BAC Forum
General Boards => Technical Support => Topic started by: Fred Brooks on November 25, 2025, 08:34:28 PM
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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!