BAC Forum
General Boards => Technical Support => Topic started by: Rick Daniels on December 17, 2022, 04:26:05 PM
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strange issue this morning. All of the sudden none of the water pump on/off switches will turn the water pump on unless you hold any one of the switches on. If I press and hold the switch the pump stays on until I release the switch and the pump shuts off. Clearly the pump is working but I cant run water unless I press and hold any one of the switches. When I let go, the pump shuts off. I cant connect to city water due to sub freezing temps so I have to rely on the pump to draw water from the fresh water tank. Advice would be appreciated.
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Look for a pump controller like this: it may be close to the water pump. Replace the controller and you should be good to go.
https://intellitec.com/water-pump-control/
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Thanks Bill Lampkin, however an earlier post on the forum by Fred Brooks indicated that that device was not used until Monaco took over. I have never seen one of those in my coach. Until I find a fix I have to find someone to hold the switch while I shower or go without which is not an attractive option.
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Rick,
The SMC era coaches had their own version of a multiplex controller. Inside the water pump & plumbing box, you will find the 12 volt "hold relay". I cannot tell you which one it is because I have not seen one fail. A test light should identify the respective relay. Merry Christmas!
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To find the relay, just trace the power wire on the pump back to the relay.
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Actually the 2 relays on the top of the box are the ones you are looking for. One is the trigger relay and the other is the hold relay. When you push the momentary switch upward, the trigger relay activates the "hold relay" which turns on the pump. When you push the momentary switch downward, the "hold" relay deactivates. Fred
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In the event one or both are bad how would I identify the part number or brand to search for a replacement? Any thoughts on a source?
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Those relays are standard automotive relays; NAPA or any parts store will have them.
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Interesting observation. I find only one relay near the water pump. Also there three wires not connected to anything that do not go to the water pump directly. Some, if not all go into the water bay. They have been there and have had no purpose since I have owned the coach. Anyone know what they might have been for?
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Rick, I have the same 3 wires not connected to anything. If all you have is a single relay, and the red wire from the pump is going to that relay, take a picture or two. Then remove the relay and note the amperage on the top and any Autoparts house will have it. Fred
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brand new matching relay, water pump will still not stay on without holding the switch.
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Rick, how many remote water pump switches do you have? Do you have the same response from each of the switches. If you do, you may have a ground issue. I will go to my coach tomorrow and see if I can duplicate the issue you are going thru. One final question, when you are filling your fresh water tank, does it stop filling automatically when the tank level states it is "full" ? Fred
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I have three switches in the coach; over the dining table, bath sink and lav. There was one in the water bay but that one has been out of the coach for a couple of years. And yes, the fill switch seems to shut off when tank is full. I say "seems" because I monitor it and when the indicator says full, I switch it off. Necessity is the mother of invention. I recalled my "Red/Green" methods and have engineered a emergency system that now allows me to shower and do dishes without having to call the neighbor over to hold the switch.
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Thanks Rick, Cool idea with the stick in the wall trick. I'll try and figure out a PCR (problem, cause, remedy) tomorrow. I am not sure if all the switches are daisy chained together and something has become disconnected or a lost ground wire. I'll try and draw up a schematic of the logic once I figure it out. Fred
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Rick, if there are two relays side by side, try replacing the other one. As Fred says, the second relay creates a 'latch' circuit that will run the pump once you let go of the switch.
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One would think the latching relays for the water pump and shore water valve (red hat valve) would be in close proximity. The kitchen switch for my shore water valve has been disabled in favor of having the only other switch operative in the water bay. I have no idea where the latching relay for the shower water valve is but I have not spent much time looking for it. Is it in the compartment along with the water pump's latching relay?
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On our coach, the shore water fill valve (red hat valve) is controlled via the aladdin tank level module. I had to jumper the wire connector at the module to allow the fill valve to work when the tank level module failed.
