Black tank sensor removal issue

[Crothman]

Hello, new to the forum and would like to see if anyone had this problem. I have a 2018 Outback 266RB travel trailer and I need to replace the black tank sensors, problem is, there's an underbelly sheet covering the entire back end of my RV. I know the sensors are on the tank and Keystone said to start cutting as long as you put it back. That doesn't help me since i don't know where it is and might not be the best thing to do. I have attached a picture to show the underbelly and if there's a better way to access it, i'm all ears.... and fingers.

[chuckster57]

Start at the end, remove the screws that hold the coroplast up. I do 2 screws at a time, on a creeper side to side until you have enough to expose the tank. Then I just shimmy across the coroplast to do the repair. When done, start putting the screws back in one at a time side to side, starting at the attached end.

Added: sensors will be on the side of the tank.

[travelin texans]

Follow Chucks good advice!
If they happen to look like rivets rather than screws you should be able to pry them out with a nail bar & replace with screws & fender washers.
I would not cut the coroplast unless absolutely necessary.

[chuckster57]

Why do you think you need to replace the sensors?

[Crothman]

Thank you, Chuck and Travelin Texans but would the sensors be on the same side as the pull lever or the opposite side? Otherwise i'll try what Chuck mentioned as they look like hex screws. I'll reply back hopefully tomorrow and take pictures in case someone else has this issue. Thank you guys for this bit of info. Much appreciated

[chuckster57]

More often than not they are on the drain side of the tank, but I’ve seen them on either side, I think it depends on the manufacturer and where the harness is ran.

[wiredgeorge]

Not sure it makes any difference as I have a different camper but my probes are towards the inside of the camper and the harness runs along the frame for both my black and gray tanks. This would be the opposite side as the handle in your case. I used Horst Miracle Probes that little covers to keep stuff off them. I changed all of mine on all tanks but I don't have coroplast under my camper.

[travelin texans]

Originally Posted by chuckster57

Why do you think you need to replace the sensors?

Repeat!
Why do you think replacing them is necessary?
If it's due to poor accuracy, save yourself a lot of work, $$ & aggravation & accept the fact they're pretty much useless, just like every other rv that has them. Unless you've found some miracle sensors no else has ever tried the replacements won't be any better than what you currently have.
Drain, flush & clean the tanks, especially the black tank, as good as possible then add a good long squirt of Dawn dish soap with about 5 gallons of water then travel to your next stop then drain & flush again. This may, or may not, help the sensors accuracy, at least til you've filled the tanks a couple times again.
There's 1000s of threads on every brand of rv forum about the inaccuracies of these sensors & tens of 1000s of solutions to TRY & correct them, but from my experience your best option is to learn the sound of the toilet flushing to know when the black tank is nearing full & how many showers it takes to fill the grey & forget the sensors.

[wiredgeorge]

Originally Posted by travelin texans

Repeat!
Why do you think replacing them is necessary?
If it's due to poor accuracy, save yourself a lot of work, $$ & aggravation & accept the fact they're pretty much useless, just like every other rv that has them. Unless you've found some miracle sensors no else has ever tried the replacements won't be any better than what you currently have.
Drain, flush & clean the tanks, especially the black tank, as good as possible then add a good long squirt of Dawn dish soap with about 5 gallons of water then travel to your next stop then drain & flush again. This may, or may not, help the sensors accuracy, at least til you've filled the tanks a couple times again.
There's 1000s of threads on every brand of rv forum about the inaccuracies of these sensors & tens of 1000s of solutions to TRY & correct them, but from my experience your best option is to learn the sound of the toilet flushing to know when the black tank is nearing full & how many showers it takes to fill the grey & forget the sensors.

I replaced mine and only took a few minutes but I didn't have coroplast. Didn't do any good but I replaced them, the wiring harness, the board and none of it made any difference. All the gauges for the tanks still were totally inaccurate.

[flybouy]

Maybe the western edition units are built different or maybe the water is better I can't explain it but I have owned several new campers over the years and have yet to get one with accurate tank sensors. FW is somewhat close but I ignore the black and gray. Just my experiences, YMMV.

[Crothman]

I just removed several 3/8 screws and although they came out quick, i'm just doing it just maintenance I suppose. The sensors are cheap enough i looks like taking the coroplast off seems to be like a 20 minute job for the screws, just that I would like to have something new and working. It's giving me wrong accuracy and although I tried everything from strong RV tank cleaners to using the wand, still says 3/4 full. Yes when its empty it takes a lot to fill up a 35 gal black tank. But at least I know what to expect. Thank you everyone for giving advice.

[chuckster57]

If you put the same style sensors in, you’ll need to be very diligent about cleaning the tank.

Make note of the colors of the wires, and I would test the “sensor pack” before replacing any sensors. Disconnect the three colored wires and leave the white one attached.

Check the panel, should read empty. Then jumper from the white to the wire you took off the bottom probe- should read 1/3.
Move jumper to the wire from the middle sensor-should read 2/3.
Move jumper to the wire from the top sensor-should read full.

If it doesn’t then the sensor pack needs replacing not the sensors.

