Fault code

I have 2 Sun Power inverters (5200 and 3200) and recently the 3200 shows a fault code 9 of 1000 0000 0200
The manual says it is "AC voltage sensing missing per UL or Ground Fault"
No idea what to do. Thanks in advance for replies.
The manual says it is "AC voltage sensing missing per UL or Ground Fault"
No idea what to do. Thanks in advance for replies.
Comments
Similar for solar panel side. If the fuse is good, The + terminal should be near ground, and the - terminal near Vmp-array to Voc-array (according to one manual I read, the GT Inverter has a positive grounded, via the fuse, array--Many GT inverters are configurable for positive or negative ground arrays).
https://www.manualslib.com/manual/864752/Sunpower-Spr-5200.html?page=9#manual (page 9 has wiring diagram)
-Bill