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pianotuna
Hi all,

This morning my water pump worked fine for me. When it is switched on there is a light that illuminates.

I normally leave the pump off.

Later this morning my wife tried to use the pump.

The light did not illuminate and the pump did not pump.

I tried switching fuses but this seemed to have no effect--although I did note that there was a small "spark" when I put the different fuse in place, and also when I returned the fuses to their original locations.

Any advice on trouble shooting would be appreciated!

Thanks in advance.
Denali
The first thing I would check is whether the pump is getting 12 VDC. If it is, you know the problem is either the pump or the pump's ground connection.

If it is not getting voltage, then I would read across the switch to see if it has continuity when it is in the "On" position. Of course, you want to remove the wires from the switch before reading continuity across it, so you don't smoke you meter.

I assume that you only have one switch that controls the pump. If not, there is a latching relay somewhere in the circuit that might have failed.
pianotuna
Hi Denali,

Yes, just one switch--but getting access to it will not be easy. I think I'll take the coward's way out and let the dealer fix it.

The problem is that it now gets well below freezing at nights, so I need to winterize the pump. Which I can't do if it won't function.

I've made a special effort to become "known" at the RV place, so if I explain the situation they may take me right in.
John Blue
Don,

Dave has the correct answer. Find the latching relay and see if it is moving. Each time you close the water pump switch his relay will open or close. The thing is hard to find and could be anyplace in MH. This relay will power up Red led as well. Sometime you can tap it a little and free it up.
pianotuna
Hi,

Thank you all for the suggestions!

Just an update.

The RV place had to replace the switch. It had died. I hope this will not be a regular occurrence as there are two other identical switches in the range hood/control panel.
Denali
QUOTE(John Blue @ Nov 15 2009, 05:28 PM) *

Don,

Dave has the correct answer. Find the latching relay and see if it is moving. Each time you close the water pump switch his relay will open or close. The thing is hard to find and could be anyplace in MH. This relay will power up Red led as well. Sometime you can tap it a little and free it up.
He later posted that he only has one switch for his water pump, so he doesn't have a latching relay.
John Blue
Dave,

We only have one switch at kitchen sink and have the latching relay. The switch is a spring action type. Each time you close switch the relay changes state from on to off. Most motorhomes have two switches but work the same way as each switch is wired to same input on relay. If the water pump switch were the locking type then you would not need the latching relay. Foretravel only uses the latching system as some motorhomes have one switch and other models have two switches.
Kirk
QUOTE(John Blue @ Nov 20 2009, 08:50 PM) *

Most motorhomes have two switches but work the same way as each switch is wired to same input on relay. If the water pump switch were the locking type then you would not need the latching relay.

I am wondering about this statement? I have seen very few RVs that used a latching relay for the water pump. In fact, I have been fulltime in our motorhome for ten years and while we do have two pump switches, if there is a relay I'm sure not aware of it, nor do I know of any reason why we would have one? As a retired electronic tech I think that I would recognize one if there were, but can't swear that it isn't there. I can tell you that I have two rocker switches of two position. Just like when you have any other two way switch arrangement, you can turn one on and the other off.

I just checked the switches and when both are in the same position, the pump (and it's red light) is off but when the two are aligned differently the pump & light are on. Just as in most two way switches, what I have is the 12V connected to the center pin of one switch and the pump to the center pin of the other switch. There are two wires between the two switches, both connected to the outside pins of the switch. I have not traced the wires, but I am pretty sure that there is no relay involved. All RV water pumps that I have worked on in the past have been this way if they have two switches.

Have I missed something?
pianotuna
Hi Kirk,

Yes, what you have missed is the "remote switch mentality" that tries to save ten cents on wire by putting a relay in so that a smaller wire size can be run--leaving the owner with a system that may someday fail and be miserable to fix--seeing as the wiring diagrams that come with an RV are "less than precise" about the location of such equipment.

My RV doesn't have a relay. Cost for fixing it was $27.95 for a new switch and labor.

