First, let me say it was all my fault because I trusted the guy at Thor Technical Support. My black tank started showing errors on the tank level. I cleared it before using my spinning washer thingie made to flush the tank. Not this time. Purchased new sensors and crawled under the RV in the late evening to see their location on the tank. I didn't use a flashlight (my bad) and it looked like I could get to all of them. There are two types of sensors - one is replaceable and the other is glued to tank and is not. Called Thor Technical Support and asked which was installed on my RV. He said it was the replaceable kind. Got ready to do the swap out
They are not.
Used Horst Miracle Probes. Better design than original crap (pun intended).
From the photo, you can see that the chassis rail runs parallel to the sensor side of the tank. Not enough room for a drill to fit and its a plastic tank so I purchased an unibit and a 90-degree drill chuck which took a few days to get.
So a project which I could have done in an hour spread out over four days.
Best video on the subject : https://youtu.be/iABA43tHVXI
Top sensor I did not replace. Will have to jumper wire to location on tank I can drill. It's up against the gray water one which has a section that goes under the shower. Future project
The white wire is the common return at the bottom of the tank. I also put some tape on the wire bundle which was laying on the top of the chassis rail. Other wires have sleeves when they are touching metal, not these.
All the tools I used