Water tank sensors on Bavaria 47?

[nigelmercier]

I'm getting random results from the sensors on the fresh-water tanks on my Bavaria 47. Sometimes they read OK, but often the needle flicks up and down like a VU meter on steroids.

Has anyone got a schematic of how they work, and how they are wired?

Even Nigel Calder's (American, but otherwise excellent) Boatowner's [sic] Mechanical and Electrical Manual doesn't mention them.

 

[tillergirl]

Having just replaced my sender on my MAB, there appear to be two 'physical' types: a floating arm and a float that goes up and down outside a tube. Quite how they take a reading is beyond my knowledge but there is a positive and return wire so the wiring is basic. Power from the battery goes through the meter to sender and the return comes back to the meter. The 'instructions' with the sender says there are two types; a STD type which reads empty on a high Ohm reading (240 in this case) and full on a low Ohm (33). the other type is a VDO type which reads empty on low Ohms and full on high. I would guess a poor power connection first.

 

[nigelmercier]

[ QUOTE ]
I would guess a poor power connection first.

[/ QUOTE ]

I've had a play with the wires, but I think this one may be a bit more complex. The wires from the tank terminate on a circuit board PB42 in the image below:

I think what I really need to know is what the PB42 board does.

 

[tillergirl]

Yes I think you are right. The board is doing something clever presumably - or not now. Is P2 the gauge?