Lots of Class B RV's have an Intellitec Battery Disconnect relay.
From the service manual: http://www.flemingsalesoem.com/intellit ... 9100-2.pdf
Relay won't disengage:
- Check fuses on relay
- Check battery voltage, must be greater than 10.5 volts
- While switch is engaged, check voltage across the coil terminals (+ on the "S" terminal and ground on the "I" terminal) If 0 volts, replace panel, if + voltage, replace relay.
The switch can be located far away from the actual relay and would look similar to this: