Help/ suddenly no 12v

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Lordismyshepherd

Lordismyshepherd

Well-known member
Joined
Jul 26, 2017
Posts
57
Location
New Hampshire
We are currently in an RV park in Trenton Maine. We have a 2001 Monaco Signature 45. Last night we lost our 12v. I had a kitchen fan on and turned on some lights and suddenly everything went dark. We still have 120 so I am at a complete loss. I am not able to locate a fuse or a relay that would control this, which doesn't mean it doesn't exist, I just can't find it if it does. I searched this site last night and saw that the most frequent causation of this has something to do with the "salesmen" switch and or its associated solenoids. It appears that jumping these has solved this problem for some. Since it was getting dark, and the fact that, I am also not the least bit mechanically inclined when it come to electrical systems I tried turning the switch from front to rear and back but no luck. I even tried disconnecting the power altogether in hopes that if it were a solenoid it would open up again, no luck. I am very skeptical to mess with anything electrical for fear of making a bad situation even worse. We're supposed to be here for the next 9 days, (and of course today is my wife's birthday, not the celebration I had planned) so I am hoping someone might be able to point me in the rights direction, or, can recommend a mobile/fixed repair service.
Thank-you in advance
Art
 
Well there is a suspect list but I'd need to know more about your electrical system to narrow it down
First you have a converter. This is fed by 120 volts (Via a circuit breaker normally) If that trips your batteries run down.... It has fuses Either on the converter or as part of the fuse panel (If the converter is built into the panel) if they are blown the batteries run down...
Now moving toward the battereies there are more fuses or another circuit breaker. This breaker (if that's the option) may be different from what you are used to.. Finally the batteries themselves.
Testing procedure.. I suggest a test light because once you know it's working it has basically 3 states BRIGHT (Good) Dim (not good) Dark (also not good) And you thus do not need to "Read a meter" which can cause you to shift your eyes to somewhere other than where the probe is touching with bad results (Probe moves and shorts somethign)
Start wiith your car battery Should be bright (Testing lamp to insure it works)
Now on to the house batteries.. If DIM/Dark try a stand alone automotive charger to bring 'em up.
Now move the clip to body/rame part and check for BRIGHT at last known good point.. Move tip out along positive lead.. Every terminal (both ends of anywire) test.. Bright is still good. Problem exists between Bright and Dark.
 
Happy birthday to your wife. Hope she still has a good day.

Go to the park office and ssk them for a referral. Many campgrounds will have a bulletin board where venders leave there business cards.
 
"Everything went dark" as in *all* 12V equipment - water pump, refrigerator panel, AC/furnace thermostat, water heater control, level indicators, TV preamp, (on and on) or just the lights and the fan that were in use? Having just a single circuit pop is a lot different than the entire coach. You tested 120V so that's a start. There is not a single component I can think of that controls "everything", even the salesman switch passes DC from the converter to the house so my first pass at this is to go around and see what works and what doesn't, and that would steer me to what to check. At a minimum I would inspect the 12V fuses in your power center and you probably have a separate bank of DC circuit breakers in a compartment.

Mark B.
Albuquerque, NM
 
Mark_K5LXP said:
"Everything went dark" as in *all* 12V equipment - water pump, refrigerator panel, AC/furnace thermostat, water heater control, level indicators, TV preamp, (on and on) or just the lights and the fan that were in use? Having just a single circuit pop is a lot different than the entire coach. You tested 120V so that's a start. There is not a single component I can think of that controls "everything", even the salesman switch passes DC from the converter to the house so my first pass at this is to go around and see what works and what doesn't, and that would steer me to what to check. At a minimum I would inspect the 12V fuses in your power center and you probably have a separate bank of DC circuit breakers in a compartment.

Mark B.
Albuquerque, NM
Click to expand...
Hi Mark,
Thank-you for your reply. The fridge runs on the 120 so that's a good thing. Anything that is run on the 12 volt, interior lights, fans, toilet, thermostats, are no longer functional. I have tested all the fuses that power these and reset all of the breakers. My charging controller says that the house batteries are charged to 14 amps.....
 
Rene T said:
Happy birthday to your wife. Hope she still has a good day.

Go to the park office and ssk them for a referral. Many campgrounds will have a bulletin board where venders leave there business cards.
Click to expand...
Thank-you Rene! I did speak with them and they were able to refer me. I am going to give them a call. I was hoping to avoid needing them but I know my limits. I don't want to turn what might be a minor problem into a fire!!
 
