ammeter in the pto circuit, where you can what how it changes over time.

Perhaps there's some heat-related issue with the pto clutch, so when it gets hot it uses more current. And maybe it gets to the point where it drops the overall voltage too low, but it's not enough to blow the fuse (depending on where the fuse is, maybe it can draw too much from the engine charging circuit, which may not go through that fuse...