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Rick, enclosed are some pictures and the schematic of the "run relay" and the "latching relay". Here is the PCR to get you to the finish line. Problem: water pump will not stay on and run. Cause: diode has an open circuit or disconnected wire between terminal 86 or 87 on the "run relay". Repair: replace diode or repair continuity between terminals 86 & 87 on the run relay. Here is the relay logic: terminal 30 is 12volt supply to relay. 86 is 12volt to activate relay coil. 85 is the ground to complete coil circuit. 87 is connected to 30 when relay is Not activated. 87A is connected to 30 when the relay is energized.
I did not see 2 relays together in your picture but they must be somewhere close by. Fred
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Fred
That's a very nice schematic drawing are you sure you weren't a draftsman in a previous life .
The lettering is a dead giveaway. LOL
Eric
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Eric, Mechanical Engineering 1968 @El Camino College Torrance California. Thanks for the kind words & Merry Christmas!
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Very informative info Fred Brooks. In search of the second relay, using your diagram as a guide, I followed wires from the visible and recently replaced relay. It appears as though at least two of the wires from the known relay pass through a hole in the wall into the water bay itself, next to the grey tank. There I found can of worms of wires as if they were just shoved through the hole from the water pump side as reflected in the photo. This was obviously not professional or factory job. Amongst the can of worms of wires in the water bay I found a small flat object that at least one of the wires from the know relay goes into with wires coming out the same end. It does not resemble a relay at all. It is wrapped in electricians tape. Could this be something like a diode or relay. Access is blocked by water lines coming from the manifold which will make it impossible to get at without removing the entire manifold. To add insult to injury, we are expecting temperatures as much as-38 below zero starting tomorrow until Christmas. Then we get 40 degrees above. Is there anyway you might know of that I can bypass all the systems and rig the water pump to turn on and off independent of all relays and diodes and remote switches to get by for just a few days. Anyway have a Merry Christmas.
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You could bypass the relays by finding the black and red wire that go to the pump. Run the black wire to a good ground and run the red wire (with an inline 10a fuse) to 12v+. The pump has a pressure switch that will turn on the pump when any faucet is open.
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Thank you Bill Lampkin. I'm off to the parts house. Merry Christmas
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Rick,
It is starting to look like someone who did not understand what he was looking at got creative. Enclosed is a picture of the diode after I cut the FLAT heat shrink off that enclosed it. As you can see, it has the blue and red wires.
To perform a temporary repair, find the 2 red wires that are 12volt positive. (if you can't find them, find 1 red that is 12volt positive. Connect it to the water pump red wire with a wire nut. Find a white ground wire and connect it to the water pump black wire. The pump should now run when a faucet is opened. Please keep in mind this is Temporary!!! Fred
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Will the fill switch for city water to fill my tank still work? I cant stay hooked to city water other than to fill as the hose freezes and the supply is to far away for a heated hose.
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Rick,
I would give it a try and see if it works. Did it work before?
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Yes the fill switch did work before. I think I will wait to continue this challenge until after Christmas. There will be a 75 degree temperature increase between wednesday night and Christmas day. Thank you Fred and Bill for all your help.
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reliable water flow via onboard water pump is still elusive. sometimes it works sometimes not. In trouble shooting the issue I determined that when an attempt to turn on the water pump works, an adjacent mounted solenoid clicks simultaneously with the pump turning on. If that solenoid does not click the pump does not turn on. Result no running water. Does anyone know what function that solenoid plays and is it possible my problem is a bad solenoid. Photo attached.
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Rick, someone has added the solenoid to replace the original engineering. Conventional wiring of an 80 amp solenoid is as follows: The 9:00 post is 12volt power in. The 3:00 post is 12volt power out. The little post (red wire)? is the trigger post that activates the solenoid so long as it has continuous 12volt power. The other little post is the ground connection. Fred
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Kinda overkill for a water pump; If my memory serves, the water pump only draws 7 amps. Jumper the 9:00 post to the 3: post, the pump then should operate from its own pressure switch (if you have bypassed the relays as I previously suggested).
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Thanks to Fred Brooks and Bill Lampkin Problem solved (at least for now). What a wonderful resource the BAC Forum is. Thank You Thank You
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Glad you worked it out. You could replace the big solenoid and the two relays with the Intellitec controller I mentioned previously. Might make things simpler. Your exiting wiring should work ok (no need to rewire switches!).