How to Replace Bilge Pump Switches

What You'll Need
New bilge pump switch
Wire brush
200-grit sandpaper
Wire cutters
Wire strippers
Wire crimpers
Fuse of the correct size and amperage

Take care when replacing bilge pump switches that you disconnect the old wiring and connect the new wiring correctly. Ensure you ground the switch and fuse it so it will operate correctly and will stop working if it becomes flooded or damaged. Follow the steps outlined below to replace switches for bilge pumps.

Step 1: Choose the Correct Switch Type

Always replace a computerized switch with the same type and a floating switch with a floating switch.

Step 2: Remove the Old Switch

Disconnect the power supply to the bilge pump at both the terminal and the battery. Remove the fuse from inside the terminal. Disconnect the switch wires from the terminal and the battery. Disconnect the switch mechanism from the bilge pump.

Step 3: Clean All Connections and Fastener Pilot Holes

Inspect all connections at the terminal and battery for corrosion or rust. Clean the connectors thoroughly with a wire brush. Remove any dust and dirt from the pilot holes for screw fasteners for the switch.

Step 4: Check the Dashboard Hole is the Correct Size

The switch needs to be installed in a hole 2-3/16 inch by 2-1/16 inches in size in the dashboard. Make sure the hole is the correct size and sand off rough edges with 200-grit sandpaper.

Step 5: Insert the Switch

Attach the switch by its front panel to the dashboard with the 4 black galvanized screws provided. Align it correctly in the panel so you can turn it on and off without striking the dashboard or other instruments.

Step 6: Wiring the Switch to the Terminal and Battery

Consult the wiring diagram provided with the bilge pump switch. For a 3-wire computerized switch, connect the brown and red wires to the lower connectors on the terminal. Attach the switch main wire to the top connector of the terminal. The black wire will be the ground for the pump. Leave it attached to the pump. The brown wire will attach the terminal to the pump. For a floating switch, the ground wire of the switch is connected directly to the pump, while the floating switch wire is attached to the top post of the terminal.

Step 7: Attach the Hot Side Wire from the Terminal to the Battery

The hot side wire goes to the positive connector on the battery and the ground wire is attached to the negative connector, on both types of switches.

Step 8: Install Fuse in Terminal

Install the fuse size specified in the installation instructions into the terminal to operate the switch and guard it against power surges or power failures.

Step 9: Restore Power to the Switch and Test

Ensure the terminal, battery and switch connections are secure, then turn on the switch to test it. The switch will have 2 ON positions, Auto and Manual. The switch turns off the pump once you release the switch in Manual setting. The switch turns off in Auto setting once the pump has drained water below the minimum active line. Check for the red light on the switch to show it is working.