I'm trying to add an aerator timer switch into a '19 Tracker Pro 170 that currently has a single switch that controls both the aerator and bilge pumps:
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The back side of that panel looks like this:
IMG_20220806_172042319.jpgIMG_20220806_121212593.jpg
By process of elimination, i.e, removing the wires one at a time while the pump was running, these wires control the bilge pump and have nothing to do with the aerator:
IMG_20220806_172042319_4.jpg
Here's the part I don't understand - there are 13 volts across the two wires physically attached to the switch:
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There are also 13 volts across the negative wire at the switch and the fuse wire, which I guess is obvious, because it's bridged from the switch wire:
IMG_20220806_172042319_3.jpg
What I don't understand is when the pump is turned on via the 3 position switch, the voltage remains 13 volts across both poles of the switch, but disappears between the two wires shown above. As a result, I can't figure out how to wire in the new switch, which requires voltage inputs and then an output to the pump.
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I tried using the double red wire coming off of the fuse as the output and the switch wires, which always have 12 volts as the inputs, and the voltage came through when the new switch was turned on, but it didn't run the pump.
Does anyone understand what's going on here? It's almost like the pump runs when the voltage is dropped to 0.