Denali
QUOTE(John Blue @ Nov 20 2009, 07:50 PM) *

Dave,

We only have one switch at kitchen sink and have the latching relay. The switch is a spring action type. Each time you close switch the relay changes state from on to off. Most motorhomes have two switches but work the same way as each switch is wired to same input on relay. If the water pump switch were the locking type then you would not need the latching relay. Foretravel only uses the latching system as some motorhomes have one switch and other models have two switches.
Thanks for the information, John.

I was generalizing from what I have seen in Monaco coaches, which I obviously should not have.
John Blue
Kirk,

Don hit the nail on the head. Cost less to drop the relay.

Here is the plan. You have a small #22 awg gauge wire from rocker switch down to latching relay coil. On relay contacts you have a larger #12 awg from cir. brk. to latching relay. From this relay #12 wire down to water pump due to heavy amp pull on motor. This is mounted about six feet from water pump in a Foretravel and all power to cir. brk is a very large cable from batteries. As Don said this saves money but you will have a burn out at rocker switch at sometime due to heavy current flow as Don found out.

It cost less to go cheap but people at Foretravel never do this. You can add any number of switches you wish with this set up. Each switch will reset the relay state to on or off. We have never had a problem in our long years with the motorhome yet due to power problems of any type. Other units will be wired up in different ways to save a couple bucks.

Hope this will help.
gsbogart
QUOTE(John Blue @ Nov 22 2009, 02:52 PM) *

Kirk,

Don hit the nail on the head. Cost less to drop the relay.

Here is the plan. You have a small #22 awg gauge wire from rocker switch down to latching relay coil. On relay contacts you have a larger #12 awg from cir. brk. to latching relay. From this relay #12 wire down to water pump due to heavy amp pull on motor. This is mounted about six feet from water pump in a Foretravel and all power to cir. brk is a very large cable from batteries. As Don said this saves money but you will have a burn out at rocker switch at sometime due to heavy current flow as Don found out.

It cost less to go cheap but people at Foretravel never do this. You can add any number of switches you wish with this set up. Each switch will reset the relay state to on or off. We have never had a problem in our long years with the motorhome yet due to power problems of any type. Other units will be wired up in different ways to save a couple bucks.

Hope this will help.

The relay you are describing is a latching relay. The way it works is the relay is grounded through the rocker switch with a 12 negative wire from the relay to ground. When you shunt the relay to ground through the switch, the voltage on the wire from the relay will be approx 7.4 volts when the relay is latched, and 2.4 unlatched. Placing a test light across the switch terminals will tell you nothing.
As a side note....
If you want to put a LED light in the circuit at each switch you can do so by series wiring two LEDs together in the proper polarity and wiring them across the switch terminals. Or.... If you can find a LED that has a voltage range just above 2.5 volts, and 8 volts that would work, but I have not been successful in locating one. Radio Shack is my only source of LED's locally.
John Blue
gsbogart,

We have a Red LED at rocker switch so you can see if power is on or off to the pump motor. Works great.
gsbogart
QUOTE(John Blue @ Dec 18 2009, 03:39 PM) *

gsbogart,

We have a Red LED at rocker switch so you can see if power is on or off to the pump motor. Works great.



That is great that your indicator light works. My post was if you want to expand the switches and or indicator light at each switch. One in the washup bay, one at the toilet area, or one near the kitchen sink, anyplace you would want an indicator light or switch but don't have one. and....how the relay functions voltage wise.

Not having a latching relay has no bearing on whether you have a single switch or not. It is a matter of the amperage load that is placed on the switch from the pump motor. They run anywhere from 10 to 25 amps. This kind of a load would soon destroy a light weight load switch. A regular relay could be used, but the problem is motorhome circuits are designed to go easy on battery draining loads to conserve battery hours. A regular relay would have currant running through the coil all the while the relay was energized. A latching relay does not require that. It is only drawing currant during the initial latching or unlatching phase.
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