Dan… I’ve got a JD 320 skid steer. Starts and only runs for…

F9D5 - Coolant temp input high. This is either for overheating or a false overheating code due to a faulty sensor or wiring harness in that coolant temp circuit. Check for both. Be sure to check all of your fuses and relays as well as your wiring harness and connector pins for any corrosion or damage. It's a pleasure to help anyway I can.

There is no master reset code. It is possible that this is shutting down thinking that it's overheating. You will want to see if power is being removed from the fuel shutoff solenoid indicating that the controller is commanding the engine to shut down. If there is still power to the fuel shut off but the machine is stalling out and dying, that is more of an indication that there could be an excessive load on the engine such as a hydraulic system problem or a potential fuel system issue within the injection pump, etc. check for power and proper operation of the fuel shutoff. Also check from metal or debris within the hydraulic filter which would look like glitter in the oil and filter if present. This could indicate a hydraulic component problem that is keeping the engine under too much of a load.

That is correct. Now if by any chance a cable or something came in contact creating an arc when connecting the batteries or if there was any kind of spark, etc. it could have caused a problem with the computer software and controller.

If there is a software related glitch, only the dealer can connect to it with John Deere service advisor to reflash and reprogram the software to set it back to factory settings.

The two ways to check the computer is to plug into it with a laptop and service advisor to see if you can communicate with it, also verify power and ground to it to be sure that it is powering up, and in some cases at the dealer to swap it out with a known good one from another machine for testing purposes. Some dealerships have the ability to test yours on the bench. You can call your dealer and asked them if they have the ability to check it if you were to remove it and bring it to them.

Not without the use of a shop crane or other piece of equipment to support and lift the loader arms while disconnecting the cylinder hoses and slowly lifting it in position to install the boom lock. If there are lock valves in the circuit, you will need to remove the cartridges from the lock valves so the cylinders will move.

Pleasure to help.

I would check to see if power is being removed from it causing it to shut down or if it is a weak solenoid in need of replacement that is kicking out even with power still there.