Here or there...

The same, DrainMaster, valve is used on the gray water outlet as is used on the bathtub and black water drains.  One difference in the gray water drain is the use of two switches.  One is located inside the curb-side tool box.  The other is located in the vehicle cab.  The two switches are connected in parallel.  Details of the connections are shown in the wiring diagram on the drain valve page.

As you may see in the valve assembly photo below, trailer taillight connectors allow disconnection of the valve.  For this dual switch connection, I created a "Y" connector from those connectors.  The switch in the toolbox, shown below, connects through the junction box on the outside of the tool box.  The second switch, in the vehicle cab console, is connected through four conductors extended, under the body, through plastic wire loom.  The same conduit run includes conductors for the collision detection speakers and power for the right side turn/marker lights.  12 volt power for the cab drain control switch is routed into the cab console from the attic control console.

Photos below show some details of the installation.

(Click an image to enlarge)