Water Pump relays, switches, and wiring 99-2001 Marquis

[Fred Brooks]

    Greetings fellow Beaver folks,
 It has come to my attention that there is a lot of confusion how the domestic water pump on 98 to 2001 Marquis coaches is wired and controlled from multiple locations. Beaver was one of the first manufacturers to engineer a multiplex control system to turn on the house water pump from 4 different locations. Unfortunately, there are no electrical prints available to troubleshoot the system when there is a failure. I have reversed engineered the system and created a schematic to help folks understand how Beaver built it. The 2 relays that control the water pump are mounted in the upper part of the enclosed water pump and tank fill plumbing box and identified. The wiring from all the switches and lighted indicators are all daisy-chained together. I was going to add this to our technical library, but it seems to be difficult presently. Hope this helps so the original engineering can be preserved. Blessings & Joy to all this Thanksgiving!

[David Ciotti]

We arrived at Asheville this week just in time for a cold snap.  The management at Campfire Lodgings request we disconnect our RV from the water system for freezing nights.  So while I was filling my Fresh Water tank we decided to go out for Pizza.  When we returned there was water gushing out of the bottom of our Marquis.  I could not find the source of the water and nothing in the RV was wet but I remembered I left the Fill switch on and turned it off.  It did not fix the leak.  Shutting the city water valve off did not fix the leak.  I could not find a way to fix the leak.  The water level in the fresh water tank was dropping, dropping, dropping.  My wife went to the store to buy bottled water.  While she was gone the leak fixed itself but the fresh water tank was empty.

I turned the city water back on, no leaks, and the water system operated normally.  So I turned the fill switch back on and the fresh water tank filled normally.  I shut off the switch at 50% full.  Everything has been operating normally.

What I think happened is there must be an overflow tube connected to the bottom of the fresh water tank and it is routed over the top of the tank and it siphoned the water out of the fresh water tank until the tank was empty.  Once empty the siphon cleared and the leak stopped.  Now everything is back to normal.  That is if you consider 19 degrees in November if North Carolina normal.

[Fred Brooks]

  Greetings David,
  I am not too sure if Monaco changed the engineering on the '02 Marquis. It sounds like one of two scenarios may have occurred. The original Marquis procedure was to be connected to city water. 2- push the tank fill switch and when the tank monitor senses it has reached the "full" probe in the tank, it automatically shuts off the fill solenoid (red hat valve) and returns to the city water pressure. If that red hat valve never shut off, city water would continue to fill and finally overflow thru the vent. That could occur if the full probe is corroded or disconnected or the red hat valve failed in the open position. The other choice would be someone left the tank drain valve open by accident. Hope this helps, Fred

[Carl Boger]

David I absolutely consider 19 degrees in Asheville normal in November!  I used to own a cabin in Zionville outside of Boone and I have seen -5 degrees in November up there.

As for your siphoning theory I am in agreement with you.  My coach has a manual switch, but if I don't turn it back to city water instead of fresh water fill it will continue to pull water out of the overflow.  I have never left it open long enough to see how much water would drain, but it will drain some.

[Fred Brooks]

  I am not real sure where the vent is located on top of the tank. It may siphon off a little depending which way the coach may be leaning, however the "full" probe allows for air space above the water level and the top of the tank. I used a flow meter on my coach when filling my freshwater tank out of curiosity and it shut off at 91 gallons. Beaver stated that the capacity was 100 gallons. I still think his issue is the Red-hat solenoid valve or the tank probe not responding. Fred

[Eric Drickersen]

Thank you Fred! Your guidance has been super helpful in getting my marquis functional. I am using your schematic to trouble shoot my water system. As I had previously mentioned, the confusing part is that I there is a loss of 12v current somewhere between the breaker (located in the closet) and the relays. I am also getting a 10v reading on the ground bus. Based on our conversations, I have decided to start with replacing the two relays while also tracking down the cable run between the breaker and relays.