Installing new aerator switch, 2 wire to 3 wire. Help please

[Jebber]

I have a late 80's predator (18' center console bay boat), I've replaced the pump and bought a switch - has on, off & 30 second on every 3 minutes. Has 3 prongs labeled power, ground & pump
The old switch had two prongs, it was a pull type like old cars used to have..
Existing wires - one disappears into the hull, I'm @ssuming it goes to btty & then to pump (neither pump wire is the same color as the wire at the console)
The other wire is clipped into a prong on a fuse
I'm ignorant when it comes to most things electrical - any help is greatly appreciated!

 

[Grandad]

Not exactly sure what your question is. The original switch wiring will likely have only a feed to the switch from the battery positive, hopefully via a fuse, and a wire from the switch to the pump. The old switch simply interrupted the current path from battery to pump. The old switch did not "use" any power, but the new switch has a timing circuit that likely needs the addition of a negative wire from the nearest negative distribution bar. You would connect this wire to the terminal marked "ground". - Grandad

 

[Jebber]

Thanx grandad! I guess I wasn't clear, my apologies. You did answer my question - what wires go where. Except I don't know or see where the negative distribution bar is located. (Bus bar?). In fact, as far as I can tell there isn't a negative in the console (I'm going out to look again). There appear to several wires going to the steering housing under the console, would that be used as a ground?
Again, my thanx!

 

[alldodge]

Your boat may not use a negative buss bar, but all circuits need a negative return side to operate. Try to see where the black or negative wires go and how they are connected

 

[Grandad]

Hi Jebber. I'm not familiar with the predator's wiring layout. The pump itself must have a negative wire that you might trace back to the console, but it might also take another route to either a common point for other negative wires or it could run all the way back to the negative post on your battery. Kinda depends on who did the wiring. I would start by following the positive wire from the aerator switch to the pump and see if it's paralleled by the negative you need. It may well be that the pump's negative wire comes from a convenient point in the console. As long as the "ground" terminal of the switch is connected to any negative, it will probably work without issue. Usually, one should use the same negative feed to operate the switch's timing circuit as the negative feeding the load (your pump). In reality though, any negative wire will carry the additional amount of current used by the timing circuit, so don't jump through too many hoops to find specifically the pump's negative. - Grandad

 

[Jebber]

Thanx all, hopefully I'll get it done today!