On my 2006 23' I have a Micropulse. The black tank sensor (currently not working) is located on the dump pipe just above the pull valve. There is an RJ-11 telephone style wire connected to it.
The gray tank sensor is working (more or less) and I haven't scouted that out yet but I found a post that says it's on the gray dump pipe like the black tank sensor, just above the pull valve.
The fresh water tank sensor in mine isn't working. I'm told that it is above the belly pan and would require a hole to be cut to access it. Since we rarely use the FW tank (we do sanitize it, however) I haven't worried about getting it replaced. A few years ago the sensor was $55 but I see now it's $75.
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