We have a bizarre problem! When I turn on a switch for a 12 volt light, sometimes it works. Other times instead of turning on the light it is turning on the vent fan which that switch does not control at all. Sometimes when I turn on a 12 volt light switch, all the 12 volt lights and the 12 volt vent fans go off as well as the refrigerator which beeps. This only started tonight and has never happened before. The camper worked fine at home. Now that we're at a campground and plugged into a 50 amp box, it started happening. We used the same box a year ago and it worked fine. Any suggestions as to why our 12 volt light switches are controlling things that are not even connected to them? And why that is causing the refrigerator to go off and on? Thanks so much for your help!
12 Volt lights/fans go off and on
- Thread starter djreg
- Start date
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Related to this issue is the fact that as we were setting up we could not lower the electric jacks while the slide outs were moving out. Didn't think about it at the time, but apparently there was not enough 12 volt power to make it work. I also noticed that in trying to turn on 12 volt lights or fans, it would sometimes make all of the 12 volt things go completely off. The lights aren't dimming like they do when there is low power - they just turn off. Any idea as to why this is happening?
Thanks so much!
Thanks so much!
Removing the cables from your battery and cleaning them before replacing (and tightening) them may help. If there are any smaller wires attached to either battery post, make sure you put those back as they were. Also check/tighten the negative battery cable end where it attaches to the frame.
Alfa38User
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- Oct 4, 2007
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Very marginal house batteries perhaps?? Using a voltmeter, measure the voltage across the battery terminals while not plugged in or running the generator. Then plug in and do the same thing again. This will prove that the converter is at least able to charge the batteries
I would not think that you should be moving both the slides and the jacks at the same time as you would likely be demanding way too much from your 12V system. Depending on the coach, some require that the jacks be down and the coach level before extending the slides, others just the opposite. I have never heard of doing both at the same time, especially if they are both 12V operated.
If the battery condition is poor, turning on one thing too much can cause a drop severe enough to make the lights appear to go out. (They may have a "glow" if examined closely but appear to be off from a distance and through their covers.) A dirty connection, especially the ground side at the chassis end, can also cause similar symptoms.
I would not think that you should be moving both the slides and the jacks at the same time as you would likely be demanding way too much from your 12V system. Depending on the coach, some require that the jacks be down and the coach level before extending the slides, others just the opposite. I have never heard of doing both at the same time, especially if they are both 12V operated.
If the battery condition is poor, turning on one thing too much can cause a drop severe enough to make the lights appear to go out. (They may have a "glow" if examined closely but appear to be off from a distance and through their covers.) A dirty connection, especially the ground side at the chassis end, can also cause similar symptoms.
Gary RV_Wizard
Site Team
I think you have a short in the wiring somewhere, making intermittent and oddball connections. I don't see how low voltage, battery or converter, could cause all those weird things.
Please tell us what year/make/model of RV this is, so that we have some idea about the electrical system configuration.
Please tell us what year/make/model of RV this is, so that we have some idea about the electrical system configuration.
Alfa38User
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- Oct 4, 2007
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djreg said:
Oopps, I ass-u-med coach, not a fifth wheel from your description of operating jacks and slides at the same time, my bad...
Is there only one?? Is "it" being charged while underway?? You are definitely 12V under-powered despite having a fairly new battery and you may be overloading your 12V system. It bears looking into for both charging while underway and charging while plugged in though, to be sure you have a battery that is fully charged before attempting any 12V electrical operations. Were you plugged in to a 120V power source while this was happening or just running on battery?
By "jacks", I now assume you mean the stabilizer jacks, not the main one used to remove the trailer from the truck and level it fore and aft. Stabilizer jacks are not meant to 'level' the trailer but only steady it a bit more once level IE very little downward pressure is required. They are usually smaller motors and do not draw a lot of current but... To level side to side, if necessary, drive up on planks under the low side wheels.
Personally, I can't subscribe to the "shorts" theory without ruling out the simple stuff first.
We have disconnected the battery and still have the problem. We have checked and tightened all of the ground wires from the converter. I have repeatedly turned on every 12 volt light/vent fine in the camper and they work fine until.........................I start turning them off one by one. Just as I flip the switch off on about half of them, everything goes off! I've experimented with only turning on the vent fans, only turning part of the lights, and have found that running all 4 vent fans, then turning them off does not crash the 12 volt. However, a combination of fans and lights, or just lights (more than half turned on) will crash as I turn off the switch about half way through.