[wiredgeorge]

Originally Posted by chuckster57

If you put the same style sensors in, you’ll need to be very diligent about cleaning the tank.

Make note of the colors of the wires, and I would test the “sensor pack” before replacing any sensors. Disconnect the three colored wires and leave the white one attached.

Check the panel, should read empty. Then jumper from the white to the wire you took off the bottom probe- should read 1/3.
Move jumper to the wire from the middle sensor-should read 2/3.
Move jumper to the wire from the top sensor-should read full.

If it doesn’t then the sensor pack needs replacing not the sensors.

What is a sensor pack? I replaced EVERY bit of this system on my camper because I am suborn. I replaced the probes with Horst Miracle Probes which work same but have hoods to keep TP from clinging. I replace the harness going up to the idiot lights and then replaced that part as well and it never changed the reading I got. I know my tanks were empty and I got the right resistance as the Horst tech support folks gave me those values. Never made the thing work right and I am still baffled. I never really cared that much about the wrong values and that is what i have had in every camper I have owned only that I couldn't get the idiot lights to reflect even the approximate levels for the tanks.

[chuckster57]

The “sensor pack” is the plastic thing that has 4 wires attached to it. Three wires have eyelets and the fourth is bare.

I’m color blind and working with a brain that has been treated for Covid (alcohol) so I may not get the colors right. Red is the wire that goes to the monitor panel. The bottom sensor is the ground and is usually white. 1/3 probe gets the yellow,2/3 gets the green and full gets the red.

You can tell because the resistor is in the plastic, and if you look for the “sender” wire (bare end) 1/3 is the farthest away. 2/3 is in the middle and full is next to it.

The test I described works if the ground is good and the sender wire is hooked up to the trailer. Caveat: fresh tank will read 1/3, and 2/3 but won’t read full with the jumper. KIB tech support told me years ago that you need a specific value resister in the jumper wire to compensate for the minerals found in fresh water.

I have used this method for over 10 years and it has yet to fail me.

If tank always reads empty, most common issue is bad/missing ground. Tank always reading 1/3,2/3 or full, test the sensor pack and check for the right wire to the probes. If you want more specific info feel free to PM me and I’ll answer when the “medication” wears off.

[Life-in-Him]

Originally Posted by chuckster57

StarWhen done, start putting the screws back in one at a time side to side, starting at the attached end.

Added: sensors will be on the side of the tank.

I've used another jack or jackstands supporting a 2x6 in the Middle of the coroplast to get it partially up.
Then the screws go in easier.

[bobbecky]

We don't pay any attention to the tank level system, so it's not a problem for us. Having said this, we know of others that have installed or have had installed the SeeLevel system, which leaves the existing sensors in place and adds new sensors which install on the outside of the tanks and they have found this system to be quite accurate. Not sure of the cost, but it works. https://www.garnetinstruments.com/rv-shop/products/

[travelin texans]

Originally Posted by bobbecky

We don't pay any attention to the tank level system, so it's not a problem for us. Having said this, we know of others that have installed or have had installed the SeeLevel system, which leaves the existing sensors in place and adds new sensors which install on the outside of the tanks and they have found this system to be quite accurate. Not sure of the cost, but it works. https://www.garnetinstruments.com/rv-shop/products/

I have this same question every time I read that "found that system to quite accurate", HOW DO YOU KNOW IT'S ACCURATE? I guess on some you could stick a yard stick down the toilet for an actual depth, you could look down the toilet I suppose but doesn't tell you much & typically the tanks are black so even if it was exposed you couldn't see anything through it. My last 2 5ers the toilet was about 4' above the tank with 2 45 degree bends in the piping so measuring wasn't an option nor was looking.
So how do you know with any certainty it's anywhere near accurate?
The 7 - 8 rvs I've owned the Grey & black sensors always read 1/3 or 2/3 whether full or empty, not sure about the FW sensor as we rarely added water or used the pump.

[chuckster57]

See level is an excellent system, I have installed a few. Tiffin used glue on sensors on the exterior of the tanks and they always seemed to work real good. It’s a matter of $$ IMO, and most manufacturers use the cheapest system.

[Folkie]

Originally Posted by travelin texans

I have this same question every time I read that "found that system to quite accurate", HOW DO YOU KNOW IT'S ACCURATE? I guess on some you could stick a yard stick down the toilet for an actual depth, you could look down the toilet I suppose but doesn't tell you much & typically the tanks are black so even if it was exposed you couldn't see anything through it. My last 2 5ers the toilet was about 4' above the tank with 2 45 degree bends in the piping so measuring wasn't an option nor was looking.
So how do you know with any certainty it's anywhere near accurate?
The 7 - 8 rvs I've owned the Grey & black sensors always read 1/3 or 2/3 whether full or empty, not sure about the FW sensor as we rarely added water or used the pump.

Having OCD, I did a "calibrated" fill on our camper when it was level using an in-line flow meter on a hose before we started using the tanks. I wrote down when the display changed and put the info on a chart by the in-Command display. Info was way off of the 1/3, 2/3, full levels, but it gives me a better idea of where we are. It still doesn't solve the issue of the sensors getting fouled.