On my 2011 the shutoff valve is under the kitchen sink. I had a similar leak it turned out to be the brass ferrel that goes in the tube and creates a seal was damaged at the solenoid. I have the bath and half so I don't know if your valve is in the same location. The solenoid has the foil tape wrapped around it. I added a shutoff valve near the solenoid. You access the solenoid from the outside lower vent. Hope this helps.
2011 Berkshire 390-rb-40, upgraded tires and front axle airbags, 2012 Jeep Wrangler 2 door, Blue Ox baseplate and BlueOx aladdin tow bar, Blue Ox Patriot brake system, wiring run through right frame rail and homemade led taillight bar.FB.