EX120 Swing Motor Works Intermittently

Hi Everyone,
Here's a new one...
Classic breakdown procedure -> was working just fine over the weekend; parked and shutdown as usual.
Today -> After starting the machine the Swing motor stops working after a minute or two of operation. All other stick operations including drive track work properly.
Overarching issue is that after a moment or two (after starting the machine) an issue occurs where the swing motor stick Does Not bring the machine out of idle mode, nor does the swing motor rotate.

Discovery; If I let the machine warm up for 20+ minutes, everything seems to work properly for the day, however if only warm for 5-10 minutes this problem arises. If I turn off the machine and restart, the problem goes away and may or may not occur again.

Any ideas or advise is greatly appreciated,
Thank you again to all,
EG

I don't work on Hitachi excavators much but have to say there are multiple models of EX120s that have been sold in the US and imported that were not intended for the US markets. You should provide the full model designation, and a serial number is always a great idea.
Good Luck

John C. said:

You should provide the full model designation,

Click to expand...

The dash number will be needed.

Hi Everyone,
The machine is an EX120-3

Swing pressure switch defective? Do you have Dr ZX? Do you know how to get blink codes from the controller?

You could also try swapping the swing pilot line on top of the control valve with another function that works to see if the swing works by activating the function you swapped it with.

Sorry for the delay but Thank you everyone.
It's been working fine with warm up but will keep you posted.
EG