Dometic 8700 Series "Red Light of Doom"

[andyshane]

This is a new rig, and I've had this problem, twice.

Others have reported the same thing happening, with their Dometic 8700 mascerating toilets. Once the Black tank reaches 75%, the common recommended minimum prior to dumping, one or both toilets can quickly "go Red," meaning the Red full tank icon illuminates and electrical power is inhibited. Putting a finer point on it, if one toilet has a red icon and the other is still yellow, the latter is still for the moment functional.

'Problem that owners are having is, the red light remains on after  a Black tank dump and it often will remain on, following dump and rinse.

Same deal, however: if one toilet was yellow prior to this condition, it will revert to a blank display and work normally. But, there is some glitch in this design and/or programming that can leave one or both toilets "stuck" on Red despite an empty/clean tank.

In our case, we are a new rig, a 2019 Newmar DSDP 4018 purchased at the end of summer. We have no children or teenage girls, and eat lots of fiber. No, seriously, we use the toilets delicately, ie a two-flush system, modest paper usage, no wet wipes, etc.

The fix for this condition is relatively simple: find the control module for the affected toilet -- it looks like a black deck of cards -- and clip the yellow wire. That defeats the Full level sensor, restores normal operation. The caveat of course is, you've now defeated the Full inhibit function and can overflow.

In the aft-bath DSDPs with their novel escape door (a handy way to converse with neighbors while attending to business), the process is painfully easy: open the escape/socializing door, reach into the now exposed toilet cavity from outside and unclip the yellow wire. For the powder room and many other applications, the module could be anywhere on its 6-foot harness, like under the sink or inside the wall. For DSDP owners, some have found the powder room module located behind the "Newmar pegboard."  In our case, it is mounted above the pegboard and behind the adjoining plastic fairing. I took a photo, for reference.

Having endured this condition twice in our first six months of usage, I'm creating a simple fix: each toilet will have a nearby guarded emergency-use-only switch labeled SENSOR OVERRIDE to restore operation when flushing is inhibited by a false Full indication.

I'll save this with lots of tags, to shorten the learning process for those who'll encounter this problem, on the road.

 

[manholt]

I feel you pain!  We installed  "SeeLeavel" on all 3 tanks. We back flush after dumping and we fill black tank with 10/15 gallons of fresh water, with a 1/4 cup of Dawn when were on the road...over kill? Maybe, but it stopped the red light.

Also, make sure your plug in fuse is 20 Amp!  Mine came with 15 Amp & that's for marine use only!

[hermanmullins]

44 minutes ago, AndyShane said:

(a handy way to converse with neighbors while attending to business), the process is painfully easy: open the escape/socializing door, 
 

Hard to erase that image from my mind.

Herman

[andyshane]

I had some leakage in this area last trip, turns out someone at Newmar got a little hamfisted and installed the ABS pipe elbow that feeds aft sink and shower drainage into the gray tank.

Since the black and gray tanks are above the fresh and hidden behind the pegboard in Dutch Stars, I installed a two-sensor water alarm and put a second cutoff switch next to the one featured in this entry. Owners might consider checking the carpet and adjacent pegboard in this compartment as part of their pre-trip inspections.

 

Edited January 11, 2021 by andyshane
Bad grammar

[dennypearson]

I have been having troubles with my masterflush 8759. While investigating I was told that dometic was discontinuing the 8759 and replacing it with model # 8746. Can anyone confirm this, Thanks.