go from one of the accessories and tone back to the relay /switch
If that fails, pull the fuse and power from the relay side toward the relay. Voltage should show up downstream. Relay will not work due to no ground trigger.
The way I read your statement is power flows from switch to relay but relay will not contact. If power is at relay then the ground is not working, but that could come from the accessories panel back to relay or from the switch. I no longer have my books for your RV. I sold mine some years back and all that stuff went to the new owner.
If you jump power from relay then does the accessories start working.