Mine is a 2005 CCD 19' Bambi. The black water sensor is just up and behind the dump value. It is NOT inside the belly pan. Look for a small black cap that is drilled into the 3' black water pipe. You will see the telephone cord connecting to it. Hope that helps.
You may try unplugging and cleaning the connector at this end too. (Mine had a problem at this connection point too.)
It is relatively easy to unscrew and replace the sensor if you see it. Use Teflon tape like any other plumbing connection. (Make sure the tanks are empty first...
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