Dc to dc charger will not turn on

Orion -Tr Smart 12/12 18amp charger will not turn on.
App says unit off
low voltage or engine off
but engine is on with 14.2 v
i got a 120 error code sometime

Ford E350 chasis
Go Power PWN -10 SQ solar controller
WFCO WF9560 distribution panel

Connected chasis battery direct to rv battery – charge

What can I do?

How did you connect the remote jack ?