Replacing bilge pump strange original wiring

[littleape]

I'm replacing a bilge pump that came with the boat and the original wiring is strange. My new pump has 2 positives to trigger the pump, one is auto mode and the other is manual. The pump I'm replacing is strange, it has 3 wires coming from the console switch, 2 grounds and 1 positive. The positive is constant, with the dash switch OFF the two negatives are "live", with dash switch set to ON (manual override) one of the negatives is switched off and this triggers manual override of the pump. This is so weird.

So, I need to reverse the manual override so it's a positive not negative trigger for the new pump. I thought maybe I could move the connectors at the back of the dash switch but it looks a bit messy there and with the fuse right there not sure how that would be affected.

I'm thinking of using a relay to trigger the manual override of the new pump.

30: + fused source
86: + fused source
85: - trigger from dash switch (reversed, when switch is ON power is removed and 87a becomes energized)
87a: + to bilge



Anything off with my logic here? I've done + and - triggers of a relay before but not a reversed negative like I need here.

 

[sam am I]

That is odd.......

WTH, when in Rome, cept




So as wired, constant +12V (but now only to 30 and 86) and using/keeping the original switch's config of switching ground/lows out and converting/"reversing" it for a normal switched +12V pump with a relay.......one correction,

30: + fused source
86: + fused source
85: - trigger from dash switch (reversed, when switch is ON power is removed and 87a becomes energized)
87a: + to bilge 87: + to bilge

If you use 87a which is N.C. and 85 goes low ("- trigger from dash switch"[switch turned to on]), the bilge would have been running with the switch set to off and then stopped when the switch's position is set to on....lol, use 87, it's N.O.

So then now, and again when 85 goes low ("- trigger from dash switch"[switch turned to on]) 87 now switches out +12V, pump now turns on.....Switch on, pump on.

Ya sure you can't get in there and rewire this thing normal? Adding the relay to the existing active low wiring schema seems perhaps just as, if not more consuming...

 

[sam am I]

with dash switch set to ON (manual override) one of the negatives is switched off

To be clearer, the wire("one of the negatives") you've referred to has to be the source wire for the "- trigger from dash switch" at 85. This source ("one of the negatives")wire is actually being grounded ("switched off") when the switch is set to on.

This is my understanding anyway, your old pump is ground switched as it was wired to a constant +12V

 

[littleape]

Hmmm the current dash manual bilge switch circuit is closed when set to OFF. With switch set to ON (trigger manual pump) the circuit becomes open. 87 would work if this circuit was logical and was open when dash switch is OFF but this thing is backwards so I need 87a which will be closed to 30 when the dash button is ON and that circuit becomes open.

(3) total wires from dash to the pump
(1) wire is positive
(2) wires are ground, both are closed to positive wire when switch is OFF, one becomes open to positive when switch is ON


This is so bizarre, makes my head spin a little.

 

[littleape]

Here is a picture of the dash switch.

1 pin has constant +
2 pins have constant -
1 pin is switched - and with button as pictured in OFF state that switched - is hot


Each switch on this panel has a breaker so I'm not sure how I can modify this so the switched pin is positive and in reverse to what it does now.

 

[sam am I]

k so question, in your most resent post/picture, the switch terminal going to the pump wire (gray) you've labeled it "- trigger" and also annotated "closed in this position" and "open if toggle flipped and old pump starts".

I also note that this pump wire (gray) is disconnected, which, is for all intense proposes, is also "open", correct?

So, Is the old pump running with the wire disconnected as pictured?

 

[littleape]

So, Is the old pump running with the wire disconnected as pictured?

Did not test, but the unplugged wire in the picture is one of the two grounds at the pump. I already had the wires at the pump disconnected when I unplugged this wire from the dash switch. But, if the pump was still connected on the other end than disconnecting this wire at the back of the button would trigger manual pump since I opened that circuit. I'll confirm in a little bit when I go back to the boat but I'm 100% sure, verified with multimeter, one of the grounds gets opened when the dash button is switched ON.

I've never run into a setup like this where a trigger action is done by opening a circuit instead of closing.

 

[sam am I]

But, if the pump was still connected on the other end than disconnecting this wire at the back of the button would trigger manual

Agreed, yes it should have if the thing works as we're guessing.......Do you have a make and model number off that old pump? Also perhaps a number off that switch too? The switch is a lighted 2 position switch? Sets to Auto or Manual?

I've never run into a setup like this where a trigger action is done by opening a circuit instead of closing.

Me either but, I'm also not sure sure all cows have brown eyes because I've not seen all cows!

 

[littleape]

The pump is a 2 wire Rule pump with some other brand external float switch, will check brand/model shortly.

Yes the dash switch is 2 position, red led illuminates when it's switched ON manual override. Auto in the other, as pictured, position.

 

[sam am I]

Maybe there is already a relay somewhere inline downstream that when the "- trigger" wire opens, the relay un-energizes disconnecting the manual +12V feed to the pump and thus switches over the pump's +12V feed to auto via the float? Just guessing but.....something along these lines perhaps.




Strange stuff, who makes the boat? Is it stock?

 

[GA_Boater]

What brand/model is the new pump?

 

[sam am I]

Drawing edit to in #10, the relay above should have been drawn as energized/using the float's +12V......But I'm sure you get the gist.

 

[littleape]

Ahhhh finally figured it out, it's a little sneaky the way its wired up.

The dash manual override switch reverses the polarity of one of the wires. When it's OFF the wire is a ground, when it's ON the wire is +12.

Weird way to wire something up, is this a common practice in the marine world?

No need for a relay.

 

[GA_Boater]

Again - What brand and model is the pump? In case a future buyer needs help.

 

[littleape]

It was Rule 500 and the switch was also a Rule

It's the reversal of polarity on the trigger wire that totally threw me off after I first checked the connector.

 

[littleape]

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