Gary RV_Wizard
Site Team
How good or comfortable are you with diagnosing 12v electrical circuits? This is very likely a trivial problem but one that will be hard to isolate and find. It is going to require use of VOM (voltmeter and ohmmeter) and a lot of disciplined & careful testing of individual circuits to rule out potential problems until only the real problem is left. Skipping around isn't going to find it, nor will haphazardly replacing things.
One thing I would do while I was trying to think of something to do that actually made sense, 
is to check each 12V lamp socket and ensure that the correct bulb is installed. (i.e. no single element bulbs in a socked designed for double element bulbs.) Just a thought.
is to check each 12V lamp socket and ensure that the correct bulb is installed. (i.e. no single element bulbs in a socked designed for double element bulbs.) Just a thought.Maybe you have a bad ground (negative side) somewhere and things are back feeding through each other. Lights don't much care about polarity unless they are diodes but the fans probably do. See if the fans are all blowing in the correct direction. Fault probably is in a switch somewhere.
I know it is frustrating but can you identify a more specific pattern? It's odd that simply one by one--as in any light or fan in any order--would cause this. Can you isolate which ones are causing it? Are the lights turned on via a wall switch or on the fixture itself? What about the vent fans?djreg said:
Your first post mentioned, "Other times instead of turning on the light it is turning on the vent fan which that switch does not control at all." Was the vent on a wall switch or on the vent itself? Either way was it possible it was switched to the on position, but not actually on (as in fan blade turning or turning in reverse).
Also, no 12v fuses have blown during all of this?
Michael
All lights and fans are on wall switches. The light bulbs are the same ones that have been in the camper since we bought it 4 years ago. Our camper dealer/repair person has been helping us via cell phone today, especially with checking electrical circuits. He believes that the problem is the converter, and that when the front electric jacks were lowered while the slideouts were being opened, it damaged the converter. It makes sense because at home everything was working fine. As soon as we arrived at the campground and had the incident with the jacks and slideouts drawing from the 12 volt at the same time, the bizarre behavior immediately began! The converter has been ordered and we are hopeful it will fix our problem. We have a wonderful dealer that we work with and know that if the converter is not the cause he will do what else needs to be done to get it fixed! Thank you SO MUCH for all of your input. We really appreciate it. I'll try and remember to post to let all of you know if the new converter fixes it!
Gary RV_Wizard
Site Team
I'm rather skeptical of the converter damage idea. If it was damaged, it would probably just quit working. There aren't many (any?) things to go wrong with it that make switches work funny. I suppose it could be putting alternating current on the 12v wires, but even that isn't likely to have the results you are getting unless you have a digital switching system (switches trigger a circuit board which does the actual switching). I doubt if your RV has one of those, though. Well, I guess you will know when it gets installed.
You can test the 12dc wires for alternating current by using an AC voltmeter on the plus & minus wires. If you get an AC voltage reading above about 1.0v, you are probably getting AC in addition to DC on those wires.
You can test the 12dc wires for alternating current by using an AC voltmeter on the plus & minus wires. If you get an AC voltage reading above about 1.0v, you are probably getting AC in addition to DC on those wires.
I would also find it strange if it was the converter.
As far as I know the converter just supplies DC to the 12v fuse box via one connection and doesn't even know what circuits that fuse box feeds. Seems to me like you have a ground or other wiring issue. But maybe it is the converter doing strange things to the 12v supply. Stranger things have happened.
Mike
As far as I know the converter just supplies DC to the 12v fuse box via one connection and doesn't even know what circuits that fuse box feeds. Seems to me like you have a ground or other wiring issue. But maybe it is the converter doing strange things to the 12v supply. Stranger things have happened.
Mike
Kevin Means
Site Team
Unless I'm overlooking something, the only thing those systems have in common is the 12 volt bus. To me, the problems you described seem like classic symptoms of a short circuit in the 12 volt system. In our coach, some of our light switches and vent power switches are right next to each other. If yours are the same, I think I'd start tracing their wires with a VOM to see if one has come loose, and is intermittently touching a wire terminal on an adjacent switch. If your fridge's 12 volt power is on the same bus, the beeping might be an indication that the control board is turning on and off due to a short. Breakers and fuses don't always pop immediately.
Kev
Kev
Gary RV_Wizard
Site Team
Hey, that's great! Wish there was a better explanation of what was wrong with the old one. Sometimes the act of replacing a component is what actually fixes the problem.
