Grey and black tank sensor question

[larry2c]

We had our maiden voyage with our new TT week before last. On thing I noticed was that the grey tank went from 1/3 to full in the blink of an eye. Since our tanks are 56/30/28 fresh/grey/black and we had used only about 1/3 of the fresh water it seemed unlikely that we had a full fresh tank.

Today I crawled under the trailer and looked at the wires on the sensors. What I see is that the color of the wires on the sensors is different on the black tank vs. the grey. On the black tank the bottom sensors (two assuming the white is ground) yellow & white > middle green > top orange. On the grey tank I have
bottom green & white > middle yellow > top orange.

I see that for both tanks the wires run into a junction block so maybe my observation doesn't mean anything. However, if I'm right and this is a mistake, can I simply clip the wires on the grey tank, switch the green & yellow wires and be good to go?

[andymil]

I would disconnect the top two sensors and see which lights are lit. Make sure there is enough water in the tank to cover the bottom two sensors. Then attach one of the wires you removed to the second sensor and check the lights. You should be able to confirm which wires control which lights. You should be able to take the wires off of the sensors by removing a nut on the sensor. Unless the wires are short, you can move the wires without cutting them.

It seems that the way these trailers are put together, anything is possible! Yesterday I put two gallons of water (with a cup of Borax dissolved in it) into my empty black tank and it went from empty to 1/3 full.

When it dries up outside, I'll check the wire colors on my tanks.

[larry2c]

I just wanted to post a follow up on this issue - I switched the wires on the grey tank to match the black tank and now the sensor/display work properly. Thank you to Andy for pointing out that the connections were screw in and not soldered on (I couldn't tell with the large globs of sealer on each connection).

Speaking of sealer, should I get some sort of sealant and put on the connections to keep them from corroding? I assume that is the purpose of the red stuff on each connection.

Just in case this may help someone else, the wires for the sensors seem to need to be in this order

White - near bottom of the tank away from the other 3 wires
Yellow - bottom sensor
Green - middle sensor
Orange - top sensor