Resolved Dometic Masterflush Control Board

[Texas Clodhopper]

Can someone please point me to where the general location of the control board for the rear bath masterflush 8700 toilet is located?
The waterfill button works but the flush button doesn't. The green light on the pad is lighted so its not the dreaded false red light warning.
2017 Ventana 4369.
Thanks.

 

[Sealyn]

Did you try swapping controls with the other bath?

 

[Texas Clodhopper]

Did you try swapping controls with the other bath?

Not yet but I'm trying that in a few minutes. I know I can jump two terminals and if it flushes, its not the control board. I was just trying to get a hint of where the board is before driving to my storage and swapping the controls.

 

[Magua]

On my Essex, the control module is in the closet on the left hand side, under the false floor.

 

[Texas Clodhopper]

Update: I swapped the switches and get the same results.

 

[Neal]

I believe the controller is under the washer/dryer area behind the louvered grill but not sure. If the macerator is jammed it could be causing this. You can also look behind the toilet to make sure the wiring is intact, or unbolt it from the floor and rotate it for inspection. It's 12V so cycling power such as disconnecting it's connection or coach 12V power may be work a try.

 

[Texas Clodhopper]

The controller is under the toilet for the master bath and behind the pegboard for the half bath. Found it Newgle.
Neal, I think you have it right. I added some powdered dishwasher detergent to help clean the black tank and I may have gotten a little too rambunctious. I'm going to let it soak for a few days and if it doesn't dissolve, I'll take the toilet up and disassemble the pump.

 

[Neal]

If your half bath is gravity like mine then that's the better path to black for cleaning. I use liquid cascade.

 

[Neal]

Maybe try boiling a pot of water then pour it into the toilet and see if that helps break apart any bonding that may have occurred.

 

[Texas Clodhopper]

If your half bath is gravity like mine then that's the better path to black for cleaning. I use liquid cascade.

My half bath is not gravity-fed, unfortunately, and next time I'll use the liquid.

Maybe try boiling a pot of water then pour it into the toilet and see if that helps break apart any bonding that may have occurred.

Good thought on the boiling water. Thanks.

 

[Rich W.]

Liquid would be better - just use low sudsing (dishwasher det) and not regular dish soap. I had a bad experience with suds once and wont do that again. I have a bunch of old solidified cascade and I soak it in water in a bucket until its dissolved and then add it.

 

[Neal]

@Texas Clodhopper any new chapters to this story?

 

[Texas Clodhopper]

@Texas Clodhopper any new chapters to this story?

Resolved yesterday. I used a toilet bowl plunger which stirred up the detergent. I let it set for about 10 hours and tried again to flush and whamo, it flushed with no issues. Next time I'll use a liquid detergent.

 

[Texas Clodhopper]

As an additional follow-up about using dishwasher detergent in my holding tanks. I've had problems with the gray tank level sensors for quite a while but after using the dw detergent the sensors are back working correctly. I purposely had my gray tank over half full when I added the detergent and after driving for 200 miles I dumped the tank. The water was actually black and I can only assume it was mold that had accumulated in the gray tank. Really nasty-looking stuff!

 

[MarkMaxPayne]

Bish's Service Center in Junction City, OR replaced my toilet switch yesterday on my 2023 Newmar New Aire with the one I mentioned in my previous post. With the replacement switch my toilet now sends water into the bowl while flushing just as it was designed to before covid supply chain issues had Newmar swap to a different switch that only allowed you to add water or flush separately. Yay! Happy wife, happy life!

Best,
-Mark