Need help with float switch/bilge pump....bad float switch?

[snowman48047]

I'm pulling my hair out....I think I have a bad float switch but... Dash switch for bilge pump is on, float switch is down but bilge pump is running. Also I'm only getting about 5 volts through the float switch. If the float switch was bad wouldn't I get either a full 12 volts or nothing?

 

[alldodge]

Dash switch for bilge pump is on

The switch is ON and the pump is ON, sounds like that is the way it should be. To check you float switch is one side should be 12V and the other nothing unless the dash switch is ON. Here is the typical wiring, and may not have the alarm link

 

[snowman48047]

Mine is not wired like that. There was no float switch originally. I added it. From Lund turn the dash switch on to run bilge pump.

Now, since i added the float switch; power from battery through fuse, to dash switch, to float switch, to bilge pump, to ground. Simple loop. The pump should not run with the float "down" but it does. That's why I'm thinking power is shorted through the float switch.

 

[alldodge]

Then I would agree it probably is being wired like that. What kind of switch is it, water sensing electronic, snap switch, or other?

Could disconnect the switch and read the resistance thru it. Don't get the 5V, its like it may be getting power thru the ground side (shouldn't happen just a thought)

 

[snowman48047]

It's just a cheapo attwood float switch, no cover, about $15-$20. With the float "up" (on) I had almost no resistance and with float "down" (off) it was around 64 ohms. Not sure if that means anything.

I cut the float switch out and reconnected the boat wiring and it works as it did from factory. I'll put in a new one.
I was more confused with power (+12) coming through the float switch in the down or off position. I've had problems with the bilge pump system every 2-3 years since new in 2000.

 

[alldodge]

Being off and 64 ohms isn't much, I can see why the pump kept running

 

[mjf55]

The float switch is a simple switch, open or closed. It appears to close ok (0 ohms) , but the open showing 64 ohms is not good. Replace I'd when you have the switch removed, it still reads that way

 

[GA_Boater]

Turn off the dash switch and lift the float. If the pump runs with the float up, you inadvertently wired it as in AD's diagram. That is the best way to wire it anyway because you can still run the pump if the switch fails.

BTW - Are you measuring ohms when the pump is running? Can't do that with voltage present.

 

[snowman48047]

If I turn off the dash switch and lift the float nothing happens; there is no power.
I'd I turn on the dash switch and lift the float it runs as it should.
If I turn on the dash switch and DO NOT lift the float the pump still runs, but with only about 5 volts. It should NOT run with the float switch down. Hence my assumption the float switch is no longer able to "open" the circuit and shut off the pump.

I did the ohm check with the float switch disconnected from the boat.

 

[bruceb58]

you should change your wiring so that a float switch runs the pump no matter what the float position is in. You should wire it like the drawing above.

 

[snowman48047]

I installed the new float switch per the diagram provided by AllDodge. I don't have the high water alarm but everything works as it should now. Thanks for the help everyone.