Water pump problems

[dspaw]

This relates to the 12V water pump for the coach water system.

The pump is not working. In the 350, there are two switches that can activate the pump - one in the bathroom and one on the panel in the galley above the stove. The galley switch is receiving power and appears to be working properly even though the led associated with the switch does not illuminate. I have not taken the bathroom switch apart, but believe (based upon comments from the PO, wxbouy) that it is working properly.
The pump will run if powered (I have powered it with a power probe). Based upon these observations, I believe that the pump is not getting power when the switch is actuated, and think that there is a loose connection somewhere between the switches and the pump.

Unfortunately, I have no idea how this is wired or where the wires are routed. Any ideas?

Dave

[dspaw]

Ok. I have done some further testing and confirm that there is power at both switches and that both switches are operating correctly. I am about 70% sure I have an open circuit.
I am guessing that the wiring between the control panel switch is connected to the wiring from the bathroom switch somewhere between the bathroom and the pump, on the drivers- side aft of the bathroom.
Does anyone have any experience in this wiring, i.e., where the connection might be located? Any help or suggestions will be appreciated.

Dave

[bkahler]

Dave, have you verified that there is no voltage at the pump when you turn one of the pump sitches on?

Brad

[dspaw]

Hi Brad:

Yes - there is no voltage at the pump when the switches are pushed. The switches are working correctly - that has been confirmed. I think that somewhere between the switches and the pump there is an open circuit. I don't have a lot of (i.e., any) experience with tracing wires in the moho, and don't know where the wires go or how to get at them. Are they normally buried in the walls? I would like to limit the carnage as much as possible.

Dave

[mayco]

I know you verified that the pump works from your previous post. My next step would be to make absolutely sure which side of your power supply is causing the problem....positive or ground. Its easy to make assumptions that its one or the other but not with these Classic Motorhomes. There isnt any logical reason I can think of that there would be a joint in between your switch and the pump on the positive side. If indeed you are absolutely sure that you have 12v power leaving your switch, I would turn on the switch and test the positive side at the pump using an independent known good ground. Then I would do the same thing on your ground side. From what youve posted, you essentially have the equivalent of 2 three way switches with the same type function as those in your home. I dont know how 3 ways are wired on DC current. My guess is that the problem isnt behind the wall somewhere, just a guess but I cant think of any reason you would have a joint of any sort between the switch and the pump. Fairly improbable that the 12ga wire has been cut in two. If those 3 ways are wired similar to AC switches then there are two options for the current flow..... switch to pump to switch....or...switch to switch to pump.

[bkahler]

Dave,

I'm pretty sure the fuse for the water pump circuit is before the switches so the fact you have power at the switches indicates the fuse is ok. If your DC fuse panel is in the cabinets below the status panel where one of the pump switches is then the most likely path to get to the pump would route the wires from the fuse panel up to the status panel, over to the switch in the bathroom and then on to the pump. Which means the wires would be going up the wall from where the fuse panel is, up the wall and to the status panel and then across the ceiling and down to the bathroom where the other switch is. From there the wires most likely go back up into the ceiling and head back until they reach the area of the pump and then would be routed down the wall to floor level where the pump is.

The wires are somewhat color coded so if you can identify which wire would be the feed to the pump that should help track it. Of course all of the above is on the assumption there is only one 12volt feed wire at the pump.

Brad

[Vycan]

BLUF: With your water pump on, Check the negative crimp from your motor on both sides of the splice and the positive going into the pump. If you have 12V, it's the motor.

I had a similar issue with my generator. Similar that the generator has two remote switches for activation, and while I could turn it off, I could not turn it on from the switches, and would need to turn it on at the generator itself. I tested the switches, and they showed 12v from switch to a known good ground. I then tested for continuity and had continuity at all the correct poles with the correct positions, but still no remote start on the generator. Thinking it was the control board for the generator I picked up a new one. The old one was on an open circuit board and had signs of weathering and corrosion. Wanting to replace this with a sealed board anyway I purchased a new one hoping it would work. No luck. So I pondered it some more, and one day while tinkering on the coach I was thinking what a Frankenstein our coaches are, and that nothing is custom made for them due to the low volume, so I should check the harness. I pulled the harness apart and everything looked fine. I had my daughter help me by holding the switch so I could test voltage at the harness' pin. zero volts. Eureka! The harness is spliced in place with stereo splices, so I stuck a probe inside the splice 0V. Eureka. I pierced the wire an inch from the connector since this part of the harness, while wrapped, is subjected to a lot of moisture if driving in inclement weather, and read 12V. Eureka! I gave the harness a good pull and the line popped right out, but it was an electric line flush with the insulation, covered in corrosion. I pressed the probe gentle against it... zero volts! I pressed harder through the corrosion... 12v! The crimp on the splice was done with too little insulation stripped, and the insulation was caught in it, so it had a loose connection, and a way for water to pool since it would rest vertically, and the additional void space in the connector acted as a tiny cup to hold a drop of water. I re-crimped it, and fired the generator right up at both panels. So the point of all this.... know your connections and splice locations.

[dspaw]

Thank you for all your comments. I will do some further investigating and report back.

Dave

[Al and Missy]

The water pump switches are just like 3-way switches in your house. In my trailer, the water pump is on the curb side, along with the control panel in the stove vent. 12V power is supplied from the fuse panel to the bathroom switch. The two wires (orange) from the switch go to the switch in the control panel. The wire from the switch in the control panel goes to the pump which has its own ground. There are several wiring harnesses involved, with connectors between them. I doubt that your MH is wired like my trailer, so I can't help you with their locations.

You said you have power at the switches. One of the switches should have power on the center lead at all times, and the power should move between the other two leads when the switch is thrown. At the other switch you should see the power moving between the two leads. Then you should see power at the center lead of that switch when it is placed in the right position. If all of this is correct, then the problem is with the wire from the center of the switch to the pump. IF all else fails, run another wire.

[dspaw]

Good news - crisis averted.

I want to thank everyone for their help. Turns out the circuit is wired from the fuse to the control panel to the switch in the bathroom to the pump (thanks Mayco). The switch was wired wrong (there are several not connected wires in the wall behind the switch). After I realized that, and found the correct wires in the wall, it was a pretty simple matter to connect the correct wires to the switch. The pump operates correctly now!!

Question: I want to label wires as I go through the moho. What is the preferred labeling method? Is there something that is made especially for labeling wires? Pen on masking tape does not seem to be durable.

[rmkrum]

Suggest one of the Brother P-Touch label machines. The tape is self-laminating and seems to be fairly durable out of the sun

Can be found at most big box hardware stores, warehouse clubs, and online. Fairly cheap. I got one from Costco with extra tapes for about $30.


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[dspaw]

Rkrum:

Thanks for the suggestion.

Dave

[mayco]

Good job Dave!!!!! Ahhhhhhh what a good feeling to sort out an electrical problem on these beauties. In m opinion, and others I think, the electrical wiring is perhaps the weakest link on our rigs. (have you looked at Bob's new 370 wiring project? Oh my) one thing Ive learned that works for me is to attack an electrical problem addressing the simplest things first. Fuses, connections, grounding, etc etc... I try NOT to assume ANYTHING in regards to the electrical workings on my rig. Though you may eventually run into a problem that requires opening up a wall, most of the time Ive found the problem in an accessable spot ie. Switch, dirty ground, PO mistakes or mods, etc.....

Good job with your detective work!

Mike