Originally Posted by stepside454
Like I said noise is coming from isolator relay under the hood .
Your isolator relay is controlled by the circuit board next to it. The relay is turned on when either battery bank raches 13.3 volts and drops out when battery voltage reaches 12.8 volts.
The relay is also energized with the emergency start button on the dash.
When the relay starts clicking, check the control circuit voltage in the two small posts. If the voltage is stable, the relay is bad. If the voltage fluxuates, check all connections before condemning the RV Custom Products circuit board.