I just replaced the shower sump pump switch on my 2008 R-25. I had the opposite problem. My switch would not turn on. I like the suggestion to pull the fuse when the shower will not be used to avoid draining the batteries if the swtch sticks on, but it would be better if the sump pump was wired to the DC switch panel. That is a project for another day.
Here's a rough procedure for changing the switch;
Remove the access panel under the sink in the head.
Put a pad over the magnetic door latch to avoid banging your head.
To avoid skin removal from the back of your hands and wrists during the rest of this procedure, remove the sharp fiberglass edges from around the access hole with a utility knife and smooth with sandpaper.
Turn off the pressure water.
Use a headlamp for the balance of this procedure.
Loosen the clamps for the two water hoses that go laterally to the shower. Slide the clamps 6 inches to port and loosely tighten them for temporary storage. Pull the hoses off the T-fittings and push them out of the way.
Reach in and extract the wiring loops. From the boat there is a brown and black wire. There should be twelve volts across them.
There are four wires that come out of the sump tray. Two gray wires come from the switch. Two other wires (I forget the colors) come from the motor.
One of the gray wires from the switch is connected using a heat shrink butt connector to one of the wires coming up from the boat. The other gray wire from the switch is connected using a non-heat shrink butt connector to one of the two wires coming from the motor. The other wire from the motor is connected to the second wire coming up from the boat using a heat shrink butt connector.
I cut the gray wires from the switch and verified that I could turn the pump motor on and off by connecting the motor directly to the power from the boat. Therefore, I concluded that the problem was the switch and not the pump motor.
Next, carefully remove the four screws from the top of the plastic tray that houses the switch and motor. You'll need a very short phillips head screwdriver and lots of patience to do this slowly and avoid dropping the screws.
I had to completely remove the cover through the access port. This required bending it slightly to work it around what I think is a heater hose and a cable to the depth sounder and up through the access hole.
Remove the cylindrical screen from the sump input. This requires bending the edges of the tray outward to work the screen past the two mounting tabs.
Loosen about two turns the starboard mounting screw for the switch. This screw is over a slot on the swtich and should not be removed completely.
Remove the port mounting screw for the switch.
Extract the switch.
If the problem was the motor, you could extract it after the switch by pushing in the two mounting tabs, pulling up and then pulling it off the output hose.
I ordered a new switch from Defender for $36.
Replace the switch. Use butt connectors to rewire.
Verify operation before proceding. The switch has a small toggle on it with which you can manually move the hidden float up and down.
Heat shrink the butt connectors.
Reinstall the screen and plastic tray cover.
Reconnect the shower hoses to the T-connector and replace the access plate.
Really appreciate that next shower.
Good luck!