A curious situation indeed. The "typical" problem is the converter fails and you unknowingly run on battery until they die. But when that happens it's not "suddenly", things dim first. Whether your batteries are any good or not, your measurement of "14 amps" (volts) shows your converter is working. The way mine is wired the house gets converter power irrespective of the salesman switch and if my salesman switch is off, the batteries wouldn't be seeing converter power. So by inference your salesman switch is on because your batteries are getting charge voltage. Looking at the diagram for mine the only path for both battery and converter power to house is the distribution in the DC breaker box in the compartment next to my steps. It's a long skinny box with 8 or so white buttons on it, marked with a number: 20, 30, 40, etc. Make sure none of them are popped out, they should be nearly flush with the panel. Give each one a poke for good measure. If none are popped there are some thumbscrews that hold the panel in place and the innards easily accessed. I would start there with a voltmeter to see where DC is, and isn't. If it isn't one if these primary breakers tripped you're down to very few possibilities from between there and where your converter and batteries source house power.

Mark B.
Albuquerque, NM
 
Lordismyshepherd said:
The fridge runs on the 120 so that's a good thing. Anything that is run on the 12 volt, interior lights, fans, toilet, thermostats, are no longer functional.
Click to expand...
Are you sure that the refrigerator is running? If you have a typical RV absorption refrigerator it requires 12V power to operate even if on 120V. If it is the RV type, check to see if there are indications on the control panel or the interior light turns on when the door is opened. If you have lost all 12V an RV refrigerator will not work.

If you have a house type refrigerator that only operates on 120V then it should be working
 
Mark_K5LXP said:
There is not a single component I can think of that controls "everything", even the salesman switch passes DC from the converter to the house
Click to expand...
Not in every RV electrical system, Mark. My last coach (2004 American Tradition) had a "mains power" disconnect that removed both house battery and converter/charger 12v from the entire house. Everything! There were also two 50A DC breakers in the Battery Control Center that disabled about 90% of the common 12v stuff by shutting down two major buss bars that handled lighting and some of the appliances. And I can think of at least two major fuses in the 12v system that would shut down most DC functions.
 
As Kirk noted, if you have an RV fridge and it's working on 120v, then you have at least one 12v circuit working. That would be an important clue, because "almost all" not working is much different than no 12v at all.
 
Check your batteries and their terminals. Check the ground connection to the frame (or wherever it goes). Grab hold of them and and try to turn them in the posts.
 
Lordismyshepherd said:
We are currently in an RV park in Trenton Maine. We have a 2001 Monaco Signature 45. Last night we lost our 12v. I had a kitchen fan on and turned on some lights and suddenly everything went dark.
Art
Click to expand...
I had a similar thing happen when I was boondocked at French Camp, near Tom's Place, CA (the camp @Old_Crow runs) just before a very cold night, last May. It happened just after I was running the genny. I had no 12 Volts unless the genny was running. This was in my Y2K Class C RV (listed below).

I never did figure it out as it appeared the open had to be in a large cable that ran underneath the RV. Converter to battery box was totally open. And all the DC stuff was on the converter side of the open.

I never bothered to mention it here, as it looked more like a mechanical issue to find the fix--that probably would not be possible to repair and find the actual problem anyway.

I made an emergency repair for that night which I made as a permanent modification later. For that night, I ran clip-leads from the house battery to the output of the converter so the refrigerator and furnace fan and lights would all still work. Never did figure it out and the next day I took a 10 gauge AC cord apart to get wire from it to make this repair permanent. How the cable under the 22 year old RV became open that runs under the RV--or whatever it was that caused it, I never did bother to figure out. But whatever it is, it has to be a cable or whatever else is on top of the crossover that runs under the RV. Seems almost impossible to work on in that area, so I will just leave it as is, as everything works with my simple modification.

-Don- Auburn, CA
 
Last edited:
Gary RV_Wizard said:
As Kirk noted, if you have an RV fridge and it's working on 120v, then you have at least one 12v circuit working. That would be an important clue, because "almost all" not working is much different than no 12v at all.
Click to expand...
Thank-you Gary,
Thankfully the fridge is running, and thankfully it's been very comfortable here so not having the a/c isn't an issue. I inquired from several people in the area about a mobile rv service and they all recommended the same one. I have contacted him and he will be tomorrow (Monday). I'll post the problem and resolution just in case anyone should have a similar issue in the future.
 
I wanted to first, thank everyone who offered their advice in order to help us resolve our problem. It's comforting knowing that this wealth of knowledge is available. I contacted 207 RV Service based on several recommendations. Dan provided a quick response, within one hour after my original call on Saturday, was able to schedule us for today(Monday), I was fearing the dreaded, we're booked for the next two weeks. He arrived when scheduled, quickly diagnosed and resolved the problem which turned out to be the solenoid for the dash mounted battery cut-off switch. Dan was very professional and knowledgeable. I hope you never have the need for an emergency mobile technician but, if you do, and you are in Maine, 207 RV Repair is the first call you should make.
 
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